Finally, we can actually change the iterator – the number of steps taken on each loop. Code. Copy Text for x in range(2, 20, 3): ... How to use “while” loops in Python.

$ python iterator_test.py 463 926 1389 1852 Let’s take a look at what’s going on. We made our own class and defined a __next__ method, which returns a new iteration every time it’s called.

In general, for loops are used when you know exactly how many times you plan to run a loop; a while loop is used when the number of iterations is uncertain. Conditional Statement Basic Structure: if ...