C open read write file《转载》

#include <stdio.h>
#include <stdlib.h>

double d[10] = {
  1.3, 1.7, 1.23, 1.9, 0.97,
  1.5, 7.4, 0.0, 1.01, 8.75
};

int main(void)
{
  int i;
  FILE *fp;

  if((fp = fopen("my.txt", "wb")) == NULL) {
    printf("Cannot open file.\n");
    exit(1);
  }

  /* write the entire array in one step */
  if( fwrite(d, sizeof d, 1, fp) != 1) {
    printf("Write error.\n");
    exit(1);
  }
  fclose(fp);

  if((fp = fopen("my.txt", "rb"))==NULL) {
    printf("Cannot open file.\n");
    exit(1);
  }

  /* clear the array */
  for(i = 0; i < 10; i++)
      d[i] = 0.0;

  /* read the entire array in one step */
  if(fread(d, sizeof d, 1, fp) != 1) {
    printf("Read error.\n");
    exit(1);
  }
  fclose(fp);

  /* display the array */
  for(i = 0; i < 10; i++)
      printf("%f ", d[i]);

  return 0;
}