C/File/File fprintf fscanf

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fprintf demo

#include <stdio.h>
#include <stdlib.h>
int main() {
    int value;
    value = 1;
    if (value < 0)
        fprintf(stderr, "Fatal Error:Abort\n");
    exit(8);
    printf("We did not die\n");
    return (0);
}


Use fprintf and fscanf to save and read file

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(int argc, char *argv[])
{
  FILE *fp;
  double ld;
  int d;
  char str[80];
  if(argc!=2) {
    printf("Specify file name.\n");
    exit(1);
  }
  /* open file for output */
  if((fp = fopen(argv[1], "w"))==NULL) {
    printf("Cannot open file.\n");
    exit(1);
  }
  fprintf(fp, "%f %d %s", 345.342, 908, "hiiiiiiii");
  fclose(fp);
  /* open file for input */
  if((fp = fopen(argv[1], "r"))==NULL) {
    printf("Cannot open file.\n");
    exit(1);
  }
  fscanf(fp, "%lf%d%s", &ld, &d, str);
  printf("%f %d %s", ld, d, str);
  fclose(fp);
  return 0;
}