The std::is_pointer template of C++ STL is used to check whether the given type is pointer or not. It returns a boolean value showing the same.
Syntax:
template <class T > struct is_pointer;
Parameter: This template accepts a single parameter T (Trait class) to check whether T is a pointer or not.
Return Value: This template returns a boolean value as shown below:
- True: if the type is a pointer.
- False: if the type is a non-pointer.
Below programs illustrate the std::is_pointer template in C++ STL:
Program 1:
// C++ program to illustrate // is_pointer template #include <iostream> #include <type_traits> using namespace std;
// main program class GFG {
}; int main()
{ cout << boolalpha;
cout << "is_pointer:"
<< endl;
cout << "GFG: "
<< is_pointer<GFG>::value << '\n' ;
cout << "GFG*: "
<< is_pointer<GFG*>::value << '\n' ;
cout << "GFG&: "
<< is_pointer<GFG&>::value << '\n' ;
cout << "nullptr_t: "
<< is_pointer<nullptr_t>::value << '\n' ;
return 0;
} |
Output:
is_pointer: GFG: false GFG*: true GFG&: false nullptr_t: false
Program 2:
// C++ program to illustrate // is_pointer template #include <iostream> #include <type_traits> using namespace std;
// main program int main()
{ cout << boolalpha;
cout << "is_pointer:"
<< endl;
cout << "int: "
<< is_pointer< int >::value << '\n' ;
cout << "int *: "
<< is_pointer< int *>::value << '\n' ;
cout << "int **: "
<< is_pointer< int **>::value << '\n' ;
cout << "int ***: "
<< is_pointer< int ***>::value << '\n' ;
return 0;
} |
Output:
is_pointer: int: false int *: true int **: true int ***: true
Program 3:
// C++ program to illustrate // is_pointer template #include <iostream> #include <type_traits> using namespace std;
// main program int main()
{ cout << boolalpha;
cout << "is_pointer:" << endl;
cout << "int *&: "
<< is_pointer< int *&>::value << '\n' ;
cout << "int *[10]: "
<< is_pointer< int * [10]>::value << '\n' ;
cout << "float *: "
<< is_pointer< float *>::value << '\n' ;
cout << "int[10]:"
<< is_pointer< int [10]>::value << '\n' ;
return 0;
} |
Output:
is_pointer: int *&: false int *[10]: false float *: true int[10]:false