std::is_convertible template in C++ with Examples

The std::is_convertible template of C++ STL is present in the <type_traits> header file. The std::is_convertible template of C++ STL is used to check whether any data type A is implicitly convertible to any data type B. It returns the boolean value either true or false.

Header File:

#include<type_traits>

Template Class:

template< class From, class To >
struct is_convertible;

template< class From, class To >
struct is_nothrow_convertible;

Syntax:

is_convertible <A*, B*>::value;

Parameters: It takes two data type of A and B as:

• A: It represents the parameter to be converted.
• B: It represents the parameter in which parameter A is implicitly converted.

Return Value:

• True: If a given data type A is converted into data type B.
• False: If a given data type A is not converted into data type B.

Below is the program to demonstrate std::is_convertible in C++:

Program:

// C++ program to illustrate
// std::is_convertible example
#include <bits/stdc++.h>
#include <type_traits>
using namespace std;

// Given classes
class A {
};
class B : public A {
};
class C {
};

// Driver Code
int main()
{
    cout << boolalpha;

    // Check if class B is
    // convertible to A or not
    bool BtoA = is_convertible<B*, A*>::value;
    cout << BtoA << endl;

    // Check if class A is
    // convertible to B or not
    bool AtoB = is_convertible<A*, B*>::value;
    cout << AtoB << endl;

    // Check if class B is
    // convertible to C or not
    bool BtoC = is_convertible<B*, C*>::value;
    cout << BtoC << endl;

    // Check if int is convertible
    // to float or not
    cout << "int to float: "
         << is_convertible<int, float>::value
         << endl;

    // Check if int is convertible
    // to const int or not
    cout << "int to const int: "
         << is_convertible<int, const int>::value
         << endl;

    return 0;
}

Output:

true
false
false
int to float: true
int to const int: true

Reference: http://www.cplusplus.com/reference/type_traits/is_convertible/