diff --git a/src/DPD-REACT/fix_eos_table.cpp b/src/DPD-REACT/fix_eos_table.cpp
index c9c23b51f8..61b4e7501a 100644
--- a/src/DPD-REACT/fix_eos_table.cpp
+++ b/src/DPD-REACT/fix_eos_table.cpp
@@ -207,7 +207,7 @@ void FixEOStable::read_table(Table *tb, Table *tb2, char *file, char *keyword)
 
   // loop until section found with matching keyword
 
-  while (1) {
+  while (true) {
     if (fgets(line,MAXLINE,fp) == nullptr)
       error->one(FLERR,"Did not find keyword in table file");
     if (strspn(line," \t\n\r") == strlen(line)) continue;    // blank line
diff --git a/src/DPD-REACT/fix_eos_table_rx.cpp b/src/DPD-REACT/fix_eos_table_rx.cpp
index b39e029c3e..5e950642d3 100644
--- a/src/DPD-REACT/fix_eos_table_rx.cpp
+++ b/src/DPD-REACT/fix_eos_table_rx.cpp
@@ -321,7 +321,7 @@ void FixEOStableRX::read_file(char *file)
   char line[MAXLINE],*ptr;
   int eof = 0;
 
-  while (1) {
+  while (true) {
     if (comm->me == 0) {
       ptr = fgets(line,MAXLINE,fp);
       if (ptr == nullptr) {
@@ -427,7 +427,7 @@ void FixEOStableRX::read_table(Table *tb, Table *tb2, char *file, char *keyword)
 
   // loop until section found with matching keyword
 
-  while (1) {
+  while (true) {
     if (fgets(line,MAXLINE,fp) == nullptr)
       error->one(FLERR,"Did not find keyword in table file");
     if (strspn(line," \t\n\r") == strlen(line)) continue;    // blank line
diff --git a/src/DPD-REACT/fix_rx.cpp b/src/DPD-REACT/fix_rx.cpp
index f21914e2d5..165a3a6dbf 100644
--- a/src/DPD-REACT/fix_rx.cpp
+++ b/src/DPD-REACT/fix_rx.cpp
@@ -255,7 +255,7 @@ void FixRX::post_constructor()
   int eof = 0;
   char * word;
 
-  while (1) {
+  while (true) {
     if (comm->me == 0) {
       ptr = fgets(line,MAXLINE,fp);
       if (ptr == nullptr) {
@@ -804,7 +804,7 @@ void FixRX::read_file(char *file)
   char line[MAXLINE],*ptr;
   int eof = 0;
 
-  while (1) {
+  while (true) {
     if (comm->me == 0) {
       ptr = fgets(line,MAXLINE,fp);
       if (ptr == nullptr) {
@@ -858,7 +858,7 @@ void FixRX::read_file(char *file)
 
   nreactions=0;
   sign = -1.0;
-  while (1) {
+  while (true) {
     if (comm->me == 0) {
       ptr = fgets(line,MAXLINE,fp);
       if (ptr == nullptr) {
@@ -1155,7 +1155,7 @@ int FixRX::rkf45_h0 (const int neq, const double t, const double /*t_stop*/,
    // compute ydot at t=t0
    rhs (t, y, ydot, v_params);
 
-   while (1)
+   while (true)
    {
       // Estimate y'' with finite-difference ...
 
@@ -1254,7 +1254,7 @@ void FixRX::odeDiagnostics()
   double max_per_proc[numCounters];
   double min_per_proc[numCounters];
 
-  if (1)
+  if (true)
   {
      static bool firstStep = true;
 
@@ -1285,7 +1285,7 @@ void FixRX::odeDiagnostics()
 
      printf("me= %d nst= %g nfc= %g time= %g nlocal= %g lmpnst= %g weight_idx= %d 1st= %d aveNeigh= %g\n", comm->me, this->diagnosticCounter[0], this->diagnosticCounter[1], this->diagnosticCounter[2], this->diagnosticCounter[3], this->diagnosticCounter[4], rx_weight_index, firstStep, averageNumNeighbors);
 
-     if (rx_weight_index != -1 && !firstStep && 0)
+     if (rx_weight_index != -1 && !firstStep && false)
      {
         double *rx_weight = atom->dvector[rx_weight_index];
 
diff --git a/src/DPD-REACT/pair_exp6_rx.cpp b/src/DPD-REACT/pair_exp6_rx.cpp
index b0b9f97ca2..313e9f2583 100644
--- a/src/DPD-REACT/pair_exp6_rx.cpp
+++ b/src/DPD-REACT/pair_exp6_rx.cpp
@@ -731,7 +731,7 @@ void PairExp6rx::read_file(char *file)
   char line[MAXLINE],*ptr;
   int eof = 0;
 
-  while (1) {
+  while (true) {
     if (comm->me == 0) {
       ptr = fgets(line,MAXLINE,fp);
       if (ptr == nullptr) {
@@ -838,7 +838,7 @@ void PairExp6rx::read_file2(char *file)
   char line[MAXLINE],*ptr;
   int eof = 0;
 
-  while (1) {
+  while (true) {
     if (comm->me == 0) {
       ptr = fgets(line,MAXLINE,fp);
       if (ptr == nullptr) {
diff --git a/src/DPD-REACT/pair_multi_lucy.cpp b/src/DPD-REACT/pair_multi_lucy.cpp
index 9f5e494991..4aaea3f81b 100644
--- a/src/DPD-REACT/pair_multi_lucy.cpp
+++ b/src/DPD-REACT/pair_multi_lucy.cpp
@@ -356,7 +356,7 @@ void PairMultiLucy::read_table(Table *tb, char *file, char *keyword)
 
   // loop until section found with matching keyword
 
-  while (1) {
+  while (true) {
     if (fgets(line,MAXLINE,fp) == nullptr)
       error->one(FLERR,"Did not find keyword in table file");
     if (strspn(line," \t\n\r") == strlen(line)) continue;  // blank line
diff --git a/src/DPD-REACT/pair_multi_lucy_rx.cpp b/src/DPD-REACT/pair_multi_lucy_rx.cpp
index c386abded4..eac047d9f7 100644
--- a/src/DPD-REACT/pair_multi_lucy_rx.cpp
+++ b/src/DPD-REACT/pair_multi_lucy_rx.cpp
@@ -496,7 +496,7 @@ void PairMultiLucyRX::read_table(Table *tb, char *file, char *keyword)
 
   // loop until section found with matching keyword
 
-  while (1) {
+  while (true) {
     if (fgets(line,MAXLINE,fp) == nullptr)
       error->one(FLERR,"Did not find keyword in table file");
     if (strspn(line," \t\n\r") == strlen(line)) continue;  // blank line
diff --git a/src/EXTRA-FIX/fix_gle.cpp b/src/EXTRA-FIX/fix_gle.cpp
index 8f31613188..de225c6980 100644
--- a/src/EXTRA-FIX/fix_gle.cpp
+++ b/src/EXTRA-FIX/fix_gle.cpp
@@ -234,7 +234,7 @@ FixGLE::FixGLE(LAMMPS *lmp, int narg, char **arg) :
 
   char line[MAXLINE],*ptr;
   int n,nwords,ndone=0,eof=0;
-  while (1) {
+  while (true) {
     if (comm->me == 0) {
       ptr = fgets(line,MAXLINE,fgle);
       if (ptr == nullptr) {
@@ -300,7 +300,7 @@ FixGLE::FixGLE(LAMMPS *lmp, int narg, char **arg) :
     ndone = eof = 0;
     const double cfac = force->boltz / force->mvv2e;
 
-    while (1) {
+    while (true) {
       if (comm->me == 0) {
         ptr = fgets(line,MAXLINE,fgle);
         if (ptr == nullptr) {
diff --git a/src/GRANULAR/fix_pour.cpp b/src/GRANULAR/fix_pour.cpp
index b73593b1d7..4c83e13a7b 100644
--- a/src/GRANULAR/fix_pour.cpp
+++ b/src/GRANULAR/fix_pour.cpp
@@ -851,7 +851,7 @@ void FixPour::xyz_random(double h, double *coord)
       coord[2] = h;
     } else {
       double r1,r2;
-      while (1) {
+      while (true) {
         r1 = random->uniform() - 0.5;
         r2 = random->uniform() - 0.5;
         if (r1*r1 + r2*r2 < 0.25) break;
diff --git a/src/KIM/kim_interactions.cpp b/src/KIM/kim_interactions.cpp
index 9a3aee87c0..74ac40198c 100644
--- a/src/KIM/kim_interactions.cpp
+++ b/src/KIM/kim_interactions.cpp
@@ -293,7 +293,7 @@ void KimInteractions::KIM_SET_TYPE_PARAMETERS(const std::string &input_line) con
   char line[MAXLINE], *ptr;
   int n, eof = 0;
 
