C++ Loops

Loops are basically means to do a task multiple times, without actually coding all statements over and over again.
For example, loops can be used for displaying a string many times, for counting numbers and of course for displaying menus.
Loops in C++ are mainly of three types :-

1. 'while' loop
2. 'do while' loop
3. 'for' loop

The 'while' loop :-
Let me show you a small example of a program which writes ABC three(3) times.

01	#include<iostream>

02

03	int main()

04

{

05

int i=0;

06	while(i<3)

07

{

08

i++;

09	cout<<"ABC"<<endl;

10

}

11

}

The output of the above code will be :- ABC ABC ABC

The 'do while' loop :-
It is very similar to the 'while' loop shown above. The only difference being, in a 'while' loop, the condition is checked beforehand, but in a 'do while' loop, the condition is checked after one execution of the loop.

Example code for the same problem using a 'do while' loop would be :-

01	#include <iostream>

02	int main()

03

{

04

int i=0;

05

do

06

{

07

i++;

08	cout<<"ABC"<<endl;

09

}while(i<3);

} // main end

The 'for' loop :- This is probably the most useful and the most used loop in C++. The general syntax can be defined as :- for(<initial value>;<condition>;<increment>) To further explain the above code, we will take an example. Suppose we had to print the numbers 1 to 5, using a 'for' loop. The code for this would be :- 1 #include<iostream> 2 3 int main() 4 { 5   for(inti=1;i<=5;i++) 6   cout<<i<<endl; 7 }