std::gcd

 

C++

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gcd (C++17)	lcm (C++17)
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ckd_add (C++26) ckd_sub (C++26)	ckd_mul (C++26)

 

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

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(){constexprint p{2*2*3};constexprint 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 (C++17)

computes the least common multiple of two integers (function template)