std::is_signed

Defined in header `<type_traits>`
template< class T > struct is_signed;		(since C++11)

If T is a signed arithmetic type, provides the member constant value equal true. For any other type, value is false.

Inherited from std::integral_constant

Member constants

value

[static]

true if T is a signed arithmetic type , false otherwise
(public static member constant)

Member functions

operator bool

converts the object to bool, returns value
(public member function)

Member types

Type	Definition
`value_type`	`bool`
`type`	std::integral_constant<bool, value>

[edit] Example

Run this code

#include <iostream>
#include <type_traits>
 
class A {};
enum B : int {};
enum class C : int {};
 
int main() 
{
    std::cout << std::boolalpha;
    std::cout << std::is_signed<A>::value << '\n';
    std::cout << std::is_signed<float>::value << '\n';
    std::cout << std::is_signed<signed int>::value << '\n';
    std::cout << std::is_signed<unsigned int>::value << '\n';
    std::cout << std::is_signed<B>::value << '\n';
    std::cout << std::is_signed<C>::value << '\n';
}

Output:

false
true
true
false
false
false

[edit] See also

is_unsigned (C++11)	checks if a type is unsigned arithmetic type (class template)
is_signed [static]	identifies signed types (public static member constant of `std::numeric_limits`)
is_floating_point (C++11)	checks if a type is floating-point type (class template)
is_integral (C++11)	checks if a type is integral type (class template)
make_signed (C++11)	makes the given integral type signed (class template)
make_unsigned (C++11)	makes the given integral type unsigned (class template)

Language
Standard library headers
Concepts
Utilities library
Strings library
Containers library
Algorithms library
Iterators library
Numerics library
Input/output library
Localizations library
Regular expressions library (C++11)
Atomic operations library (C++11)
Thread support library (C++11)

Type support (basic types, RTTI, type traits)
Dynamic memory management
Error handling
Program utilities
Variadic functions
Date and time
Function objects
initializer_list (C++11)
bitset
hash (C++11)
Relational operators
rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>=
Pairs and tuples
pair
tuple (C++11)
piecewise_construct_t (C++11)
piecewise_construct (C++11)
Swap, forward and move
swap
forward (C++11)
move (C++11)
move_if_noexcept (C++11)
declval (C++11)