How to write for loops in Python

Patrick Loeber

A for loop is used for iterating over a sequence. This can be for example a list, a tuple, a dictionary, a set, a string, or a range object.

To use a for loop we use the for x in sequence syntax.

With the for loop we can execute a set of statements, once for each item in the sequence.

numbers = [1, 2, 3] for x in fruits: print(x)
1 2 3

Loop with the range function

To loop over numbers and use the current index, we can use the range function.

for i in range(3): print(i)
0 1 2

Range can take only a stop argument, or a start and a stop argument. In the latter case it can also take an optional step argument:

Loop through a String

Looping through a string will go over each character.

for x in "python": print(x)
p y t h o n

The break statement

The break statement can be used for an early stopping of the loop before it has looped through all the items. Typically this is applied when a certain condition is met.

values = ["one", "two", "three"] for value in values: print(x) if value == "two": break
one two

The continue statement

The continue statement is used to skip the current iteration.

values = ["one", "two", "three"] for value in values: if value == "two": continue print(x)
one three

Note that here the print statement is applied at the end of each iteration, so after the possible continue statement.

Advanced looping with enumerate

With enumerate(x) we can access both the index and the item:

values = ["one", "two", "three"] for idx, value in enumerate(values): print(idx, value)
0 one 1 two 2 three

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