While loop

The while loop is another kind of a loop structure in Python. The while loop executes a given block of code repeatedly if certain requirements are met or based on a boolean condition and stop the while loop when the condition is false.

With the while loop we can execute a set of statements as long as a condition is True.

i = 1
while i < 5:
    print(i)
    i += 1

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Basic rules for using the while loop:

• Initialized the variables.

• While the loop executes, update the variable.

• The code at some time return a False condition to avoid an infinite loop.

With the break statement we can stop the loop even if the while condition is True.

i = 1

while True:
    print(i)
    i = i + 1
    if i > 5:
        break

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With the continue statement we can stop the current iteration, and continue with the next.

i = 0

while i < 5:
  i += 1
  if i == 3:
    continue  # skip to next if i == 3
  print(i)

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Usage of For and While loop

For loop If you know, prior to the start of loop, how many times you want to repeat the loop.

While loop If you don’t know of a certain number of runs and a set of conditions are to be met.

age = 20
person_age = int(input("Enter your age: "))

while person_age in range(0, 30):
    if person_age <= 17:
        print("You are not allowed.")
        break
    if person_age >= 18:
        print("You are allowed.")
        break

You are allowed.