std::numeric_limits<T>::is_signed
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.
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 (C++20) |
false |
char16_t (C++11) |
false |
char32_t (C++11) |
false |
short |
true |
unsigned short |
false |
int |
true |
unsigned int |
false |
long |
true |
unsigned long |
false |
long long (C++11) |
true |
unsigned long long (C++11) |
false |
float |
true |
double |
true |
long double |
true |
Example
#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
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) |
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