How to use index in the file name

Question

This is probably trivial question. I am not a professional programmer, I am rather a mathematician who is doing some numerical experiment using C. I would like the output of my

Answer 1

You could try this:

#include 
#include 

int main(void) {

   int i = 0;
   for (i = 0; i < 10; i++) {
      char filename[64];
      sprintf(filename, "file%d", i);    
      FILE *fp = fopen(filename, "w");
      fprintf(fp, "%d\n", i);
      fclose(fp);
   }
   return 0;
}

Your code is almost ok. Some observations:

• Use sprintf to create the name of the file. In C there is not a concatenate operator of strings.
• You don't need to create an array of file pointers.
• And of course, this may be improved: handling the size of the filename, padding the numbers, etc.