Question

I have the following code:

int checkCorrectness(int i,char *iStr)
{
   if(atoi(iStr) == i)
     return 1;
   return 0;
}
void foo(int i)
{
    printf("inside foo %d\n",i);
}
void print()
{
    char mystring[100];
    freopen("myfile.txt","w+",stdout);
    for(int i =0;i < 100;++i)
    {
      foo(i);
      FILE *f = fopen("myfile.txt","r");
      if (f == NULL) perror ("Error opening file");
      else {
         while ( fgets (mystring , 100 , f) != NULL );
         if(!checkCorrectness(i,mystring);
            break;
         fclose (f);

      }
     }
    fclose(stdout);
}

Is this code save?I mean is it OK to call fopen after freopen was called and its stream was not closed? Thank you

Answer 1

Your code looks safe. You are allowed to open the same file more than once in a process. The file descriptors will not interract.

I’d steer away from reopening stdout like you do. You could do this entire program with a single fopen and avoid the mess you’re creating: look up fprintf!