std::lcm
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(C++17)
lcm
(C++17)
(C++20)
(C++20)
(C++17)
(C++17)
(C++17)
(C++17)
(C++17)
(C++17)
(C++26)
Defined in header
<numeric>
template< class M, class N >
constexpr std::common_type_t <M, N> lcm( M m, N n );
(since C++17)
constexpr std::common_type_t <M, N> lcm( M m, N n );
Computes the least common multiple 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.
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>.
[edit] Parameters
m, n
-
integer values
[edit] Return value
If either m or n is zero, returns zero. Otherwise, returns the least common multiple of |m| and |n|.
[edit] Exceptions
Throws no exceptions.
[edit] Notes
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_gcd_lcm |
201606L |
(C++17) | std::gcd , std::lcm
|
[edit] Example
Run this code
#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