-  while (1) {
+  while (true) {
     if (comm->me == 0) {
       ptr = fgets(line, MAXLINE,fp);
       if (ptr == nullptr) {
diff --git a/src/KSPACE/pppm.cpp b/src/KSPACE/pppm.cpp
index 9d3a06f18e..06d90e5d0e 100644
--- a/src/KSPACE/pppm.cpp
+++ b/src/KSPACE/pppm.cpp
@@ -983,7 +983,7 @@ void PPPM::set_grid_global()
 
       h = h_x = h_y = h_z = 4.0/g_ewald;
       int count = 0;
-      while (1) {
+      while (true) {
 
         // set grid dimensions
 
diff --git a/src/KSPACE/pppm_dipole.cpp b/src/KSPACE/pppm_dipole.cpp
index 16e06ed13e..abadcc52be 100644
--- a/src/KSPACE/pppm_dipole.cpp
+++ b/src/KSPACE/pppm_dipole.cpp
@@ -783,7 +783,7 @@ void PPPMDipole::set_grid_global()
 
     h = h_x = h_y = h_z = 4.0/g_ewald;
     int count = 0;
-    while (1) {
+    while (true) {
 
       // set grid dimension
 
diff --git a/src/KSPACE/pppm_disp.cpp b/src/KSPACE/pppm_disp.cpp
index fa14cb23f0..85aceb8500 100644
--- a/src/KSPACE/pppm_disp.cpp
+++ b/src/KSPACE/pppm_disp.cpp
@@ -1471,7 +1471,7 @@ int PPPMDisp::qr_alg(double **A, double **Q, int n)
   // start loop for the matrix factorization
   int count = 0;
   int countmax = 100000;
-  while (1) {
+  while (true) {
     // make a Wilkinson shift
     an1 = A[n-2][n-2];
     an = A[n-1][n-1];
@@ -2645,7 +2645,7 @@ void PPPMDisp::set_grid()
   if (!gridflag) {
     h = h_x = h_y = h_z = 4.0/g_ewald;
     int count = 0;
-    while (1) {
+    while (true) {
 
       // set grid dimension
 
@@ -3663,7 +3663,7 @@ void PPPMDisp::set_n_pppm_6()
   // decrease grid spacing until required precision is obtained
 
   int count = 0;
-  while (1) {
+  while (true) {
 
     // set grid dimension
     nx_pppm_6 = static_cast<int> (xprd/h_x);
diff --git a/src/MANIFOLD/fix_nve_manifold_rattle.cpp b/src/MANIFOLD/fix_nve_manifold_rattle.cpp
index b4644a1350..8c3a9205e9 100644
--- a/src/MANIFOLD/fix_nve_manifold_rattle.cpp
+++ b/src/MANIFOLD/fix_nve_manifold_rattle.cpp
@@ -498,7 +498,7 @@ void FixNVEManifoldRattle::rattle_manifold_x(double *x, double *v,
   const double c_inv = 1.0 / c;
 
 
-  while (1) {
+  while (true) {
     v[0] = vt[0] - l*no_dt[0];
     v[1] = vt[1] - l*no_dt[1];
     v[2] = vt[2] - l*no_dt[2];
diff --git a/src/MANYBODY/pair_edip.cpp b/src/MANYBODY/pair_edip.cpp
index 51b38037ab..af2314b8b9 100644
--- a/src/MANYBODY/pair_edip.cpp
+++ b/src/MANYBODY/pair_edip.cpp
@@ -789,7 +789,7 @@ void PairEDIP::read_file(char *file)
   char line[MAXLINE], *ptr;
   int eof = 0;
 
-  while (1) {
+  while (true) {
     if (comm->me == 0) {
       ptr = fgets(line, MAXLINE, fp);
       if (ptr == nullptr) {
diff --git a/src/MANYBODY/pair_edip_multi.cpp b/src/MANYBODY/pair_edip_multi.cpp
index 3cabec4505..8017fa4f8e 100644
--- a/src/MANYBODY/pair_edip_multi.cpp
+++ b/src/MANYBODY/pair_edip_multi.cpp
@@ -602,7 +602,7 @@ void PairEDIPMulti::read_file(char *file)
   char line[MAXLINE],*ptr;
   int eof = 0;
 
-  while (1) {
+  while (true) {
     if (comm->me == 0) {
       ptr = fgets(line,MAXLINE,fp);
       if (ptr == nullptr) {
diff --git a/src/MANYBODY/pair_extep.cpp b/src/MANYBODY/pair_extep.cpp
index bc96a40c57..68db444f31 100644
--- a/src/MANYBODY/pair_extep.cpp
+++ b/src/MANYBODY/pair_extep.cpp
@@ -540,7 +540,7 @@ void PairExTeP::read_file(char *file)
   char line[MAXLINE],*ptr;
   int eof = 0;
 
-  while (1) {
+  while (true) {
     if (comm->me == 0) {
       ptr = fgets(line,MAXLINE,fp);
       if (ptr == nullptr) {
@@ -669,7 +669,7 @@ void PairExTeP::read_file(char *file)
             F_corr_data[iel][jel][in][jn][ivar]=0;
 
   // loop until EOF
-  while (1) {
+  while (true) {
     if (comm->me == 0) {
       ptr = fgets(line,MAXLINE,fp);
       //fputs(line,stdout);
diff --git a/src/MANYBODY/pair_lcbop.cpp b/src/MANYBODY/pair_lcbop.cpp
index 3c6f08a7e7..547fc75154 100644
--- a/src/MANYBODY/pair_lcbop.cpp
+++ b/src/MANYBODY/pair_lcbop.cpp
@@ -935,7 +935,7 @@ void PairLCBOP::read_file(char *filename)
 
     // skip initial comment lines
 
-    while (1) {
+    while (true) {
       utils::sfgets(FLERR,s,MAXLINE,fp,filename,error);
       if (s[0] != '#') break;
     }
@@ -971,7 +971,7 @@ void PairLCBOP::read_file(char *filename)
     utils::sfgets(FLERR,s,MAXLINE,fp,filename,error);    sscanf(s,"%lg",&eps);
     utils::sfgets(FLERR,s,MAXLINE,fp,filename,error);    sscanf(s,"%lg",&delta);
 
-    while (1) {
+    while (true) {
       utils::sfgets(FLERR,s,MAXLINE,fp,filename,error);
       if (s[0] != '#') break;
     }
@@ -988,7 +988,7 @@ void PairLCBOP::read_file(char *filename)
             &F_conj_data[i][2][k][l],
             &F_conj_data[i][3][k][l]);
         }
-        while (1) { utils::sfgets(FLERR,s,MAXLINE,fp,filename,error); if (s[0] != '#') break; }
+        while (true) { utils::sfgets(FLERR,s,MAXLINE,fp,filename,error); if (s[0] != '#') break; }
       }
     }
 
diff --git a/src/MDI/mdi_engine.cpp b/src/MDI/mdi_engine.cpp
index 4be739d187..5194c44189 100644
--- a/src/MDI/mdi_engine.cpp
+++ b/src/MDI/mdi_engine.cpp
@@ -200,7 +200,7 @@ void MDIEngine::command(int narg, char ** /*arg*/)
 
   char *command;
 
-  while (1) {
+  while (true) {
 
     // mdi/engine command only recognizes three nodes
     // DEFAULT, INIT_MD, INIT_OPTG
@@ -265,7 +265,7 @@ char *MDIEngine::mdi_md()
 
   // run MD one step at a time
 
-  while (1) {
+  while (true) {
     update->whichflag = 1;
     timer->init_timeout();
     update->nsteps += 1;
diff --git a/src/MEAM/pair_meam.cpp b/src/MEAM/pair_meam.cpp
index b69d17f0a9..e8c6c942a4 100644
--- a/src/MEAM/pair_meam.cpp
+++ b/src/MEAM/pair_meam.cpp
@@ -517,7 +517,7 @@ void PairMEAM::read_user_meam_file(const std::string &userfile)
   char * line = nullptr;
   char buffer[MAXLINE];
 
