Why Doesn't C Throw Exceptions for Integer Division by Zero, and How Can We Handle It?

Catching Run-Time Division by Zero Exception

Problem Statement

In the given code snippet, division by zero does not trigger an exception. Why is this the case and how can we ensure exceptions are thrown for such errors?

Explanation

Unlike other common runtime errors, integer division by zero is not an exception in standard C . Floating-point division or remainder operations also do not inherently throw exceptions. Instead, these operations have undefined behavior when the second operand is zero. This means that the system could potentially behave unpredictably, including throwing exceptions, crashing the program, or even performing actions outside the scope of the program.

Throwing Custom Exceptions

Since standard C does not handle division by zero as an exception, developers must manually check for such conditions and throw custom exceptions if necessary. For instance, one could throw an overflow_error or a domain_error to indicate a divide by zero error.

Code Example

The following modified code snippet demonstrates how to catch division by zero exceptions using a custom intDivEx function:

#include <iostream>
#include <stdexcept>

// Integer division, catching divide by zero.
inline int intDivEx(int numerator, int denominator) {
    if (denominator == 0)
        throw std::overflow_error("Divide by zero exception");
    return numerator / denominator;
}

int main() {
    int i = 42;

    try {
        i = intDivEx(10, 0);
    } catch (std::overflow_error &e) {
        std::cout  "  " <h3 id="Output">Output:</h3>
<pre class="brush:php;toolbar:false">Divide by zero exception -> 42
5

This code correctly throws and catches the division by zero exception, preserving the original value of i.

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