NAME¶

std::gcd - std::gcd

Synopsis¶

Defined in header <numeric>
template< class M, class N > (since C++17)
constexpr std::common_type_t<M, N> gcd( M m, N n );

Computes the greatest common divisor of the integers m and n.

If either M or N is not an integer type, or if either is (possibly cv-qualified)
bool, the program is ill-formed.

If either |m| or |n| is not representable as a value of type std::common_type_t<M,
N>, the behavior is undefined.

Parameters¶

m, n - integer values

Return value¶

If both m and n are zero, returns zero. Otherwise, returns the greatest common
divisor of |m| and |n|.

Exceptions¶

Throws no exceptions.

Notes¶

Feature-test macro Value Std Feature
__cpp_lib_gcd_lcm 201606L (C++17) std::gcd, std::lcm

Example¶

// Run this code

#include <numeric>

int main()
{
constexpr int p{2 * 2 * 3};
constexpr int q{2 * 3 * 3};
static_assert(2 * 3 == std::gcd(p, q));

static_assert(std::gcd( 6, 10) == 2);
static_assert(std::gcd( 6, -10) == 2);
static_assert(std::gcd(-6, -10) == 2);

static_assert(std::gcd( 24, 0) == 24);
static_assert(std::gcd(-24, 0) == 24);
}

See also¶

lcm computes the least common multiple of two integers
(C++17) (function template)