C++ function within a function

Function inside a function in Python

It is pretty easy for python to define a function within a function. Such as

def print_hello_world():
    def print_I_love_world():
        print("I love world")
    print_I_love_world()
    print_I_love_world()

What about C++?

#include<iostream>
using namespace std;
int main()
{
    
    void print_I_love_world()
    {
        cout<<"I love world"<<endl;
        return;
    }
    print_I_love_world();
    cout<<"Hello world"<<endl;
    return 0;
}

You will get some errors

function_in_function.cpp:6:5: error: function definition is not allowed here
{
^
function_in_function.cpp:10:5: error: use of undeclared identifier 'print_I_love_world'
print_I_love_world();
^
2 errors generated.

How to make it work?

#include<iostream>
using namespace std;
int main()
{
    
    /*void print_I_love_world()
    {
        cout<<"I love world"<<endl;
        return;
    }
    */
    function<void(void)> print_I_love_world = []()
    {
        cout<<"I love world"<<endl;
        return; 
    };
    print_I_love_world();
    cout<<"Hello world"<<endl;
    return 0;
}

A real problem

See this post: the first solution to the second problem if you wanna check a sample code.

More advanced practice can be found HERE.

Thanks for reading.