is_signed template in C++

In this article we will be discussing the working, syntax and examples of std::is_signed template in C++ STL.

is_ signed is a template which comes under <type_traits> header file. This template is used to check whether the given type T is a signed type or not.

What is a signed type?

These are the basic arithmetic types, which contains sign value with them. All arithmetic data types are either signed and unsigned.

Like we want to show the values in negative we use signed type.

Like: -1 is signed int and -1.009 is signed float.

By default all the types are signed to make them unsigned we have to prefix the data type by unsigned.

Syntax

template <class T> is_signed;

Parameters

The template can have only parameter of type T, and check whether T is a signed type or not.

Return value

It returns a Boolean value, true if the given type is a Signed type, and false if the given type is not a signed type.

Example

Input: is_signed<int>::value;
Output: True

Input: is_signed<unsigned int>::value;
Output: False

Example

 Live Demo

#include <iostream>
#include <type_traits>
using namespace std;
class TP {
};
enum TP_1 : int {};
enum class TP_2 : int {};
int main() {
   cout << boolalpha;
   cout << "checking for is_signed:";
   cout << "\nint:" << is_signed<int>::value;
   cout << "\nTP:" << is_signed<TP>::value;
   cout << "\nTP_1:" << is_signed<TP_1>::value;
   cout << "\nTP_2:" << is_signed<TP_2>::value;
   return 0;
}

Output

If we run the above code it will generate the following output −

checking for is_signed:
Int: true
TP: false
TP_1: false
TP_2: false

Example

 Live Demo

#include <iostream>
#include <type_traits>
using namespace std;
int main() {
   cout << boolalpha;
   cout << "checking for is_signed:";
   cout << "\nfloat:" << is_signed<float>::value;
   cout << "\nSigned int:" << is_signed<signed int>::value;
   cout << "\nUnsigned int:" << is_signed<unsigned int>::value;
   cout << "\ndouble:" << is_signed<double>::value;
   return 0;
}

Output

If we run the above code it will generate the following output −

checking for is_signed:
Float: true
Signed int: true
Unsigned int: false
Double: true