-  while (1) {
+  while (true) {
     int which;
     int nindex, index[3];
     double value;
diff --git a/src/MESONT/pair_mesont_tpm.cpp b/src/MESONT/pair_mesont_tpm.cpp
index 425722a569..293e9d02f5 100644
--- a/src/MESONT/pair_mesont_tpm.cpp
+++ b/src/MESONT/pair_mesont_tpm.cpp
@@ -197,7 +197,7 @@ MESONTList::MESONTList(const Atom* atom, const NeighList* nblist) {
       index_list.push_back(i);
       index_list_b[i] = index_list.size() - 1;
       int idx = i;
-      while (1) {
+      while (true) {
         idx = chain_list[idx][1];
         if (idx == cnt_end || idx == domain_end) break;
         else index_list.push_back(idx);
diff --git a/src/MGPT/mgpt_readpot.cpp b/src/MGPT/mgpt_readpot.cpp
index df62bf735d..dd196142f5 100644
--- a/src/MGPT/mgpt_readpot.cpp
+++ b/src/MGPT/mgpt_readpot.cpp
@@ -131,7 +131,7 @@ static void getparmindata(const char *potin_file,int nvol[1],double vol0[1],doub
     exit(1);
   }
 
-  if (0) {
+  if (false) {
     printf("Before sort:\n");
     for (int i = 0; i<n; i++)
       printf("%3d :: %.3f%s",i,volarr[i], (i%5==4) ? "\n" : "  ");
@@ -139,7 +139,7 @@ static void getparmindata(const char *potin_file,int nvol[1],double vol0[1],doub
   }
   qsort(volarr,n,sizeof(double),cmp_double);
 
-  if (0) {
+  if (false) {
     printf("After sort:\n");
     for (int i = 0; i<n; i++)
       printf("%3d :: %.3f%s",i,volarr[i], (i%5==4) ? "\n" : "  ");
@@ -194,7 +194,7 @@ void potdata::readpot(const char *parmin_file,const char *potin_file,const doubl
     int nvol;
     getparmindata(potin_file,&nvol,&vol0,&x0,&x1);
     dx = (x1-x0)/(nvol-1);
-    if (0) {
+    if (false) {
       printf("getparmindata() ==> nvol = %d, vol0 = %.6f, x0= %.6f, x1 = %.6f, dx = %.6f\n",
              nvol,vol0,x0,x1,dx);
     }
@@ -408,7 +408,7 @@ void potdata::readpot(const char *parmin_file,const char *potin_file,const doubl
         double vpair_tmp = vpairtab[i*nr+j];
         vpairtab[i*nr+j] = vpairtab[i*nr+j]*fscr + v2a - v2b;
 
-        if (0) if (fabs(vol-ivol) < 0.01) {
+        if (false) if (fabs(vol-ivol) < 0.01) {
           static FILE *xfile = nullptr;
           if (j == 0) {
             xfile = fopen("mgpt5-pot.dat","w");
@@ -487,7 +487,7 @@ void potdata::readpot(const char *parmin_file,const char *potin_file,const doubl
   evalspline(nx-1,x0,x1,C,x,&evol0,&devol0,&unused);
   devol0 *= dxdv;
 
-  if (1) {
+  if (true) {
     printf("%% READPOT PARAMETERS:\n");
 
     printf("%% ddl = %15.5e  %15.5e  %15.5e  %15.5e\n",ddl[1],ddl[2],ddl[3],ddl[4]);
diff --git a/src/MGPT/mgpt_splinetab.cpp b/src/MGPT/mgpt_splinetab.cpp
index e31572fe50..fd6d4541c2 100644
--- a/src/MGPT/mgpt_splinetab.cpp
+++ b/src/MGPT/mgpt_splinetab.cpp
@@ -105,7 +105,7 @@ void evalspline(int n,double x0,double x1,double C[][4],
   xhat = xhat - idx;
   p = C[idx];
 
-  if (0) {
+  if (false) {
     *y = p[0] + xhat*(p[1] + xhat*(p[2] + xhat*p[3]));
 
     *dy = p[1] + xhat*(2*p[2] + xhat*3*p[3]);
diff --git a/src/MGPT/pair_mgpt.cpp b/src/MGPT/pair_mgpt.cpp
index 2bea1273c6..fde6fc7084 100644
--- a/src/MGPT/pair_mgpt.cpp
+++ b/src/MGPT/pair_mgpt.cpp
@@ -191,7 +191,7 @@ static inline double mtrace(int n,double A[8][8],double B[8][8]) {
 
 void PairMGPT::make_triplet(bond_data *ij_bond,bond_data *ik_bond,
                              triplet_data *triptr) {
-  if (1) {
+  if (true) {
     const trmul_fun tr_mul = linalg.tr_mul;
     tr_mul(&(ij_bond->H.m[1][0]), &(ik_bond->H.m[1][0]) ,&(triptr->H1H2.m[1][0]) );
     tr_mul(&(ij_bond->Hx.m[1][0]),&(ik_bond->H.m[1][0]) ,&(triptr->H1xH2.m[1][0]));
@@ -289,7 +289,7 @@ double PairMGPT::numderiv3t(double xx[][3],int i,int j,int k,int p) {
 
   xx[i][p] = xsave - delta;
   make_bond(xx,i,j,&Bij);
-  if (0) { /* This bond doesn't change when i is perturbed */
+  if (false) { /* This bond doesn't change when i is perturbed */
     make_bond(xx,j,k,&Bjk);
   }
   make_bond(xx,k,i,&Bki);
@@ -341,7 +341,7 @@ double PairMGPT::numderiv4(double xx[][3],int i,int j,int k,int m,int p) {
 
   xx[i][p] = xsave - delta;
   make_bond(xx,i,j,&Bij);
-  if (0) { /* Only the i coordinates changed... */
+  if (false) { /* Only the i coordinates changed... */
     make_bond(xx,j,k,&Bjk);
     make_bond(xx,k,m,&Bkm);
   }
@@ -438,7 +438,7 @@ void PairMGPT::force_debug_4(double xx[][3],
   for (int p = 0; p<3; p++) {
     /* Compute numerical derivatives by displacing atoms i,j,k,m */
     double ndfi,ndfj,ndfk,ndfm;
-    if (1) {
+    if (true) {
       double ndf[] = {0.0,0.0,0.0,0.0};
       for (int s = 0; s<4; s++)
         for (int t = 0; t<4; t++)
@@ -765,7 +765,7 @@ void PairMGPT::compute_x(const int *nnei,const int * const *nlist,
 
   int c_p = 0, c_t = 0, c_q = 0;
 
-  if (0)
+  if (false)
     if (domain->triclinic) {
       if (comm->me == 0)
         printf("Can not handle triclinic box yet\n");
@@ -1690,7 +1690,7 @@ void PairMGPT::compute(int eflag, int vflag)
 
   compute_x(listfull->numneigh,listfull->firstneigh,&e_s,&e_p,&e_t,&e_q,evflag,newton_pair);
 
-  if (0) { // Stupid force calculation / verification
+  if (false) { // Stupid force calculation / verification
     int ii,nmax=-1;
     for (ii = 0; ii<listfull->inum + listfull->gnum; ii++) {
       int i = listfull->ilist[ii];
@@ -1768,7 +1768,7 @@ void PairMGPT::compute(int eflag, int vflag)
   }
 
 
-  if (0) {
+  if (false) {
     printf("\nForces MGPT:\n");
     const int iimax = (listfull->inum < 10) ? listfull->inum : 10;
     for (int ii = 0; ii<iimax; ii++) {
diff --git a/src/ML-IAP/mliap_descriptor_snap.cpp b/src/ML-IAP/mliap_descriptor_snap.cpp
index 6399ef63a3..5475117a99 100644
--- a/src/ML-IAP/mliap_descriptor_snap.cpp
+++ b/src/ML-IAP/mliap_descriptor_snap.cpp
@@ -382,7 +382,7 @@ void MLIAPDescriptorSNAP::read_paramfile(char *paramfilename)
   int eof = 0;
   int n,nwords;
 
