std::sub_sat
<numeric>
constexpr T sub_sat( T x, T y ) noexcept;
Computes the saturating subtraction 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:
-
q, ifqis representable as a value of typeT. Otherwise, - the largest or smallest value of type
T, whichever is closer to theq.
This overload participates in overload resolution only if T is an integer type, that is: signed char, short, int, long, long long, an extended signed integer type, or an unsigned version of such types. In particular, T must not be (possibly cv-qualified) bool, char, wchar_t, char8_t, char16_t, and char32_t, as these types are not intended for arithmetic.
Contents
[edit] Parameters
[edit] Return value
Saturated x - y.
[edit] 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.
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_saturation_arithmetic |
202311L |
(C++26) | Saturation arithmetic |
[edit] Possible implementation
See libstdc++ (gcc).
[edit] Example
Can be previewed on Compiler Explorer
#include <climits> #include <numeric> static_assert ("" && (std::sub_sat<int>(INT_MIN + 4, 3) == INT_MIN + 1) // not saturated && (std::sub_sat<int>(INT_MIN + 4, 5) == INT_MIN ) // saturated && (std::sub_sat<int>(INT_MAX - 4, -3) == INT_MAX - 1) // not saturated && (std::sub_sat<int>(INT_MAX - 4, -5) == INT_MAX ) // saturated && (std::sub_sat<unsigned>(4, 3) == 1) // not saturated && (std::sub_sat<unsigned>(4, 5) == 0) // saturated ); int main() {}
[edit] See also
(function template) [edit]
(function template) [edit]
(public static member function of
std::numeric_limits<T>) [edit]
(public static member function of
std::numeric_limits<T>) [edit]