Pasted

#include <stdio.h>
 
enum boolean {True = 1, False = 0}; 
 
int sum (int, int);
int difference (int, int);
int multiplication (int, int);
 
int main(void) {
    
    int op, num1, num2;
    
    printf ("Choose your operation\n");
    printf ("1. Sum\n");
    printf ("2. Number distance (always positive)\n");
    printf ("3. Multiplication\n");
    
    scanf("%d", &op);
    
    printf("Insert first number: ");
    scanf("%d", &num1);
    printf("\n");
    
    printf("Insert second number: ");
    scanf("%d", &num2);
    printf("\n");
    
    switch(op) {
        case 1:
            printf("The sum of %d and %d is: %d", num1, num2, sum(num1, num2));
            break;
        case 2:
            printf("The distance between %d and %d is: %d", num1, num2, difference(num1, num2));
            break;
        case 3:
            printf("The multiplication of %d and %d is: %d", num1, num2, multiplication(num1, num2));
            break;
    }
    
    // your code goes here
    return 0;
}
 
int sum (int num1, int num2) {
    return num1 + num2;
}
 
enum boolean is_bigger (int num1, int num2) {
    return num1 > num2;
}
 
int difference (int num1, int num2) {
    if (is_bigger(num1, num2)) {
        return num1 - num2;
    } else {
        return num2 - num1;
    }
}
 
int multiplication (int num1, int num2) {
    if (num2 == 0) {
        return num1;
    } else {
        return multiplication (num1 + num1, num2 - 1);
    }
}