std::signed_integral

 

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核心语言概念 same_as (C++20) derived_from (C++20) convertible_to (C++20) common_reference_with (C++20) common_with (C++20) integral (C++20) signed_integral (C++20) unsigned_integral (C++20) floating_point (C++20) swappableswappable_with (C++20)(C++20) destructible (C++20) constructible_from (C++20) default_initializable (C++20)   move_constructible (C++20) copy_constructible (C++20) assignable_from (C++20)

比较概念 equality_comparableequality_comparable_with (C++20)(C++20) totally_orderedtotally_ordered_with (C++20)(C++20) 对象概念 movable (C++20) copyable (C++20) semiregular (C++20) regular (C++20) 可调用概念 invocableregular_invocable (C++20)(C++20) predicate (C++20) relation (C++20) equivalence_relation (C++20) strict_weak_order (C++20)

仅用于阐释的概念 boolean-testable  (C++20)

 

在标头 <concepts> 定义
template<class T > concept signed_integral =std::integral<T>&&std::is_signed_v<T>;		(C++20 起)

概念 signed_integral<T> 当且仅当 T 为整数类型且 std::is_signed_v<T> 为 true 时得到满足。

注解

signed_integral<T> 可以不为有符号整数类型，例如 char 类型（在 char 为有符号的系统上）。

示例

运行此代码

#include <concepts>#include <iostream>#include <string_view>   void test(std::signed_integralauto x, std::string_view text =""){std::cout<< text <<" ("+(text =="")<< x <<") is a signed integral\n";}   void test(std::unsigned_integralauto x, std::string_view text =""){std::cout<< text <<" ("+(text =="")<< x <<") is an unsigned integral\n";}   void test(auto x, std::string_view text =""){std::cout<< text <<" ("+(text =="")<< x <<") is non-integral\n";}   int main(){ test(42);// signed test(0xFULL, "0xFULL");// unsigned test('A');// platform-dependent test(true, "true");// unsigned test(4e-2, "4e-2");// non-integral (hex-float) test("∫∫");// non-integral}

可能的输出：

(42) is a signed integral 0xFULL (15) is an unsigned integral (A) is a signed integral true (1) is an unsigned integral 4e-2 (0.04) is non-integral (∫∫) is non-integral

引用

• C++23 标准（ISO/IEC 14882:2024）：

• 18.4.7 Arithmetic concepts [concepts.arithmetic]

• C++20 标准（ISO/IEC 14882:2020）：

• 18.4.7 Arithmetic concepts [concepts.arithmetic]

参阅

is_integral (C++11)	检查类型是否为整数类型 (类模板)
is_signed (C++11)	检查类型是否为有符号算术类型 (类模板)