is_fundamental Template in C++

The is_fundamental template of C++ STL is used to check whether the type is a fundamental type or not. It returns a boolean value showing the same.

Syntax:

template <class T> struct is_fundamental;

Parameter: This template accepts a single parameter T (Trait class) to check whether T is a fundamental type or not.

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

• True: if the type is a fundamental.
• False: if the type is a non-fundamental.

Below programs illustrate the is_fundamental template in C++ STL:

Program 1:

// C++ program to illustrate
// is_fundamental template

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

// main program
class GFG {
};

int main()
{
    cout << boolalpha;
    cout << "is_fundamental:"
         << '\n';
    cout << "GFG :"
         << is_fundamental<GFG>::value
         << '\n';
    cout << "int :"
         << is_fundamental<int>::value
         << '\n';
    cout << "int& :"
         << is_fundamental<int&>::value
         << '\n';
    cout << "int* :"
         << is_fundamental<int*>::value
         << '\n';

    return 0;
}

Output:

is_fundamental:
GFG :false
int :true
int& :false
int* :false

Program 2:

// C++ program to illustrate
// is_fundamental template

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

// main program
int main()
{
    cout << boolalpha;
    cout << "is_fundamental:"
         << '\n';
    cout << "float:"
         << is_fundamental<float>::value
         << '\n';
    cout << "float&:"
         << is_fundamental<float&>::value
         << '\n';
    cout << "float*:"
         << is_fundamental<float*>::value
         << '\n';
    cout << "double:"
         << is_fundamental<double>::value
         << '\n';
    cout << "double&:"
         << is_fundamental<double&>::value
         << '\n';
    cout << "double*:"
         << is_fundamental<double*>::value
         << '\n';

    return 0;
}

Output:

is_fundamental:
float:true
float&:false
float*:false
double:true
double&:false
double*:false

Program 3:

// C++ program to illustrate
// is_fundamental template

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

// main program
int main()
{
    cout << boolalpha;
    cout << "is_fundamental:"
         << '\n';
    cout << "char:"
         << is_fundamental<char>::value
         << '\n';
    cout << "char&:"
         << is_fundamental<char&>::value
         << '\n';
    cout << "char*:"
         << is_fundamental<char*>::value
         << '\n';
    cout << "void :"
         << is_fundamental<void>::value
         << '\n';

    return 0;
}

Output:

is_fundamental:
char:true
char&:false
char*:false
void :true