Fread( ) and fwrite( ) can read and write any type of information. - C File

C examples for File:File Operation

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Introduction

The following program writes and then reads back a double, an int, and a long to and from a disk file.

It uses sizeof to determine the length of each data type.

Demo Code

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

int main(void) {
   FILE *fp;//from w w w.  j  av a2s  .  c  o m
   double d = 12.23;
   int i = 101;
   long l = 123023L;

   if ((fp = fopen("test", "wb+")) == NULL) {
      printf("Cannot open file.\n");
      exit(1);
   }
   fwrite(&d, sizeof(double), 1, fp);
   fwrite(&i, sizeof(int), 1, fp);
   fwrite(&l, sizeof(long), 1, fp);

   rewind(fp);

   fread(&d, sizeof(double), 1, fp);
   fread(&i, sizeof(int), 1, fp);
   fread(&l, sizeof(long), 1, fp);

   printf("%f %d %ld", d, i, 1);

   fclose(fp);

   return 0;
}

Result


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