Another #define example

Comments and questions to John Rowe.

Here is one solution using #define which demonstrates that it can be used for text strings as well as mathematical constants. The changes are shown highlighted.

#include <stdlib.h>
#include <stdio.h>
#define HSFILE "highscore.txt"
//
// Read the high score from a file, returning zero
// if the file does not exist.
int readhighscore() {
  int hs;
  FILE *infile;

  infile = fopen(HSFILE, "r");
  if ( infile == NULL ) // First time game has been played
    return 0;

  fscanf(infile, "%d", &hs);

  fclose(infile);

  return hs;
}

//
// Write the high score file checking that this game's
// high score is greater than the saved one.
void writehighscore(int hs) {
  FILE *outfile;
  
  if ( hs <= readhighscore())
    return;

  outfile = fopen(HSFILE, "w");
  if ( outfile == NULL ) {
    fprintf(stderr, "Cannot write high-score file\n");
    exit(1);
  } 

  fprintf(outfile, "%d", hs);

  fclose(outfile); 
}

int main() {
  int highscore;

  highscore = readhighscore(); 
  printf("High score: %d\n", highscore);

  writehighscore(12);
  highscore = readhighscore();
  printf("High score: %d\n", highscore);
  
  writehighscore(2); // Will do nothing
  return 0;
}

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