for loop and range

A for loop goes through items one by one. With range() it runs a fixed number of times.

for i in range(5):
    print(i)        # 0 1 2 3 4   (5 is not included)

range has three forms:

• range(5) → 0, 1, 2, 3, 4
• range(1, 6) → 1, 2, 3, 4, 5
• range(0, 10, 2) → 0, 2, 4, 6, 8 (the third number is the step)

You can also loop over a string:

for ch in "hey":
    print(ch)

Use for when you know how many times to repeat. Use while when you repeat until something happens.