Safe Integer Multiplication in C

Question

Write a C function that takes two integers as input and safely multiplies them together. If the multiplication would result in an overflow, your function should return false; otherwise, it should store the result and return true.

Answer 1

#include <stdbool.h>

bool safeMultiply(int a, int b, int *result) {

int x = a * b;

if (a != 0 && x / a != b) {

return false; // overflow detected

}

*result = x;

return true;

}

This function checks whether an overflow would occur when multiplying a and b by performing the multiplication and then dividing the result by a. If this division does not yield b, then an overflow occurred during the multiplication.