Loops

To perform repetative actions, we use loops. It performs iteration over the elements of sequences, such as lists, tuples, set, range, strings, and dictionaries.

for...in loop

syntax

# variable will hold first element of the sequence
# and will change next iteration
for <variable> in <sequence>:
    # action with each element of the sequence

# variable will be created in global scope
# and will be accessible from the whole code

example with list

my_list = [1, 2, 3, 4, 5]

# prints all elements of the list
for x in my_list:
    print(x)

example with tuple

my_tuple = (1, 2, 3, 'abc', True, False)

# prints all elements of the tuple
for x in my_tuple:
    print(x)

example with dictionary

prints all keys of the dictionary. also we can access value using the key.

my_guitar = {
    'brand': 'Gibson',
    'model': 'SG',
}

for x in my_guitar:
    print(x, my_guitar[x])

items() method return tuple of the key and value.

for item in my_guitar.items():
    print(item)
# ('brand', 'Gibson')
# ('model', 'SG')

we can also unpack the tuple

# key, value = item
for key, value in my_guitar.items():
    print(key, value)

example with set

prints all elements of the set

my_set = {1, 2, 3, 4, 5}

for x in my_set:
    print(x)

example with string

prints all characters of the string

my_string = 'Hello World'

for chr in my_string:
    print(chr)

example with range

prints all numbers from 0 to 9

for num in range(10):
    print(num)

while loop

we use condition to control the loop. The loop runs until the condition is False. Infinite loop can be created using while True.

syntax

while condition:
    # action

example

print all numbers from 1 to 9

num = 1

while num < 10:
    print(num)
    num += 1

example with break

run infinite loop initially and break/exit the loop if the answer is yes.

while True:
    answer = input('Do you want to stop? ')
    if answer == 'yes':
        break

example with continue

number guessing game. continue skips the rest of the code in the loop and goes to the next iteration.

import random

random_num = random.randint(1, 10)

while True:
    guess = int(input('Guess a number between 1 and 10: '))
    if guess == random_num:
        print('You got it!')
        break
    print('Wrong guess, Try again!')
    continue