Question

How to fix this? Why the compiler claims of it if I am using the variable in another code parts?

void replace(char ** src, const char s, const char replace) {
   while(*(*src) != '\0') {
      if(* (*src) == s) {
         news[size] = replace;
      } else {
         news[size] = *(*src);
      }
      *(*src) ++; // the error line 
      size++;
   }
   *src = news;
}

Answer 1

When you do *(*src)++ you’re basically dereferencing src, then doing a postfix increment on the pointer, then dereferencing the pointer. It’s a bug. You’re not using the final value, which is why the compiler warns you.

What you really want is (**src)++; i.e. dereference twice and then increment.