is_signed template in C++

The std::is_signed template of C++ STL is used to check whether the type is a signed arithmetic type or not.

Syntax:

template <class T > struct is_signed;

Parameters: This template contains single parameter T (Trait class) to check whether T is a signed arithmetic type or not.

Return Value: This template returns a boolean value as shown below:

• True: if the type is a signed arithmetic type.
• False: if the type is a un-signed arithmetic type.

Below programs illustrate the std::is_signed template in C++ STL:

Program 1:

// C++ program to illustrate
// std::is_signed template

#include <iostream>
#include <type_traits>
using namespace std;

class gfg {
};

enum sam : int {};
enum class raj : int {};

int main()
{
    cout << boolalpha;
    cout << "is_signed:" << '\n';
    cout << "int:" << is_signed<int>::value << '\n';
    cout << "gfg:" << is_signed<gfg>::value << '\n';
    cout << "sam:" << is_signed<sam>::value << '\n';
    cout << "raj:" << is_signed<raj>::value << '\n';
    return 0;
}

Output:

is_signed:
int:true
gfg:false
sam:false
raj:false

Program 2:

// C++ program to illustrate
// std::is_signed template

#include <iostream>
#include <type_traits>
using namespace std;

int main()
{
    cout << boolalpha;
    cout << "is_signed:" << '\n';
    cout << "float:"
         << is_signed<float>::value << '\n';
    cout << "signed int:"
         << is_signed<signed int>::value << '\n';
    cout << "unsigned int:"
         << is_signed<unsigned int>::value << '\n';
    return 0;
}

Output:

is_signed:
float:true
signed int:true
unsigned int:false

Program 3:

// C++ program to illustrate
// std::is_signed template

#include <iostream>
#include <type_traits>
using namespace std;

int main()
{
    cout << boolalpha;
    cout << "is_signed:" << '\n';
    cout << "bool:" << is_signed<bool>::value << '\n';
    cout << "unsigned char:"
         << is_signed<unsigned char>::value << '\n';
    cout << "signed char:"
         << is_signed<signed char>::value << '\n';
    cout << "double:"
         << is_signed<double>::value << '\n';

    return 0;
}

Output:

is_signed:
bool:false
unsigned char:false
signed char:true
double:true