std::sub_sat - cppreference.com (original) (raw)

| | | | | --------------------------------------------------------------- | | ------------- | | template< class T > constexpr T sub_sat( T x, T y ) noexcept; | | (since C++26) |

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_, if _q_ is representable as a value of type T. Otherwise,
• the largest or smallest value of type T, whichever is closer to the _q_.

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

• 1 Parameters
• 2 Return value
• 3 Notes
• 4 Possible implementation
• 5 Example
• 6 See also
• 7 External links

[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.

[edit] Possible implementation

See libstdc++ (gcc).

[edit] Example

Can be previewed on Compiler Explorer

#include #include   static_assert ("" && (std::sub_sat(INT_MIN + 4, 3) == INT_MIN + 1) // not saturated && (std::sub_sat(INT_MIN + 4, 5) == INT_MIN) // saturated && (std::sub_sat(INT_MAX - 4, -3) == INT_MAX - 1) // not saturated && (std::sub_sat(INT_MAX - 4, -5) == INT_MAX) // saturated && (std::sub_sat(4, 3) == 1) // not saturated && (std::sub_sat(4, 5) == 0) // saturated );   int main() {}

[edit] See also

[edit] External links