From d572d8f051bc1e596cb3154b17a2eed4a8e8c95a Mon Sep 17 00:00:00 2001
From: Axel Kohlmeyer <akohlmey@gmail.com>
Date: Sat, 7 Jan 2023 15:47:46 -0500
Subject: [PATCH] avoid sprintf() through C++ features and libfmt

---
 src/read_data.cpp |  8 ++++----
 src/read_data.h   |  2 +-
 src/variable.cpp  | 17 +++++------------
 3 files changed, 10 insertions(+), 17 deletions(-)

diff --git a/src/read_data.cpp b/src/read_data.cpp
index 85f5accc4b..414e9ff4a2 100644
--- a/src/read_data.cpp
+++ b/src/read_data.cpp
@@ -2437,13 +2437,13 @@ void ReadData::parse_coeffs(char *line, const char *addstr, int dupflag, int nof
   if (noffset) {
     int value = utils::inumeric(FLERR, coeffarg[0], false, lmp);
     if (labelmode) value = ilabel[value - 1];
-    sprintf(argoffset1, "%d", value + offset);
-    coeffarg[0] = argoffset1;
+    argoffset1 = std::to_string(value + offset);
+    coeffarg[0] = (char *)argoffset1.c_str();
     if (noffset == 2) {
       value = utils::inumeric(FLERR, coeffarg[1], false, lmp);
       if (labelmode) value = ilabel[value - 1];
-      sprintf(argoffset2, "%d", value + offset);
-      coeffarg[1] = argoffset2;
+      argoffset2 = std::to_string(value + offset);
+      coeffarg[1] = (char *)argoffset2.c_str();
     }
   }
 }
diff --git a/src/read_data.h b/src/read_data.h
index c630c027bc..e97f225997 100644
--- a/src/read_data.h
+++ b/src/read_data.h
@@ -37,7 +37,7 @@ class ReadData : public Command {
   FILE *fp;
   char **coeffarg;
   int ncoeffarg, maxcoeffarg;
-  char argoffset1[8], argoffset2[8];
+  std::string argoffset1, argoffset2;
 
   bigint id_offset, mol_offset;
 
diff --git a/src/variable.cpp b/src/variable.cpp
index c07e62648b..65a1f7d885 100644
--- a/src/variable.cpp
+++ b/src/variable.cpp
@@ -266,11 +266,8 @@ void Variable::set(int narg, char **arg)
       num[nvar] = utils::inumeric(FLERR,arg[2],false,lmp);
       data[nvar] = new char*[1];
       data[nvar][0] = nullptr;
-      if (narg == 4) {
-        char digits[12];
-        sprintf(digits,"%d",num[nvar]);
-        pad[nvar] = strlen(digits);
-      } else pad[nvar] = 0;
+      if (narg == 4) pad[nvar] = std::to_string(num[nvar]).size();
+      else pad[nvar] = 0;
     }
 
     if (num[nvar] < universe->nworlds)
@@ -955,13 +952,9 @@ char *Variable::retrieve(const char *name)
       style[ivar] == SCALARFILE) {
     str = data[ivar][which[ivar]];
   } else if (style[ivar] == LOOP || style[ivar] == ULOOP) {
-    char result[16];
-    if (pad[ivar] == 0) sprintf(result,"%d",which[ivar]+1);
-    else {
-      char padstr[16];
-      sprintf(padstr,"%%0%dd",pad[ivar]);
-      sprintf(result,padstr,which[ivar]+1);
-    }
+    std::string result;
+    if (pad[ivar] == 0) result = std::to_string(which[ivar]+1);
+    else result = fmt::format("{:0>{}d}",which[ivar]+1, pad[ivar]);
     delete[] data[ivar][0];
     str = data[ivar][0] = utils::strdup(result);
   } else if (style[ivar] == EQUAL) {