-  while (1) {
+  while (true) {
     if (comm->me == 0) {
       ptr = fgets(line,MAXLINE,fpparam);
       if (ptr == nullptr) {
diff --git a/src/ML-IAP/mliap_descriptor_so3.cpp b/src/ML-IAP/mliap_descriptor_so3.cpp
index d816bd0638..e8bedea377 100644
--- a/src/ML-IAP/mliap_descriptor_so3.cpp
+++ b/src/ML-IAP/mliap_descriptor_so3.cpp
@@ -93,7 +93,7 @@ void MLIAPDescriptorSO3::read_paramfile(char *paramfilename)
   int eof = 0;
   int n, nwords;
 
-  while (1) {
+  while (true) {
     if (comm->me == 0) {
       ptr = utils::fgets_trunc(line, MAXLINE, fpparam);
       if (ptr == nullptr) {
diff --git a/src/ML-IAP/mliap_model_nn.cpp b/src/ML-IAP/mliap_model_nn.cpp
index 10ef97300e..853f1d9c6c 100644
--- a/src/ML-IAP/mliap_model_nn.cpp
+++ b/src/ML-IAP/mliap_model_nn.cpp
@@ -125,7 +125,7 @@ void MLIAPModelNN::read_coeffs(char *coefffilename)
   int ielem = 0;
   int l = 0;
 
-  while (1) {
+  while (true) {
     if (comm->me == 0) {
       ptr = fgets(line,MAXLINE,fpcoeff);
       if (ptr == nullptr) {
diff --git a/src/ML-RANN/pair_rann.cpp b/src/ML-RANN/pair_rann.cpp
index fbc54e745f..3e97b638dc 100644
--- a/src/ML-RANN/pair_rann.cpp
+++ b/src/ML-RANN/pair_rann.cpp
@@ -440,7 +440,7 @@ void PairRANN::read_mass(const std::vector<std::string> &line1, const std::vecto
   if (nelements == -1)error->one(filename,linenum-1,"atom types must be defined before mass in potential file.");
   for (int i=0;i<nelements;i++) {
     if (line1[1].compare(elements[i])==0) {
-      mass[i]=utils::numeric(filename,linenum,line2[0].c_str(),1,lmp);
+      mass[i]=utils::numeric(filename,linenum,line2[0].c_str(),true,lmp);
       return;
     }
   }
@@ -452,7 +452,7 @@ void PairRANN::read_fpe(std::vector<std::string> line,std::vector<std::string> l
   if (nelements == -1)error->one(filename,linenum-1,"atom types must be defined before fingerprints per element in potential file.");
   for (i=0;i<nelementsp;i++) {
     if (line[1].compare(elementsp[i])==0) {
-      fingerprintperelement[i] = utils::inumeric(filename,linenum,line1[0].c_str(),1,lmp);
+      fingerprintperelement[i] = utils::inumeric(filename,linenum,line1[0].c_str(),true,lmp);
       fingerprints[i] = new RANN::Fingerprint *[fingerprintperelement[i]];
       for (int j=0;j<fingerprintperelement[i];j++) {
         fingerprints[i][j]=new RANN::Fingerprint(this);
@@ -491,7 +491,7 @@ void PairRANN::read_fingerprints(std::vector<std::string> line,std::vector<std::
     fingerprints[i][i1] = create_fingerprint(line1[k].c_str());
     if (fingerprints[i][i1]->n_body_type!=nwords-1) {error->one(filename,linenum,"invalid fingerprint for element combination");}
     k++;
-    fingerprints[i][i1]->init(atomtypes,utils::inumeric(filename,linenum,line1[k++].c_str(),1,lmp));
+    fingerprints[i][i1]->init(atomtypes,utils::inumeric(filename,linenum,line1[k++].c_str(),true,lmp));
     fingerprintcount[i]++;
   }
   delete[] atomtypes;
@@ -523,7 +523,7 @@ void PairRANN::read_fingerprint_constants(std::vector<std::string> line,std::vec
     for (j=0;j<n_body_type;j++) {
       if (fingerprints[i][k]->atomtypes[j]!=atomtypes[j]) {break;}
       if (j==n_body_type-1) {
-        if (line[nwords-3].compare(fingerprints[i][k]->style)==0 && utils::inumeric(filename,linenum,line[nwords-2].c_str(),1,lmp)==fingerprints[i][k]->id) {
+        if (line[nwords-3].compare(fingerprints[i][k]->style)==0 && utils::inumeric(filename,linenum,line[nwords-2].c_str(),true,lmp)==fingerprints[i][k]->id) {
           found=true;
           i1 = k;
           break;
@@ -542,7 +542,7 @@ void PairRANN::read_network_layers(std::vector<std::string> line,std::vector<std
   if (nelements == -1)error->one(filename,linenum-1,"atom types must be defined before network layers in potential file.");
   for (i=0;i<nelements;i++) {
     if (line[1].compare(elements[i])==0) {
-      net[i].layers = utils::inumeric(filename,linenum,line1[0].c_str(),1,lmp);
+      net[i].layers = utils::inumeric(filename,linenum,line1[0].c_str(),true,lmp);
       if (net[i].layers < 1)error->one(filename,linenum,"invalid number of network layers");
       delete[] net[i].dimensions;
       weightdefined[i] = new bool [net[i].layers];
@@ -570,9 +570,9 @@ void PairRANN::read_layer_size(std::vector<std::string> line,std::vector<std::st
   for (i=0;i<nelements;i++) {
     if (line[1].compare(elements[i])==0) {
       if (net[i].layers==0)error->one(filename,linenum-1,"networklayers for each atom type must be defined before the corresponding layer sizes.");
-      int j = utils::inumeric(filename,linenum,line[2].c_str(),1,lmp);
+      int j = utils::inumeric(filename,linenum,line[2].c_str(),true,lmp);
       if (j>=net[i].layers || j<0) {error->one(filename,linenum,"invalid layer in layer size definition");};
-      net[i].dimensions[j]= utils::inumeric(filename,linenum,line1[0].c_str(),1,lmp);
+      net[i].dimensions[j]= utils::inumeric(filename,linenum,line1[0].c_str(),true,lmp);
       return;
     }
   }
@@ -587,7 +587,7 @@ void PairRANN::read_weight(std::vector<std::string> line,std::vector<std::string
   for (l=0;l<nelements;l++) {
     if (line[1].compare(elements[l])==0) {
       if (net[l].layers==0)error->one(filename,*linenum-1,"networklayers must be defined before weights.");
-      i=utils::inumeric(filename,*linenum,line[2].c_str(),1,lmp);
+      i=utils::inumeric(filename,*linenum,line[2].c_str(),true,lmp);
       if (i>=net[l].layers || i<0)error->one(filename,*linenum-1,"invalid weight layer");
       if (net[l].dimensions[i]==0 || net[l].dimensions[i+1]==0) error->one(filename,*linenum-1,"network layer sizes must be defined before corresponding weight");
       net[l].Weights[i] = new double[net[l].dimensions[i]*net[l].dimensions[i+1]];
@@ -595,7 +595,7 @@ void PairRANN::read_weight(std::vector<std::string> line,std::vector<std::string
       nwords = line1.size();
       if (nwords != net[l].dimensions[i])error->one(filename,*linenum,"invalid weights per line");
       for (k=0;k<net[l].dimensions[i];k++) {
-        net[l].Weights[i][k] = utils::numeric(filename,*linenum,line1[k].c_str(),1,lmp);
+        net[l].Weights[i][k] = utils::numeric(filename,*linenum,line1[k].c_str(),true,lmp);
       }
       for (j=1;j<net[l].dimensions[i+1];j++) {
         ptr = fgets(linetemp,longline,fp);
@@ -606,7 +606,7 @@ void PairRANN::read_weight(std::vector<std::string> line,std::vector<std::string
         nwords = line1.size();
         if (nwords != net[l].dimensions[i])error->one(filename,*linenum,"invalid weights per line");
         for (k=0;k<net[l].dimensions[i];k++) {
-          net[l].Weights[i][j*net[l].dimensions[i]+k] = utils::numeric(filename,*linenum,line1[k].c_str(),1,lmp);
+          net[l].Weights[i][j*net[l].dimensions[i]+k] = utils::numeric(filename,*linenum,line1[k].c_str(),true,lmp);
         }
       }
       return;
@@ -621,19 +621,19 @@ void PairRANN::read_bias(std::vector<std::string> line,std::vector<std::string>
   for (l=0;l<nelements;l++) {
     if (line[1].compare(elements[l])==0) {
       if (net[l].layers==0)error->one(filename,*linenum-1,"networklayers must be defined before biases.");
-      i=utils::inumeric(filename,*linenum,line[2].c_str(),1,lmp);
+      i=utils::inumeric(filename,*linenum,line[2].c_str(),true,lmp);
       if (i>=net[l].layers || i<0)error->one(filename,*linenum-1,"invalid bias layer");
       if (net[l].dimensions[i]==0) error->one(filename,*linenum-1,"network layer sizes must be defined before corresponding bias");
       biasdefined[l][i] = true;
       net[l].Biases[i] = new double[net[l].dimensions[i+1]];
-      net[l].Biases[i][0] = utils::numeric(filename,*linenum,line1[0].c_str(),1,lmp);
+      net[l].Biases[i][0] = utils::numeric(filename,*linenum,line1[0].c_str(),true,lmp);
       for (j=1;j<net[l].dimensions[i+1];j++) {
         ptr=fgets(linetemp,MAXLINE,fp);
         if (ptr==nullptr)error->one(filename,*linenum,"unexpected end of potential file!");
         (*linenum)++;
         Tokenizer values1 = Tokenizer(linetemp,": ,\t_\n");
         line1 = values1.as_vector();
-        net[l].Biases[i][j] = utils::numeric(filename,*linenum,line1[0].c_str(),1,lmp);
+        net[l].Biases[i][j] = utils::numeric(filename,*linenum,line1[0].c_str(),true,lmp);
       }
       return;
     }
@@ -680,10 +680,10 @@ void PairRANN::read_screening(std::vector<std::string> line,std::vector<std::str
   k = atomtypes[2];
   int index = i*nelements*nelements+j*nelements+k;
   if (line[4].compare("Cmin")==0)  {
-    screening_min[index] = utils::numeric(filename,linenum,line1[0].c_str(),1,lmp);
+    screening_min[index] = utils::numeric(filename,linenum,line1[0].c_str(),true,lmp);
   }
   else if (line[4].compare("Cmax")==0) {
-    screening_max[index] = utils::numeric(filename,linenum,line1[0].c_str(),1,lmp);
+    screening_max[index] = utils::numeric(filename,linenum,line1[0].c_str(),true,lmp);
   }
   else error->one(filename,linenum-1,"unrecognized screening keyword");
   delete[] atomtypes;
diff --git a/src/ML-SNAP/pair_snap.cpp b/src/ML-SNAP/pair_snap.cpp
index d6da639734..1eb078bc61 100644
--- a/src/ML-SNAP/pair_snap.cpp
+++ b/src/ML-SNAP/pair_snap.cpp
@@ -640,7 +640,7 @@ void PairSNAP::read_files(char *coefffilename, char *paramfilename)
   }
 
