When should we use a for loop, a while loop, and a while True loop?

Deciding between a for loop, a while loop, and a while True loop mostly depends on whether you know when the loop should stop.

An easy way to think about it is:

1. If you know ahead of time how many times the loop should run (like looping through numbers from 1 to 10), a for loop is usually the better choice. For example,

for i in range(5):
    print("Hello", i)

This will print "Hello" five times. You clearly know it runs 5 times.

2. If you don’t know exactly how many times the loop should run and you're waiting for a certain condition to be met (like user input), a while loop makes more sense.

number = int(input("Enter a number (0 to stop): "))

while number != 0:
    print("You entered:", number)
    number = int(input("Enter a number (0 to stop): "))

Here, you keep asking for input until the user enters 0. You don’t know how many times that will be, so while is a better fit.

3. while True is a special case used when you want an infinite loop that stops only when a condition inside the loop tells it to break. It’s powerful but should be used carefully.

while True:
    command = input("Type 'exit' to stop: ")
    if command == 'exit':
        break
    print("You typed:", command)

Here, the loop keeps running no matter what until the user types "exit". It’s flexible, but if you forget the break or the condition is wrong, the loop may never stop.