std::mul_sat

Since C++26

Header: <numeric>

Computes the saturating multiplication x × y. This operation (unlike built-in arithmetic operations on integers) behaves as-if it is a mathematical operation with an infinite range. Let q denote the result of such operation. Returns:

# Declarations

template< class T >
constexpr T mul_sat( T x, T y ) noexcept;

(since C++26)

# Parameters

x, y: integer values

# Return value

Saturated x × y.

# Notes

Unlike the built-in arithmetic operators on integers, the integral promotion does not apply to the x and y arguments.

If two arguments of different type are passed, the call fails to compile, i.e. the behavior relative to template argument deduction is the same as for std::min or std::max.

Most modern hardware architectures have efficient support for saturation arithmetic on SIMD vectors, including SSE2 for x86 and NEON for ARM.

# Example

#include <climits>
#include <numeric>
 
static_assert
(""
    && (std::mul_sat<int>(2, 3) == 6) // not saturated
    && (std::mul_sat<int>(INT_MAX / 2, 3) == INT_MAX) // saturated
    && (std::mul_sat<int>(-2, 3) == -6) // not saturated
    && (std::mul_sat<int>(INT_MIN / -2, -3) == INT_MIN) // saturated
    && (std::mul_sat<unsigned>(2, 3) == 6) // not saturated
    && (std::mul_sat<unsigned>(UINT_MAX / 2, 3) == UINT_MAX) // saturated
);
 
int main() {}