   eof = 0;
-  while (1) {
+  while (true) {
     if (comm->me == 0) {
       ptr = fgets(line,MAXLINE,fpparam);
       if (ptr == nullptr) {
diff --git a/src/POEMS/fix_poems.cpp b/src/POEMS/fix_poems.cpp
index fdd8ef7a18..201e40b5b8 100644
--- a/src/POEMS/fix_poems.cpp
+++ b/src/POEMS/fix_poems.cpp
@@ -954,7 +954,7 @@ void FixPOEMS::readfile(char *file)
   int nlocal = atom->nlocal;
   int i,id,nlen;
 
-  while (1) {
+  while (true) {
     if (me == 0) nlen = readline(fp,&line,&maxline);
     MPI_Bcast(&nlen,1,MPI_INT,0,world);
     if (nlen == 0) break;
@@ -986,7 +986,7 @@ int FixPOEMS::readline(FILE *fp, char **pline, int *pmaxline)
   char *line = *pline;
   int maxline = *pmaxline;
 
-  while (1) {
+  while (true) {
     if (n+1 >= maxline) {
       maxline += DELTA;
       memory->grow(line,maxline,"fix_poems:line");
@@ -1246,7 +1246,7 @@ int FixPOEMS::loopcheck(int nvert, int nedge, tagint **elist)
   int *stack = new int[nvert];
   ncluster = 0;
 
-  while (1) {
+  while (true) {
     for (i = 0; i < nvert; i++)
       if (mark[i] == 0) break;
     if (i == nvert) break;
diff --git a/src/PTM/ptm_convex_hull_incremental.cpp b/src/PTM/ptm_convex_hull_incremental.cpp
index 580d88c578..23b8e3a89d 100644
--- a/src/PTM/ptm_convex_hull_incremental.cpp
+++ b/src/PTM/ptm_convex_hull_incremental.cpp
@@ -263,7 +263,7 @@ int get_convex_hull(int num_points, const double (*points)[3], convexhull_t* ch,
         int ret = 0;
         int num_prev = ch->num_prev;
         ch->num_prev = num_points;
-        if (!ch->ok || 0)
+        if (!ch->ok || false)
         {
                 ret = initialize_convex_hull(num_points, points, ch->facets, ch->plane_normal, ch->processed, ch->initial_vertices, ch->barycentre);
                 if (ret != 0)
diff --git a/src/QEQ/fix_qeq.cpp b/src/QEQ/fix_qeq.cpp
index 79205f7c81..51262d7dc7 100644
--- a/src/QEQ/fix_qeq.cpp
+++ b/src/QEQ/fix_qeq.cpp
@@ -763,7 +763,7 @@ void FixQEq::read_file(char *file)
                                        " {}", file,utils::getsyserror()));
       TextFileReader reader(fp, "qeq parameter");
 
-      while (1) {
+      while (true) {
         auto values = reader.next_values(0);
 
         if (values.count() == 0) continue;
diff --git a/src/REACTION/fix_bond_react.cpp b/src/REACTION/fix_bond_react.cpp
index bddeb330e4..d106c858b4 100644
--- a/src/REACTION/fix_bond_react.cpp
+++ b/src/REACTION/fix_bond_react.cpp
@@ -3763,7 +3763,7 @@ void FixBondReact::read(int myrxn)
   // stop when read an unrecognized line
 
   ncreate = 0;
-  while (1) {
+  while (true) {
 
     readline(line);
 
diff --git a/src/REAXFF/fix_reaxff_species.cpp b/src/REAXFF/fix_reaxff_species.cpp
index 3c8e808f93..a839469d35 100644
--- a/src/REAXFF/fix_reaxff_species.cpp
+++ b/src/REAXFF/fix_reaxff_species.cpp
@@ -416,12 +416,12 @@ void FixReaxFFSpecies::FindMolecule ()
   }
 
   loop = 0;
-  while (1) {
+  while (true) {
     comm->forward_comm_fix(this);
     loop ++;
 
     change = 0;
-    while (1) {
+    while (true) {
       done = 1;
 
       for (ii = 0; ii < inum; ii++) {
diff --git a/src/REAXFF/reaxff_allocate.cpp b/src/REAXFF/reaxff_allocate.cpp
index cbb53420ba..b81b8ed222 100644
--- a/src/REAXFF/reaxff_allocate.cpp
+++ b/src/REAXFF/reaxff_allocate.cpp
@@ -232,13 +232,13 @@ namespace ReaxFF {
     reallocate_data *wsr = &(workspace->realloc);
 
     if (system->n >= DANGER_ZONE * system->local_cap ||
-        (0 && system->n <= LOOSE_ZONE * system->local_cap)) {
+        (false && system->n <= LOOSE_ZONE * system->local_cap)) {
       system->local_cap = MAX((int)(system->n * safezone), mincap);
     }
 
     int Nflag = 0;
     if (system->N >= DANGER_ZONE * system->total_cap ||
-        (0 && system->N <= LOOSE_ZONE * system->total_cap)) {
+        (false && system->N <= LOOSE_ZONE * system->total_cap)) {
       Nflag = 1;
       system->total_cap = MAX((int)(system->N * safezone), mincap);
     }
@@ -272,7 +272,7 @@ namespace ReaxFF {
     if (control->hbond_cut > 0) {
       Hflag = 0;
       if (system->numH >= DANGER_ZONE * system->Hcap ||
-          (0 && system->numH <= LOOSE_ZONE * system->Hcap)) {
+          (false && system->numH <= LOOSE_ZONE * system->Hcap)) {
         Hflag = 1;
         system->Hcap = int(MAX(system->numH * saferzone, mincap));
       }
diff --git a/src/REAXFF/reaxff_control.cpp b/src/REAXFF/reaxff_control.cpp
index 2020e8a5c3..3ee7614366 100644
--- a/src/REAXFF/reaxff_control.cpp
+++ b/src/REAXFF/reaxff_control.cpp
@@ -81,7 +81,7 @@ namespace ReaxFF {
       LAMMPS_NS::TextFileReader reader(control_file, "ReaxFF control");
       reader.ignore_comments = false;
 
