Solution 1

#include <stdio.h>
int main()
{
    int arr[50], var, x, p, num, m;
    printf("Enter the position : ");
    scanf("%d", &p);
    printf("Enter the number : ");
    scanf("%d", &x);
    FILE *fp, *fpw;
    fp = fopen("F:\\inputr.txt", "r");
    fpw = fopen("F:\\outputr.txt", "w");
    int i = 0, j = 0;
    while(fscanf(fp,"%d",&arr[i])!=EOF)
    {
        i++;
    }
    for(j=i; j>=p-1; j--)
    {
        arr[j]=arr[j-1];
    }
    arr[p-1]=x;
    for(j=0; j<=i; j++)
    {
        num = arr[j];
        while(num != 0)
        {
            m = num % 10;
            num = num / 10;
        }
        fprintf(fpw, "%d ", m);
    }
    fclose(fp);
    fclose(fpw);
    return 0;
}