std::numeric_limits<T>::is_signed
From cppreference.com
< cpp | types | numeric limits
static const bool is_signed; |
(until C++11) | |
| static constexpr bool is_signed; |
(since C++11) | |
The value of std::numeric_limits<T>::is_signed is true for all signed arithmetic types T and false for the unsigned types. This constant is meaningful for all specializations.
[edit] Standard specializations
T
|
value of std::numeric_limits<T>::is_signed |
| /* non-specialized */ | false |
| bool | false |
| char | implementation-defined |
| signed char | true |
| unsigned char | false |
| wchar_t | implementation-defined |
| char8_t (since C++20) | false |
| char16_t (since C++11) | false |
| char32_t (since C++11) | false |
| short | true |
| unsigned short | false |
| int | true |
| unsigned int | false |
| long | true |
| unsigned long | false |
| long long (since C++11) | true |
| unsigned long long (since C++11) | false |
| float | true |
| double | true |
| long double | true |
[edit] Example
Run this code
#include <iostream> #include <iomanip> #include <limits> template<typename T> struct test { test(const char* name, int w = 15) { std::cout << std::left << std::setw(w) << (std::numeric_limits<T>::is_specialized ? name : "non-specialized") << " : " << (std::numeric_limits<T>::is_signed ? "" : "un") << "signed\n"; } }; int main() { test<bool>{"bool"}; test<char>{"char"}; test<wchar_t>{"wchar_t"}; test<char16_t>{"char16_t"}; test<char32_t>{"char32_t"}; test<float>{"float"}; struct delusion{}; test<delusion>{"delusion"}; test<decltype(42)>{"decltype(42)"}; }
Possible output:
bool : unsigned char : signed wchar_t : signed char16_t : unsigned char32_t : unsigned float : signed non-specialized : unsigned decltype(42) : signed
[edit] See also
| (C++11) |
checks if a type is a signed arithmetic type (class template) |
| [static] |
identifies integer types (public static member constant) |
| [static] |
identifies exact types (public static member constant) |
| [static] |
identifies types that represent a finite set of values (public static member constant) |
