Python Basics: Using break, continue, and Nested Loops

Break and continue keywords

Both keywords are used inside Python loops. break terminates the entire loop, typically used to exit an infinite loop, while continue skips the current iteration and proceeds to the next one.

num = 0
while num < 5:
    if num == 3:
        num += 1
        break
    print(num)
    num += 1

Output: 0 1 2 When num == 3, the loop ends and the value 3 is not printed.

num = 0
while num < 5:
    if num == 3:
        num += 1
        continue
    print(num)
    num += 1

Output:

0
1
2
4

Nested loops

Python allows while and for loops to be nested, usually up to three levels. In a double loop, the outer loop controls rows and the inner loop controls the number of items per row.

Example: printing a 3‑row, 4‑column rectangle of asterisks using a for loop.

# for‑loop nested example
for i in range(0, 3):
    for j in range(0, 4):
        print("*", end="\t")
    print()  # newline after each row

Output:

****
****
****

Same pattern using a while loop.

i = 0
while i < 3:
    j = 0
    while j < 4:
        print("*", end=" ")
        j += 1
    i += 1
    print()  # newline after each row

Output:

****
****
****