While loop

while condition:
	some work

Until the condition is true the loop will keep on working.

x = 4
while x == 4:
	print("Hello There!")

The above code will keep on printing Hello There! infinitely.

x = 0
while x <= 4:
	print("Hello There!")
	x = x + 1

The above code will print Hello There! 5 times.

x before increment x after increment Is x <= 4 applicable ? Will print Hello There! or not ?
0 1 Yes Yes
1 2 Yes Yes
2 3 Yes Yes
3 4 Yes Yes
4 5 No Yes

Key Breakdown

  • The loop runs while x <= 4.
  • When x = 4, it still satisfies the condition, so it increments x to 5 and prints "Hello".
  • Now, x = 5, so the condition x <= 4 fails.
  • The loop immediately stops before printing anything further.
  • The condition x <= 4 depends on the original x at the start of each iteration because:

    • Condition Check First: while x <= 4

    • The loop checks x before executing the body.

    • Then x is Incremented: x = x + 1

    • The increment happens inside the loop, after the condition has already been checked.

  • x = 0 , check the condition , it is true print hello there, increment x by 1, check the condition again , again it is true , print hello there and it will keep going until x = 4, then the loop will break.