Methods or Functions

Method is a set of code which only runs when it is called. Methods are also known as Functions. Method is a code block that contains a series of statements. A program causes the statements to be executed by calling the method. In C++, every executed instruction is performed in the context of a method. We can pass data, known as parameters, into a method(We going to study this in detail in upcoming articles).

So far we written all our codes inside { and } of int main(), where main is nothing but a Method. We can create our own method. A method is defined with the name of the method, followed by parentheses().

NOTE
We can write entire new method before main method or we can write declaration before main method and definition after it. The most commonly used way is declaring method before main method and writing definition after it. so we followed the most common way in below code examples.

CODE

EG 1 . Creating a simple addition method and calling it in main method.

#include <iostream>
using namespace std;

//Method declaration
void Addition();

int main() {
    Addition(); // This is called as Calling a method or Invoking a Method
}

//Method definition
//We not yet studied what is void, we going to study it in upcoming articles.
void Addition() {
    int a = 5;
    int b = 6;
    int c = a + b;
    cout << c << endl;
}

OUTPUT
11

CODE EXPLANATION
In the above code, we created our own method called Addition. So far we written all our code inside { and } of int main(), that itself is a method. we cannot create a method inside a method. so we went outside } of Main method, created our own method called Addition. It doesn't matter how many methods you create , whatever code we written inside main method will only get executed since main method is the entry point of our program.
In the above case, System will initally enter main method . Inside main method we called Addition method. So system will enter Addition() and execute whatever code we written inside. Once all the code present inside Addition() executed, system will again enter inside main() and execute furthur codes if any.


EG 2 . Creating a multiplication table method and invoking inside main method.

#include <iostream>
using namespace std;

void MultiplicationTable();

int main() {
    MultiplicationTable();
}
void MultiplicationTable() {
    int tableNumber = 17;
    int limit = 20;
    for (int i=1; i <= limit; i++) {
        cout << tableNumber << " * " << i << " = " << tableNumber*i << endl;
    }
}

OUTPUT
17 * 1 = 17
17 * 2 = 34
17 * 3 = 51
17 * 4 = 68
17 * 5 = 85
17 * 6 = 102
17 * 7 = 119
17 * 8 = 136
17 * 9 = 153
17 * 10 = 170
17 * 11 = 187
17 * 12 = 204
17 * 13 = 221
17 * 14 = 238
17 * 15 = 255
17 * 16 = 272
17 * 17 = 289
17 * 18 = 306
17 * 19 = 323
17 * 20 = 340

CODE EXPLANATION
In the above code, We created our own method called MultiplicationTable, Inside that multiplication table we written code to print out 17th multiplication table upto the limit of 20. There is no point of creating this method without invoking inside main method since main method is the entry point of our Program. So we invoked Addition method inside main method.
Once we compile the program, system will go inside main method. Inside main() we are calling MultiplicationTable(), hence system will go inside MultiplicationTable() and execute whatever code we written inside. Once all the code present inside MultiplicationTable() executed, system will again enter inside main() and execute furthur codes if any.


Exercises
1. Create a method to print right angle triangle shape using *
2. Create a method to print 37th Multiplication Table upto the limit of 40


(Click Here, For more exercises)