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std::add_sat(3) C++ Standard Libary std::add_sat(3) NAME std::add_sat - std::add_sat Synopsis Defined in header <numeric> template< class T > (since C++26) constexpr T add_sat( T x, T y ) noexcept; Computes the saturating addition 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 in- teger type, or an unsigned version of such types. In particular, T must not be (possi- bly cv-qualified) bool, char, wchar_t, char8_t, char16_t, and char32_t, as these types are not intended for arithmetic. Parameters x, y - integer values Return value Saturated x + y. Exceptions Throws no exceptions. 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 satu- ration 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 arith- metic Possible implementation See libstdc++ (gcc). Example Can be previewed on Compiler Explorer. // Run this code #include <climits> #include <limits> #include <numeric> static_assert(CHAR_BIT == 8); static_assert(UCHAR_MAX == 255); int main() { constexpr int a = std::add_sat(3, 4); // no saturation occurs, T = int static_assert(a == 7); constexpr unsigned char b = std::add_sat<unsigned char>(UCHAR_MAX, 4); // saturated static_assert(b == UCHAR_MAX); constexpr unsigned char c = std::add_sat(UCHAR_MAX, 4); // not saturated, T = int // add_sat(int, int) returns int tmp == 259, // then assignment truncates 259 % 256 == 3 static_assert(c == 3); // unsigned char d = std::add_sat(252, c); // Error: inconsistent de- ductions for T constexpr unsigned char e = std::add_sat<unsigned char>(251, a); // saturated static_assert(e == UCHAR_MAX); // 251 is of type T = unsigned char, `a` is converted to un- signed char value; // might yield an int -> unsigned char conversion warning for `a` constexpr signed char f = std::add_sat<signed char>(-123, -3); // not saturated static_assert(f == -126); constexpr signed char g = std::add_sat<signed char>(-123, -13); // saturated static_assert(g == std::numeric_limits<signed char>::min()); // g == -128 } See also sub_sat saturating subtraction operation on two integers (C++26) (function template) mul_sat saturating multiplication operation on two integers (C++26) (function template) div_sat saturating division operation on two integers (C++26) (function template) saturate_cast returns an integer value clamped to the range of a an- other integer (C++26) type (function template) clamp clamps a value between a pair of boundary values (C++17) (function template) in_range checks if an integer value is in the range of a given integer type (C++20) (function template) min returns the smallest finite value of the given type [static] (public static member function of std::numeric_lim- its<T>) max returns the largest finite value of the given type [static] (public static member function of std::numeric_lim- its<T>) External links 1. A branch-free implementation of saturation arithmetic Lockless- inc.com, 2012 http://cppreference.com 2024.06.10 std::add_sat(3)
NAME | Synopsis | Parameters | Return value | Exceptions | Notes | Possible implementation | Example | See also | External links
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