How to binary search on .txt file using recursion in C?

I want to solve a c program problem. I want to Binary search using recursion, Input taken from file and result also to be written in that file too. How to solve below problem?

#include <stdio.h>
int binaryScr(int a[], int low, int high, int m)
{
    if (high >= low)
    {
        int mid = low + (high - low) / 2;
        if (a[mid] == m)
            return mid;
        if(a[mid] > m)
            return binaryScr(a, low, mid - 1, m);
        return binaryScr(a, mid + 1, high, m);
    }
    return -1;
}
int main(void)
{
    int a[] = { 12, 13, 21, 36, 40 };
    int i,m;
    for(i=0; i<5; i++)
    {
        printf("%d ",a[i]);
    }
    printf("\n");
    int n = sizeof(a) / sizeof(a[0]);
    printf("Enter the number to be searched: ");
    scanf("%d", &m);
    int result = binaryScr(a, 0, n - 1, m);
    if (result == -1)
    printf("The element is not present in array");
    else
    printf("The element is present at index %d", result);
    return 0;
}