std::is_move_assignable C++ with Examples

The std::is_move_assignable template of C++ STL is present in the <type_traits> header file. The std::is_move_assignable template of C++ STL is used to check whether the T is a move assignable type(that can be assigned an rvalue reference of the same type) or not. It return the boolean value true if T is move assignable type otherwise return false.

Header File:

#include<type_traits>

Template Class:

template <class T>
struct is_move_assignable;

Syntax:

std::is_move_assignable<T>::value

Parameters: The template std::is_move_assignable accepts a single parameter T(Trait class) to check whether T is move assignable or not.

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

• True: If the type T is a move assignable type.
• False: If the type T is not a move assignable type.

Below is the program to illustrates the std::is_move_assignable template in C/C++:

Program:

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

// Declare structures
struct A {
};

struct B {
    B& operator=(B&) = delete;
};

struct C {
    ~C() = delete;
};

// Driver Code
int main()
{

    cout << boolalpha;

    // Check if int is move
    // assignable or not
    cout << "int: "
         << is_move_assignable<int>::value
         << endl;

    // Check if struct A is move
    // assignable or not
    cout << "struct A: "
         << is_move_assignable<A>::value
         << endl;

    // Check if struct B is move
    // assignable or not
    cout << "struct B: "
         << is_move_assignable<B>::value
         << endl;

    // Check if struct C is move
    // assignable or not
    cout << "struct C: "
         << is_move_assignable<C>::value
         << endl;

    // Declare an map
    unordered_multimap<int, string> m;
    m.insert({ 1, "GfG" });

    // Check if map m is move
    // assignable or not?
    cout << "Map m: "
         << is_move_assignable<decltype(*m.begin())>::value;

    return 0;
}

Output:

int: true
struct A: true
struct B: false
struct C: true
Map m: true

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