std::make_signed
Defined in header <type_traits> | | |
|---|---|---|
template< class T > struct make_signed; | | (since C++11) |
如果T是除bool%29或枚举类型外的整数%28，则提供成员类型type的整数类型。T，使用相同的cv-限定符。
否则，行为就没有定义。
成员类型
Name | Definition |
|---|---|
type | the signed integer type corresponding to T |
帮助者类型
template< class T > using make_signed_t = typename make_signed<T>::type; | | (since C++14) |
|---|
例
二次
#include <iostream>
#include <type_traits>
int main() {
typedef std::make_signed<char>::type char_type;
typedef std::make_signed<int>::type int_type;
typedef std::make_signed<volatile long>::type long_type;
bool ok1 = std::is_same<char_type, signed char>::value;
bool ok2 = std::is_same<int_type, signed int>::value;
bool ok3 = std::is_same<long_type, volatile signed long>::value;
std::cout << std::boolalpha
<< "char_type is 'signed char'? : " << ok1 << '\n'
<< "int_type is 'signed int'? : " << ok2 << '\n'
<< "long_type is 'volatile signed long'? : " << ok3 << '\n';
}二次
产出：
二次
char_type is 'signed char'? : true
int_type is 'signed int'? : true
long_type is 'volatile signed long'? : true二次
另见
is_signed (C++11) | checks if a type is signed arithmetic type (class template) |
|---|---|
is_unsigned (C++11) | checks if a type is unsigned arithmetic type (class template) |
make_unsigned (C++11) | makes the given integral type unsigned (class template) |
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