Passing Parameter

Parameter is the variable listed inside the parentheses in the method definition. An argument is the actual value that is sent to the function when it is called. We can create a method with n number of Parameters inside. when a method is called, a new storage location is created for each parameters.

CODE

EG 1 . Creating a multiplication table method with table number and limit as Parameters.

#include <iostream>
using namespace std;

void MultiplicationTable(int tableNumber, int limit);

int main() {
    MultiplicationTable(17,20);
}

//Here table number and limit are the Parameters. Whenever this method invoked those 2 parameters value must be assigned.
void MultiplicationTable(int tableNumber, int limit) {
    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
Function wise, the code what we written above is same as that of Eg 2 what we seen before in methods or functions topic. The only difference between previous one and this one is, In previous example we created table number and limit inside a method so that value will be assigned inside method itself but here table number and limit are created as parameters so that the parameters value will be assigned once the method is invoked.


EG 2 . Creating a method to print Right angle triangle shape using * and passing row value as parameter.

#include <iostream>
using namespace std;

void PrintRightAngleTraingleShape(int row);

int main() {
    PrintRightAngleTraingleShape(10);
}
void PrintRightAngleTraingleShape(int row) {
    for (int i=1;i<=row;i++) {
        for (int j=1;j<=i;j++) {
        cout << "*";
        }
    cout << endl;
    }
}

OUTPUT
*
**
***
****
*****
******
*******
********
*********
**********

CODE EXPLANATION
In the above code, we created a method called PrintingRightAngleTriangleShape where we populated that method with logic of printing out right angle triangle shape using '*'. We passed row as the parameter to the method. Inside main method we invoked PrintingRightAngleTriangleShape() by passing 10 as the parameter value(Argument). If we compile above program, system will print out right angle triangle shape using '*' in 10 rows.


What is the use of methods, where to use it?
A method is a set of code grouped together to perform certain operation. Method is used to achieve the reusability of code. We write a method once and use it many times. We do not require to write code again and again. By simply changing the parameter values we can get our desired output.
Let us take the above MultiplicationTable() as example, Above we are printing out 17th Multiplication Table upto the limit of 30. Suppose if we want to print out 37th multiplication table upto the limit to 50, No need to write the loop and other codes again and again we can simply invoke MultiplicationTable() again and pass table number value as 37 and limit value as 50. Now system will print out 37th multiplication table upto the limit of 50. Try executing following code inside main method multiplicationTable(37,50);

Exercises
1. Create a method to print Triangle shape using '*', pass row value as parameter.
    sample output:
    if user gives argument as 3
      *
    ***
  *****
2. Create a method to print Inverse Triangle shape using '*', pass row value as parameter.
    sample output:
    if user gives argument as 3
    *****
      ***
        *


(Click Here, For more exercises)