use const char * instead of char * so we don't need a cast for string constants

src/PYTHON/python_impl.cpp

@@ -359,7 +359,7 @@ void PythonImpl::invoke_function(int ifunc, char *result)
 
 /* ------------------------------------------------------------------ */
 
-int PythonImpl::find(char *name)
+int PythonImpl::find(const char *name)
 {
   for (int i = 0; i < nfunc; i++)
     if (strcmp(name,pfuncs[i].name) == 0) return i;
@@ -368,7 +368,8 @@ int PythonImpl::find(char *name)
 
 /* ------------------------------------------------------------------ */
 
-int PythonImpl::variable_match(char *name, char *varname, int numeric)
+int PythonImpl::variable_match(const char *name, const char *varname,
+                               int numeric)
 {
   int ifunc = find(name);
   if (ifunc < 0) return -1;

src/PYTHON/python_impl.h

@@ -27,8 +27,8 @@ class PythonImpl : protected Pointers, public PythonInterface {
   ~PythonImpl();
   void command(int, char **);
   void invoke_function(int, char *);
-  int find(char *);
-  int variable_match(char *, char *, int);
+  int find(const char *);
+  int variable_match(const char *, const char *, int);
   char *long_string(int);
   int execute_string(char *);
   int execute_file(char *);

src/lmppython.cpp

@@ -80,7 +80,7 @@ void Python::invoke_function(int ifunc, char *result)
 
 /* ------------------------------------------------------------------ */
 
-int Python::find(char *name)
+int Python::find(const char *name)
 {
   init();
   return impl->find(name);
@@ -88,7 +88,7 @@ int Python::find(char *name)
 
 /* ------------------------------------------------------------------ */
 
-int Python::variable_match(char *name, char *varname, int numeric)
+int Python::variable_match(const char *name, const char *varname, int numeric)
 {
   init();
   return impl->variable_match(name, varname, numeric);

src/lmppython.h

@@ -23,9 +23,9 @@ public:
   virtual ~PythonInterface();
   virtual void command(int, char **) = 0;
   virtual void invoke_function(int, char *) = 0;
-  virtual int find(char *) = 0;
-  virtual int variable_match(char *, char *, int) = 0;
-  virtual char * long_string(int ifunc) = 0;
+  virtual int find(const char *) = 0;
+  virtual int variable_match(const char *, const char *, int) = 0;
+  virtual char *long_string(int ifunc) = 0;
   virtual int execute_string(char *) = 0;
   virtual int execute_file(char *) = 0;
   virtual bool has_minimum_version(int major, int minor) = 0;
@@ -38,8 +38,8 @@ public:
 
   void command(int, char **);
   void invoke_function(int, char *);
-  int find(char *);
-  int variable_match(char *, char *, int);
+  int find(const char *);
+  int variable_match(const char *, const char *, int);
   char * long_string(int ifunc);
   int execute_string(char *);
   int execute_file(char *);

src/variable.cpp

@@ -752,9 +752,9 @@ int Variable::next(int narg, char **arg)
    return index or -1 if not found
 ------------------------------------------------------------------------- */
 
-int Variable::find(char *name)
+int Variable::find(const char *name)
 {
-  if(name==NULL) return -1;
+  if (name == nullptr) return -1;
   for (int i = 0; i < nvar; i++)
     if (strcmp(name,names[i]) == 0) return i;
   return -1;
@@ -864,7 +864,7 @@ int Variable::internalstyle(int ivar)
      caller must respond
 ------------------------------------------------------------------------- */
 
-char *Variable::retrieve(char *name)
+char *Variable::retrieve(const char *name)
 {
   int ivar = find(name);
   if (ivar < 0) return NULL;

src/variable.h

@@ -29,7 +29,7 @@ class Variable : protected Pointers {
   int set_string(char *, char *);
   int next(int, char **);
 
-  int find(char *);
+  int find(const char *);
   void set_arrays(int);
   void python_command(int, char **);
 
@@ -39,7 +39,7 @@ class Variable : protected Pointers {
   char *pythonstyle(char *, char *);
   int internalstyle(int);
 
-  char *retrieve(char *);
+  char *retrieve(const char *);
   double compute_equal(int);
   double compute_equal(char *);
   void compute_atom(int, int, double *, int, int);