-      while (1) {
+      while (true) {
         auto values = reader.next_values(0);
 
         // empty line
diff --git a/src/REPLICA/fix_hyper_local.cpp b/src/REPLICA/fix_hyper_local.cpp
index ba91644c53..b506ef4f4a 100644
--- a/src/REPLICA/fix_hyper_local.cpp
+++ b/src/REPLICA/fix_hyper_local.cpp
@@ -980,7 +980,7 @@ void FixHyperLocal::build_bond_list(int natom)
                                          "hyper/local:clist");
   }
 
-  while (1) {
+  while (true) {
     if (firstflag) break;
     for (i = 0; i < nall; i++) numcoeff[i] = 0;
     for (i = 0; i < nall; i++) clist[i] = nullptr;
diff --git a/src/REPLICA/neb.cpp b/src/REPLICA/neb.cpp
index 8cfc4b5c24..e730aac351 100644
--- a/src/REPLICA/neb.cpp
+++ b/src/REPLICA/neb.cpp
@@ -392,7 +392,7 @@ void NEB::readfile(char *file, int flag)
   if (flag == 0) {
     if (me_universe == 0) {
       open(file);
-      while (1) {
+      while (true) {
         eof = fgets(line,MAXLINE,fp);
         if (eof == nullptr) error->one(FLERR,"Unexpected end of NEB file");
         start = &line[strspn(line," \t\n\v\f\r")];
@@ -408,7 +408,7 @@ void NEB::readfile(char *file, int flag)
     if (me == 0) {
       if (ireplica) {
         open(file);
-        while (1) {
+        while (true) {
           eof = fgets(line,MAXLINE,fp);
           if (eof == nullptr) error->one(FLERR,"Unexpected end of NEB file");
           start = &line[strspn(line," \t\n\v\f\r")];
diff --git a/src/RIGID/fix_rigid.cpp b/src/RIGID/fix_rigid.cpp
index db9767d01e..9c39518508 100644
--- a/src/RIGID/fix_rigid.cpp
+++ b/src/RIGID/fix_rigid.cpp
@@ -2281,7 +2281,7 @@ void FixRigid::readfile(int which, double *vec,
     if (fp == nullptr)
       error->one(FLERR,"Cannot open fix rigid file {}: {}",
                                    inpfile,utils::getsyserror());
-    while (1) {
+    while (true) {
       eof = fgets(line,MAXLINE,fp);
       if (eof == nullptr) error->one(FLERR,"Unexpected end of fix rigid file");
       start = &line[strspn(line," \t\n\v\f\r")];
diff --git a/src/RIGID/fix_rigid_small.cpp b/src/RIGID/fix_rigid_small.cpp
index 0ef05d926c..5db24a96d5 100644
--- a/src/RIGID/fix_rigid_small.cpp
+++ b/src/RIGID/fix_rigid_small.cpp
@@ -2451,7 +2451,7 @@ void FixRigidSmall::readfile(int which, double **array, int *inbody)
     if (fp == nullptr)
       error->one(FLERR,"Cannot open fix rigid/small file {}: {}",
                                    inpfile,utils::getsyserror());
-    while (1) {
+    while (true) {
       eof = fgets(line,MAXLINE,fp);
       if (eof == nullptr)
         error->one(FLERR,"Unexpected end of fix rigid/small file");
diff --git a/src/SPIN/neb_spin.cpp b/src/SPIN/neb_spin.cpp
index 1c987f8e7e..0ed3ad28c3 100644
--- a/src/SPIN/neb_spin.cpp
+++ b/src/SPIN/neb_spin.cpp
@@ -387,7 +387,7 @@ void NEBSpin::readfile(char *file, int flag)
   if (flag == 0) {
     if (me_universe == 0) {
       open(file);
-      while (1) {
+      while (true) {
         eof = fgets(line,MAXLINE,fp);
         if (eof == nullptr) error->one(FLERR,"Unexpected end of neb/spin file");
         start = &line[strspn(line," \t\n\v\f\r")];
@@ -401,7 +401,7 @@ void NEBSpin::readfile(char *file, int flag)
     if (me == 0) {
       if (ireplica) {
         open(file);
-        while (1) {
+        while (true) {
           eof = fgets(line,MAXLINE,fp);
           if (eof == nullptr) error->one(FLERR,"Unexpected end of neb/spin file");
           start = &line[strspn(line," \t\n\v\f\r")];
diff --git a/src/SRD/fix_srd.cpp b/src/SRD/fix_srd.cpp
index f1e17eaa24..48d7d55663 100644
--- a/src/SRD/fix_srd.cpp
+++ b/src/SRD/fix_srd.cpp
@@ -1433,7 +1433,7 @@ void FixSRD::collisions_multi()
     jlast = -1;
     dt = dt_big;
 
-    while (1) {
+    while (true) {
       nbig = nbinbig[ibin];
       if (ibounce == 0) ncheck += nbig;
 
@@ -2263,7 +2263,7 @@ void FixSRD::slip(double *vs, double *vb, double *xb, Big *big, double *xsurf, d
   double tangent[3], vsurf[3];
   double *omega = big->omega;
 
-  while (1) {
+  while (true) {
     r1 = sigma * random->gaussian();
     r2 = sigma * random->gaussian();
     vnmag = sqrt(r1 * r1 + r2 * r2);
@@ -2319,7 +2319,7 @@ void FixSRD::slip_wall(double *vs, int iwall, double *norm, double *vsnew)
   tangent2[1] = norm[2] * tangent1[0] - norm[0] * tangent1[2];
   tangent2[2] = norm[0] * tangent1[1] - norm[1] * tangent1[0];
 
-  while (1) {
+  while (true) {
     r1 = sigma * random->gaussian();
     r2 = sigma * random->gaussian();
     vnmag = sqrt(r1 * r1 + r2 * r2);
@@ -2370,7 +2370,7 @@ void FixSRD::noslip(double *vs, double *vb, double *xb, Big *big, int iwall, dou
   tangent2[1] = norm[2] * tangent1[0] - norm[0] * tangent1[2];
   tangent2[2] = norm[0] * tangent1[1] - norm[1] * tangent1[0];
 
-  while (1) {
+  while (true) {
     r1 = sigma * random->gaussian();
     r2 = sigma * random->gaussian();
     vnmag = sqrt(r1 * r1 + r2 * r2);
diff --git a/src/atom.cpp b/src/atom.cpp
index 796c0ba156..8bf361ab95 100644
--- a/src/atom.cpp
+++ b/src/atom.cpp
@@ -1904,7 +1904,7 @@ void Atom::add_molecule(int narg, char **arg)
 
   int ifile = 1;
   int index = 1;
-  while (1) {
+  while (true) {
     molecules = (Molecule **)
       memory->srealloc(molecules,(nmolecule+1)*sizeof(Molecule *),
                        "atom::molecules");
diff --git a/src/atom_vec_body.cpp b/src/atom_vec_body.cpp
index a1ef126069..6308153be6 100644
--- a/src/atom_vec_body.cpp
+++ b/src/atom_vec_body.cpp
@@ -105,7 +105,7 @@ void AtomVecBody::process_args(int narg, char **arg)
 
   if (narg < 1) error->all(FLERR,"Invalid atom_style body command");
 
-  if (0) {
+  if (false) {
     bptr = nullptr;
 
 #define BODY_CLASS
diff --git a/src/balance.cpp b/src/balance.cpp
index bd3ba007ef..3f325dffe6 100644
--- a/src/balance.cpp
+++ b/src/balance.cpp
@@ -930,7 +930,7 @@ int Balance::shift()
         // else add split I-1 or J+1 to set and try again
         // delta = size of expanded split set that will satisy criterion
 
