CODEWITHSUNDEEP
c++exceptiongreatest-common-divisorlcm
Álvaro
Álvaro

Reputation: 141

Unexpected Floating point excepction - c++

This program is supposed to compute the smallest common multiple. It does not present divisions by zero, nor weird operations (as far as I know), yet it breaks at some point. The program seems to return "Floating point exception (core dumped)" for any pair of values. *Precondition: a >= 1 and b >= 1. The code:

int mcd(int x, int y) { //computes greatest common divisor
    if (x == 0) return y;
    return mcd(y, x % y);
}

int mcm(int x, int y) { //computes smallest common multiple
    return x * y / mcd(x, y);
}

int main() {
    int a, b;
    int counter = 0;
    while (cin >> a >> b) {
        ++counter;
        cout << "#" << counter
        << " : " << mcm(a, b) << endl;
    }
}

What is causing this behaviour?

Upvotes: 1

Views: 84

Answers (1)

Mauro Castanho
Mauro Castanho

Reputation: 51

You are dividing by zero because your stop condition in line 2 is wrong. The right one is:

if (y == 0) return x;

Source: Euclidean Algorithm

Upvotes: 3

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