while

Question

I dont understand it well . Can anyone give a breif summary about it???

Answer 1

Suppose you want to print from 1000 to 2000. Since writing -

cout<<"1000";
cout<<"1001";
....
cout<<"2000";

is not a good practice, you'll have to use loop. There are 3 types of loops : while, for, do-while.

To write a while loop you'll have to keep 4 components in mind:

1. initialization: where to start from (like 1000)
2. body of loop (like, cout << 1000)
3. iteration: what will be the next value (like 1001, 1002 ... they are incremented by one)
4. condition: when to stop (like when it's 2000, we won't go for 2001)

So, the code should be like:

int i = 1000; // initialization, it executes once
while ( i <= 2000) // condition
cout << i << endl; // loop body
i = i + 1; // iteration
}

So, i starts from 1000. Then the condition is checked - Is i less than or equal to 2000? If yes, i is printed and incremented, so it becomes 1001. Again the condition is checked and the whole process is repeated until i becomes 2001. when i is 2001, the condition is false and the loop is stopped.