Defined in header <numeric> | ||
---|---|---|
template< class M, class N > constexpr std::common_type_t<M, N> lcm( M m, N n ); | (since C++17) |
Computes the least common multiple of the integers m
and n
.
m, n | - | integer values |
If either m
or n
is zero, returns zero. Otherwise, returns the least common multiple of |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.
The behavior is undefined if |m|
, |n|
, or the least common multiple of |m|
and |n|
is not representable as a value of type std::common_type_t<M, N>
.
Throws no exceptions.
Feature-test macro | Value | Std | Comment |
---|---|---|---|
__cpp_lib_gcd_lcm | 201606L | (C++17) |
std::gcd , std::lcm |
#include <iostream> #include <numeric> #define OUT(...) std::cout << #__VA_ARGS__ << " = " << __VA_ARGS__ << '\n' constexpr auto lcm(auto x, auto... xs) { return ((x = std::lcm(x, xs)), ...); } int main() { constexpr int p{2 * 2 * 3}; constexpr int q{2 * 3 * 3}; static_assert(2 * 2 * 3 * 3 == std::lcm(p, q)); static_assert(225 == std::lcm(45, 75)); static_assert(std::lcm( 6, 10) == 30); static_assert(std::lcm( 6, -10) == 30); static_assert(std::lcm(-6, -10) == 30); static_assert(std::lcm( 24, 0) == 0); static_assert(std::lcm(-24, 0) == 0); OUT(lcm(2*3, 3*4, 4*5)); OUT(lcm(2*3*4, 3*4*5, 4*5*6)); OUT(lcm(2*3*4, 3*4*5, 4*5*6, 5*6*7)); }
Output:
lcm(2*3, 3*4, 4*5) = 60 lcm(2*3*4, 3*4*5, 4*5*6) = 120 lcm(2*3*4, 3*4*5, 4*5*6, 5*6*7) = 840
(C++17) | constexpr function template returning the greatest common divisor of two integers (function template) |
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