-        while (1) {
+        while (true) {
           delta = (j-i) * close;
           midpt = 0.5 * (split[i]+split[j]);
           start = midpt - 0.5*delta;
diff --git a/src/comm_tiled.cpp b/src/comm_tiled.cpp
index 482b90c4c2..28ef37b008 100644
--- a/src/comm_tiled.cpp
+++ b/src/comm_tiled.cpp
@@ -1884,7 +1884,7 @@ void CommTiled::box_drop_brick(int idim, double *lo, double *hi, int &indexme)
   if (index < 0 || index > procgrid[idim])
     error->one(FLERR,"Comm tiled invalid index in box drop brick");
 
-  while (1) {
+  while (true) {
     lower = boxlo[idim] + prd[idim]*split[index];
     if (index < procgrid[idim]-1)
       upper = boxlo[idim] + prd[idim]*split[index+1];
diff --git a/src/compute_aggregate_atom.cpp b/src/compute_aggregate_atom.cpp
index 818d8657b8..cb39f61ce0 100644
--- a/src/compute_aggregate_atom.cpp
+++ b/src/compute_aggregate_atom.cpp
@@ -166,7 +166,7 @@ void ComputeAggregateAtom::compute_peratom()
 
   int change,done,anychange;
 
-  while (1) {
+  while (true) {
     comm->forward_comm_compute(this);
 
     // reverse communication when bonds are not stored on every processor
@@ -175,7 +175,7 @@ void ComputeAggregateAtom::compute_peratom()
       comm->reverse_comm_compute(this);
 
     change = 0;
-    while (1) {
+    while (true) {
       done = 1;
       for (i = 0; i < nlocal; i++) {
         if (!(mask[i] & groupbit)) continue;
diff --git a/src/compute_cluster_atom.cpp b/src/compute_cluster_atom.cpp
index 476af0bfa2..ca3fe1f453 100644
--- a/src/compute_cluster_atom.cpp
+++ b/src/compute_cluster_atom.cpp
@@ -164,11 +164,11 @@ void ComputeClusterAtom::compute_peratom()
 
   int change,done,anychange;
 
-  while (1) {
+  while (true) {
     comm->forward_comm_compute(this);
 
     change = 0;
-    while (1) {
+    while (true) {
       done = 1;
       for (ii = 0; ii < inum; ii++) {
         i = ilist[ii];
diff --git a/src/compute_fragment_atom.cpp b/src/compute_fragment_atom.cpp
index 9ed57fef60..d361e29d41 100644
--- a/src/compute_fragment_atom.cpp
+++ b/src/compute_fragment_atom.cpp
@@ -150,7 +150,7 @@ void ComputeFragmentAtom::compute_peratom()
 
   int iteration = 0;
 
-  while (1) {
+  while (true) {
     iteration++;
 
     comm->forward_comm_compute(this);
diff --git a/src/create_atoms.cpp b/src/create_atoms.cpp
index e82be7d331..f21d1fc23d 100644
--- a/src/create_atoms.cpp
+++ b/src/create_atoms.cpp
@@ -693,7 +693,7 @@ void CreateAtoms::add_random()
 
   int valid;
   for (int i = 0; i < nrandom; i++) {
-    while (1) {
+    while (true) {
       xone[0] = xlo + random->uniform() * (xhi-xlo);
       xone[1] = ylo + random->uniform() * (yhi-ylo);
       xone[2] = zlo + random->uniform() * (zhi-zlo);
diff --git a/src/input.cpp b/src/input.cpp
index 21c092f356..08f62bdb42 100644
--- a/src/input.cpp
+++ b/src/input.cpp
@@ -180,7 +180,7 @@ void Input::file()
 {
   int m,n;
 
-  while (1) {
+  while (true) {
 
     // read a line from input script
     // n = length of line including str terminator, 0 if end of file
@@ -189,7 +189,7 @@ void Input::file()
     if (me == 0) {
 
       m = 0;
-      while (1) {
+      while (true) {
 
         if (infile == nullptr) {
           n = 0;
diff --git a/src/min_linesearch.cpp b/src/min_linesearch.cpp
index a5d0aa326c..c4c10d8a1f 100644
--- a/src/min_linesearch.cpp
+++ b/src/min_linesearch.cpp
@@ -253,7 +253,7 @@ int MinLineSearch::linemin_backtrack(double eoriginal, double &alpha)
 
   // backtrack with alpha until energy decrease is sufficient
 
-  while (1) {
+  while (true) {
     ecurrent = alpha_step(alpha,1);
 
     // if energy change is better than ideal, exit with success
@@ -412,7 +412,7 @@ int MinLineSearch::linemin_quadratic(double eoriginal, double &alpha)
   //        etmp-eoriginal+alphatmp*fdothall);
   // alpha_step(0.0,1);
 
-  while (1) {
+  while (true) {
     ecurrent = alpha_step(alpha,1);
 
     // compute new fh, alpha, delfh
@@ -708,7 +708,7 @@ int MinLineSearch::linemin_forcezero(double eoriginal, double &alpha)
 
   // main linesearch loop
 
-  while (1) {
+  while (true) {
     backtrack = false;
     fhPrev = fhCurr;
     engPrev = engCurr;
diff --git a/src/molecule.cpp b/src/molecule.cpp
index 2c9b03337d..40ca218ecc 100644
--- a/src/molecule.cpp
+++ b/src/molecule.cpp
@@ -412,7 +412,7 @@ void Molecule::read(int flag)
   // skip blank lines or lines that start with "#"
   // stop when read an unrecognized line
 
-  while (1) {
+  while (true) {
 
     readline(line);
 
diff --git a/src/platform.cpp b/src/platform.cpp
index 555026b2ac..f589efc318 100644
--- a/src/platform.cpp
+++ b/src/platform.cpp
@@ -231,7 +231,7 @@ std::string platform::os_info()
   if (platform::file_is_readable("/etc/os-release")) {
     try {
         TextFileReader reader("/etc/os-release","");
-        while (1) {
+        while (true) {
           auto words = reader.next_values(0,"=");
           if ((words.count() > 1) && (words.next_string() == "PRETTY_NAME")) {
             buf += " " + utils::trim(words.next_string());
diff --git a/src/procmap.cpp b/src/procmap.cpp
index ed3839fe7b..3fc8a2263e 100644
--- a/src/procmap.cpp
+++ b/src/procmap.cpp
@@ -294,7 +294,7 @@ void ProcMap::custom_grid(char *cfile, int nprocs,
     char *ptr;
     if (!fgets(line,MAXLINE,fp))
       error->one(FLERR,"Unexpected end of custom file");
-    while (1) {
+    while (true) {
       if ((ptr = strchr(line,'#'))) *ptr = '\0';
       if (strspn(line," \t\n\r") != strlen(line)) break;
       if (!fgets(line,MAXLINE,fp))
diff --git a/src/rcb.cpp b/src/rcb.cpp
index b4d1c135ec..92eafebc28 100644
--- a/src/rcb.cpp
+++ b/src/rcb.cpp
@@ -285,7 +285,7 @@ void RCB::compute(int dimension, int n, double **x, double *wt,
       first_iteration = 1;
       indexlo = indexhi = 0;
 
-      while (1) {
+      while (true) {
 
         // choose bisector value
         // use old value on 1st iteration if old cut dimension is the same
@@ -814,7 +814,7 @@ void RCB::compute_old(int dimension, int n, double **x, double *wt,
     first_iteration = 1;
     indexlo = indexhi = 0;
 
-    while (1) {
+    while (true) {
 
       // choose bisector value
       // use old value on 1st iteration if old cut dimension is the same
diff --git a/src/read_data.cpp b/src/read_data.cpp
index edbfc16696..0c7af243ac 100644
--- a/src/read_data.cpp
+++ b/src/read_data.cpp
@@ -430,7 +430,7 @@ void ReadData::command(int narg, char **arg)
   nlocal_previous = atom->nlocal;
   int firstpass = 1;
 
-  while (1) {
+  while (true) {
 
     // open file on proc 0
 
@@ -965,7 +965,7 @@ void ReadData::header(int firstpass)
     if (eof == nullptr) error->one(FLERR,"Unexpected end of data file");
   }
 
