Start learning free

LESSON 148 OF 677 · WHILE LOOPS & FOR LOOPS

While loop in Kotlin

Lesson

A while loop allows your program to perform a set of instructions as long as a condition is satisfied.

Here is the structure of a while loop:

while(condition) {
	instruction1
	instruction2
	...
}

Let's check an example:

var count = 1
while (count <= 5) {
	println("I made a mistake")
	count++
}
println("Finished!")

The output of this program is:

I made a mistake
I made a mistake
I made a mistake
I made a mistake
I made a mistake
Finished!

And this is what the computer does behind the scenes during this loop:

0. Creates and initializes a variable count = 1

1. First iteration:
	a. Is count <= 5 true? <=> Is 1 <= 5 true? Yes. 
	b. println("I made a mistake") => Output: I made a mistake
	c. count++ => count becomes 2
	
2. Second iteration:
	a. Is count <= 5 true? <=> Is 2 <= 5 true? Yes. 
	b. println("I made a mistake") => Output: I made a mistake
	c. count++ => count becomes 3
	
3. Third iteration:
	a. Is count <= 5 true? <=> Is 3 <= 5 true? Yes. 
	b. println("I made a mistake") => Output: I made a mistake
	c. count++ => count becomes 4
	
4. Fourth iteration:
	a. Is count <= 5 true? <=> Is 4 <= 5 true? Yes. 
	b. println("I made a mistake") => Output: I made a mistake
	c. count++ => count becomes 5

5. Fifth iteration:
	a. Is count <= 5 true? <=> Is 5 <= 5 true? Yes. 
	b. println("I made a mistake") => Output: I made a mistake
	c. count++ => count becomes 6
	
6. Sixth iteration:
	a. Is count <= 5 true? <=> Is 6 <= 5 true? No. 
	b. Terminate the loop.

	
7. println("Finished!") => Output: Finished!

Pro Tip:

A while loop is essentially an if statement that repeats itself over and over until the condition becomes false.


Assignment

Let's print "I promise to learn coding" 5 times using a loop.


Hint
Look at the examples above if you get stuck.


STEP 1 OF 4
    Ctrl + Enter to check