An example of exception in C and Java

Example.c

#include <stdio.h>

// int add (int a, int b) {
//     return a + b;
// }

/*
 * @param {int} sum
 * @param {int} a
 * @param {int} b
 * @return {int} 0      success
 *               -1     null pointer
 *               -2     overflow
 *               -3     underflow
 */
int add (int * sum, int a, int b) {
    if (sum == NULL) return -1;     // Null Pointer
    *sum = a + b;

    if (a > 0 && b > 0 && *sum <= 0) return -2;     // Overflow
    if (a < 0 && b < 0 && *sum >= 0) return -3;     // Underflow

    return 0;   // success
}

int main () {
    int sum, a = -2147483648, b = -1;

    int ret = add(&sum, a, b);   // Underflow
    if (ret == 0) {
        printf("sum = %d\n", sum);
    } else {
        // error handle
        switch (ret) {
            case -1:
                printf("sum should not be NULL\n");
                break;

            case -2:
                printf("Overflow: %d, %d\n", a, b);
                break;

            case -3:
                printf("Underflow: %d, %d\n", a, b);    // "Underflow: -2147483648, -1"
                break;

            default:
                printf("Unknown Error Code: %d\n", ret);
        }
    }
}

Example.java

public class Example {
    // static int add (int a, int b) {
    //     return a + b;
    // }

    static int add (int a, int b) {
        int sum = a + b;

        // Overflow
        if (a > 0 && b > 0 && sum <= 0) {
            throw new RuntimeException("Overflow: " + a + ", " + b);
        }

        // Underflow
        if (a < 0 && b < 0 && sum >= 0) {
            throw new RuntimeException("Underflow: " + a + ", " + b);
        }

        return a + b;
    }

    public static void main(String [] args) {
        try {
            int result = add(Integer.MAX_VALUE, 1); // Overflow
            System.out.println(result);
        } catch (Exception e) {
            System.out.println(e.getMessage());     // "Overflow: 2147483647, 1"
        }
    }
}