replacewithsum.c

// 2 numbers - a & b, are written in a file. Write a program to replace them with their sum.

#include<stdio.h>

int main(){
    FILE *fptr;
    fptr = fopen("sum.txt", "r");   

    int a;
    fscanf(fptr, "%d", &a);
    int b;
    fscanf(fptr, "%d", &b);

    fclose(fptr);

    fptr = fopen("sum.txt", "w");   
    fprintf(fptr, "%d", a+b);
    fclose(fptr);

    return 0;
}