Question

Array/File Functions
Write a function to accept three arguments:
 The name of a file, a pointer to an int array, and the size of the array. The
function should open the specified file in binary mode, write the contents of the
array to the file, and then close the file.
Write another function to accept three arguments:
 The name of a file, a pointer to an int array, and the size of the array. The
function should open the specified file in binary mode, read its contents into the
array, and then close the file.
Write a complete program that demonstrates these functions:
 Function to write an array to a file, and then read the data from the same file.
An array values shall be created, write to a file, and after that data are read from
the file, and display the array’s contents on the screen.

Notes:
 The filename parameter is the name of the file,
 The array parameter is a pointer to the array, and
 The size parameter is the number of elements in the array (size of the array)

Answer 1

#define _CRT_SECURE_NO_WARNINGS

#include <stdio.h>

#include<stdlib.h>

//function to write the array to a file in binary mode

void binaryWrite(char *fname, int *ptr, int size);

//function to read from file into the array

void binaryRead(char *fname, int *ptr, int size);

int main(void) {

  //declare an array and initialize with some elements

  int arr[] = { 1,2,3,4,5,6 };

//using different array retArray while reading from bianry file , jsut to show that we are getting actutal result from the binary file

  int *retArray=(int*)malloc(sizeof(sizeof(arr) / sizeof(int)));

  int i;

printf("Content of array to write in binary mode to a file: \n");

for (i = 0; i < sizeof(arr) / sizeof(int); i++)

  {

    printf("%d ", arr[i]);

  }

printf("\n");

  binaryWrite("binaryWrite.dat", arr, sizeof(arr) / sizeof(int));

  binaryRead("binaryWrite.dat", retArray, sizeof(arr) / sizeof(int));

  //print read array

  printf("Array after reading binary file\n");

  binaryWrite("binaryWrite.dat", arr, sizeof(arr) / sizeof(int));

  for (i = 0; i < sizeof(arr) / sizeof(int); i++)

  {

    printf("%d ", retArray[i]);

  }

printf("\n");

  return 0;

}

//function to write the array to a file in binary mode

void binaryWrite(char *fname, int *ptr, int size)

{

  //open file in binary mode

  FILE *fp;

  fp = fopen(fname, "wb");

  if (fp == NULL)

  {

    printf("Not able to open file %s for writing in binary mode\n", fname);

    return;

  }

  fwrite(ptr, sizeof(int), size, fp);

  fclose(fp);

}

//function to read from file into the array

void binaryRead(char *fname, int *ptr, int size)

{

  //open file in binary mode

  FILE *fp;

  fp = fopen(fname, "rb");

  if (fp == NULL)

  {

    printf("Not able to open file %s for reading in binary mode\n", fname);

    return;

  }

  fread(ptr, sizeof(int), size, fp);

  fclose(fp);

}

/*Output

 ./main

Content of array to write in binary mode to a file:

1 2 3 4 5 6

Array after reading binary file

1 2 3 4 5 6

*/

//Since programming language is not given , I am taking it as C , you can also execute this code in C++