Array access

Learn 0-based indexing and O(1) access.

Looping through an array

To visit every element of an array, use a for x in arr: loop. This processes each element in order.

If you also need the index, write for i in range(len(arr)):. This lets you use both the index and the element.

To print each element on its own line, call print(x) inside the loop. This takes O(n) time.

To see the whole array on one line, print(arr) is enough; it shows the list representation of the array.

Write print_all(arr). Print each element with for. Call print_all([5, 10, 15]) to print 5, 10, 15.

Show example solution

def print_all(arr):
    # Print each element
    for x in arr:
        print(x)
print_all([5, 10, 15])

Loop structure

To iterate array elements: ____ x in arr:

Show answer

To iterate array elements: for x in arr: