What are user defined functions in C++?

Programming Language
#1

A user-defined function groups code to perform a specific task and that group of code is given a name (identifier).

When the function is invoked from any part of the program, it all executes the codes defined in the body of the function.

CODE:

#include <iostream>
using namespace std;

// declaring a function
int add(int a, int b) {
    return (a + b);
}

int main() {
    int sum;
    sum = add(100, 78);
    cout << "100 + 78 = " << sum << endl;
    return 0;
}