All language subtitles for 4- While

In the last lecture,

we wrote this for loop to display all the odd numbers

between 0 and 5. And in this lecture, I'm going to show you how to

implement the same logic by using a while loop. Now one

key difference between a y loop and a for loop is that in for loops

the loop variable is part of the loop variable itself.

But in y loops, you have to declare this y variable externally. Let me show

you what I mean. So we start with declaring

a variable like i and set it to 0. Note that this

i we have here is different from the i we have in this for loop,

because this variable is only meaningful and accessible

inside of this for loop. This is called scope, and I'm going to talk about

it later in the course, all I want you to know is that these two

variables are completely different, even though their names are the same.

Now, we have our loop variable initialized to 0.

Next we add a while statement,

in parenthesis we need to add our condition. What is the condition

here? That is i less than or equal

to 5. So I'm going to add that here. Next,

we need to add our statements. So what is the statement that

we want to repeat, here's the statement, we want to display

the odd numbers, so we add that here as well,

and finally, at the end of this while block we need

to increment i. So this is a direct translation

of this for loop into a y loop.

So this is what happens when we execute this code. Initially I

is 0, now in the y loop, first this condition

is evaluated, if this condition is true, then the

body of the y loop will be executed. Again, in the next iteration

the condition is evaluated again, if it's true, the

statements in the y block will be executed, otherwise the while block

will terminate. In the next lecture we're going to look at another kind of

loops in JavaScript.