tel_num.c

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

#define CLEAR(x) memset(x, '\0', 512)
#define FILENAME "num.txt"

int main()
{
  FILE *fp;
  long int num = 3334590234L;
  long int num1 = 0L;


  if ( ( fp = fopen(FILENAME, "w+") ) == NULL )
    {
      perror("ERROR in reading file!\n");
      exit(-1);
    }
  else
    fprintf(fp,"%ld", num);

  fseek(fp, 0, SEEK_SET);

  fscanf(fp, "%ld",&num1);


  printf("ORIGINAL TELEPHON NUMBER : %ld\n", num);
  printf("READ TELEPHON NUMBER : %ld\n", num1);

  return EXIT_SUCCESS;


}