#include <stdio.h>
#define FILENAME "mylife.txt"
int main() {
  int a, b, n;
  FILE *fp;
  printf("input integer a and b.\n");
  printf("a = ");
  scanf("%d", &a);
  printf("b = ");
  scanf("%d", &b);
  if ((fp = fopen(FILENAME, "wt")) != NULL) {
    printf("now writing to the file %s the value of a + b.\n", FILENAME);
    fprintf(fp, "%d\n", a + b);
    printf("finished.\n");
    fclose(fp);
  }
  if ((fp = fopen(FILENAME, "rt")) != NULL) {
    printf("now reading from the file %s the integer.\n", FILENAME);
    fscanf(fp, "%d", &n);
    printf("finished.\n");    
    printf("In the file '%s', the value '%d' has been written.\n", FILENAME, n);
    fclose(fp);
  }
  return 0;
}
/* end */

input integer a and b.
a = b =