-  while (1) {
+  while (true) {
 
     // read a line and bcast length
 
diff --git a/src/read_dump.cpp b/src/read_dump.cpp
index c09bd38c87..71d302c4f1 100644
--- a/src/read_dump.cpp
+++ b/src/read_dump.cpp
@@ -233,7 +233,7 @@ void ReadDump::setup_reader(int narg, char **arg)
   // create Nreader reader classes per reader
   // match readerstyle to options in style_reader.h
 
-  if (0) {
+  if (false) {
     return;        // dummy line to enable else-if macro expansion
 
 #define READER_CLASS
@@ -289,7 +289,7 @@ bigint ReadDump::seek(bigint nrequest, int exact)
         readers[0]->open_file(multiname.c_str());
       } else readers[0]->open_file(files[ifile]);
 
-      while (1) {
+      while (true) {
         eofflag = readers[0]->read_time(ntimestep);
         if (eofflag) break;
         if (ntimestep >= nrequest) break;
@@ -333,7 +333,7 @@ bigint ReadDump::seek(bigint nrequest, int exact)
       readers[i]->open_file(multiname.c_str());
 
       bigint step;
-      while (1) {
+      while (true) {
         eofflag = readers[i]->read_time(step);
         if (eofflag) break;
         if (step == ntimestep) break;
@@ -382,7 +382,7 @@ bigint ReadDump::next(bigint ncurrent, bigint nlast, int nevery, int nskip)
         } else readers[0]->open_file(files[ifile]);
       }
 
-      while (1) {
+      while (true) {
         eofflag = readers[0]->read_time(ntimestep);
         if (eofflag) break;
         if (ntimestep > nlast) break;
@@ -435,7 +435,7 @@ bigint ReadDump::next(bigint ncurrent, bigint nlast, int nevery, int nskip)
       readers[i]->open_file(multiname.c_str());
 
       bigint step;
-      while (1) {
+      while (true) {
         eofflag = readers[i]->read_time(step);
         if (eofflag) break;
         if (step == ntimestep) break;
diff --git a/src/rerun.cpp b/src/rerun.cpp
index ce21fbc2b8..78b1a28cb6 100644
--- a/src/rerun.cpp
+++ b/src/rerun.cpp
@@ -156,7 +156,7 @@ void Rerun::command(int narg, char **arg)
   if (ntimestep < 0)
     error->all(FLERR,"Rerun dump file does not contain requested snapshot");
 
-  while (1) {
+  while (true) {
     ndump++;
     rd->header(firstflag);
     update->reset_timestep(ntimestep);
diff --git a/src/universe.cpp b/src/universe.cpp
index 005a91fc6b..bd06300d12 100644
--- a/src/universe.cpp
+++ b/src/universe.cpp
@@ -98,7 +98,7 @@ void Universe::reorder(char *style, char *arg)
       char *ptr;
       if (!fgets(line,MAXLINE,fp))
         error->one(FLERR,"Unexpected end of -reorder file");
-      while (1) {
+      while (true) {
         if ((ptr = strchr(line,'#'))) *ptr = '\0';
         if (strspn(line," \t\n\r") != strlen(line)) break;
         if (!fgets(line,MAXLINE,fp))
diff --git a/src/utils.cpp b/src/utils.cpp
index 507500f116..b6c0908934 100644
--- a/src/utils.cpp
+++ b/src/utils.cpp
@@ -957,7 +957,7 @@ std::vector<std::string> utils::split_words(const std::string &text)
     }
 
     // unquoted
-    while (1) {
+    while (true) {
       if ((c == '\'') || (c == '"')) goto quoted;
       // skip escaped quote
       if ((c == '\\') && ((buf[1] == '\'') || (buf[1] == '"'))) {
diff --git a/src/variable.cpp b/src/variable.cpp
index 22f792b5ec..0add581c48 100644
--- a/src/variable.cpp
+++ b/src/variable.cpp
@@ -692,7 +692,7 @@ int Variable::next(int narg, char **arg)
       if (!random) random = new RanMars(lmp,seed);
       int delay = (int) (1000000*random->uniform());
       platform::usleep(delay);
-      while (1) {
+      while (true) {
         if (!rename("tmp.lammps.variable","tmp.lammps.variable.lock")) break;
         delay = (int) (1000000*random->uniform());
         platform::usleep(delay);
@@ -1234,7 +1234,7 @@ double Variable::evaluate(char *str, Tree **tree, int ivar)
   if (str == nullptr)
     print_var_error(FLERR,"Invalid syntax in variable formula",ivar);
 
-  while (1) {
+  while (true) {
     onechar = str[i];
 
     // whitespace: just skip
@@ -3214,7 +3214,7 @@ int Variable::find_matching_paren(char *str, int i, char *&contents, int ivar)
 
   int istart = i;
   int ilevel = 0;
-  while (1) {
+  while (true) {
     i++;
     if (!str[i]) break;
     if (str[i] == '(') ilevel++;
@@ -4722,7 +4722,7 @@ double Variable::evaluate_boolean(char *str)
   int i = 0;
   int expect = ARG;
 
-  while (1) {
+  while (true) {
     onechar = str[i];
 
     // whitespace: just skip
@@ -5016,7 +5016,7 @@ int VarReader::read_scalar(char *str)
   // read one string from file
 
   if (me == 0) {
-    while (1) {
+    while (true) {
       ptr = fgets(str,MAXLINE,fp);
       if (!ptr) { n=0; break; }             // end of file
       ptr[strcspn(ptr,"#")] = '\0';         // strip comment
@@ -5059,7 +5059,7 @@ int VarReader::read_peratom()
 
   char str[MAXLINE];
   if (me == 0) {
-    while (1) {
+    while (true) {
       ptr = fgets(str,MAXLINE,fp);
       if (!ptr) { n=0; break; }             // end of file
       ptr[strcspn(ptr,"#")] = '\0';         // strip comment
diff --git a/src/write_coeff.cpp b/src/write_coeff.cpp
index 6f53a97e8f..a21a2634fc 100644
--- a/src/write_coeff.cpp
+++ b/src/write_coeff.cpp
@@ -92,7 +92,7 @@ void WriteCoeff::command(int narg, char **arg)
     fprintf(two,"# LAMMPS coeff file via write_coeff, version %s\n",
             lmp->version);
 
-    while (1) {
+    while (true) {
       int coeff_mode = REGULAR_MODE;
       if (fgets(str,256,one) == nullptr) break;
 
diff --git a/src/write_dump.cpp b/src/write_dump.cpp
index 89c976fe09..53ab80149a 100644
--- a/src/write_dump.cpp
+++ b/src/write_dump.cpp
@@ -57,7 +57,7 @@ void WriteDump::command(int narg, char **arg)
   for (int i = 2; i < modindex; ++i)
     dumpargs[i+2] = arg[i];
 
-  if (0) {
+  if (false) {
     return;         // dummy line to enable else-if macro expansion
 
 #define DUMP_CLASS
diff --git a/tools/binary2txt.cpp b/tools/binary2txt.cpp
index a7724ffbd2..dfa81e8a6e 100644
--- a/tools/binary2txt.cpp
+++ b/tools/binary2txt.cpp
@@ -97,7 +97,7 @@ int main(int narg, char **arg)
 
     // loop over snapshots in file
 
-    while (1) {
+    while (true) {
       int endian = 0x0001;
       int revision = 0x0001;
 
diff --git a/unittest/force-styles/test_config_reader.cpp b/unittest/force-styles/test_config_reader.cpp
index 945c16c649..65e9e4b0f6 100644
--- a/unittest/force-styles/test_config_reader.cpp
+++ b/unittest/force-styles/test_config_reader.cpp
@@ -83,7 +83,7 @@ void TestConfigReader::prerequisites(const yaml_event_t &event)
     std::stringstream data((char *)event.data.scalar.value);
     std::string key, value;
 
-    while (1) {
+    while (true) {
         data >> key >> value;
         if (data.eof()) break;
         config.prerequisites.emplace_back(key, value);
@@ -138,7 +138,7 @@ void TestConfigReader::extract(const yaml_event_t &event)
     std::stringstream data((char *)event.data.scalar.value);
     std::string name;
     int value;
-    while (1) {
+    while (true) {
         data >> name >> value;
         if (data.eof()) break;
         config.extract.emplace_back(name, value);