type_traits::alignment_of template in C++

It is used to find the member constant value equal to the alignment requirement of the type T. If T is a reference type than it returns the alignment requirements of the type referred to. If T is an array type than it returns the alignment requirements of the element type.
Header File: 

#include<type_traits>

Syntax: 

template
  <class T>
  struct alignment_of;

Parameter: The template std::alignment_of accepts a single parameter T (Trait class).
Below programs illustrate the std::alignment_of template in C++ STL:
Program 1:

CPP14

// C++ program to illustrate
// assignment_of template

#include <bits/stdc++.h>
#include <type_traits>
using namespace std;

class GFG {
};

// main method
int main()
{
    cout << alignment_of<GFG>::value << endl;
    cout << alignment_of<int>() << endl;
    cout << alignment_of<double>() << endl;

    return 0;
}

Output:

1
4
8

Program 2:

CPP14

// C++ program to illustrate
// assignment_of template

#include <bits/stdc++.h>
#include <type_traits>
using namespace std;

class GFG {
};

// main method
int main()
{
    cout << alignment_of<GFG>::value << endl;
    cout << alignment_of<float>() << endl;
    cout << alignment_of<char>() << endl;

    return 0;
}

Output:

1
4
1

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