Loops

Question 1

Loops

Answer 1

Loops are used to run a specific instruction or a set of instructions to execute again and again until certain condition is met

Question 2

Analogy

Answer 2

Imagine a kid sitting in a car. The kid will keep asking ‘When will we reach’ again and again until we reach home. So, ‘reaching home’ is the constraint here and the kid asking ‘When will we reach’ is performed in a loop until the constraint is met

Question 3

For loop - Basic Syntax

Answer 3

syntax:
for i in range(5):
print(i)

Output:
0
1
2
3
4

Every for loop starts at 0 unless specified and goes on until one number before the specified number in the range

Question 4

For loop - Specific start and end range

Answer 4

for i in range(5,10):
print(i)

Output:
5
6
7
8
9

Question 5

For loop - Start, Stop, Step

Answer 5

for i in range(0,10,2):
print(i)

Output:
0
2
4
6
8

Question 6

While loop

Answer 6

For loop - Domestic Loop (iterator is controlled by the code)

While Loop - Wild Loop! We have to take care of the loop

Question 7

While Loop

Answer 7

timer = 5
while timer != 0:
print(timer)
timer = timer - 1

Output:
5
4
3
2
1

Question 8

Trivia Time!

timer = 10
while timer != 10:
print(timer)

Answer 8

Infinite number of 10s!
Since we are not updating the condition/iterator - timer

Question 9

Trivia Time!

timer = 10
while timer == 11:
print(timer)
timer = timer - 1

Answer 9

Nothing will be printed because the entry ticket to enter the while door is that the timer has to be 10.

Since that condition is not met, the while loop is not executed.

Question 10

Practice 1

Write a python code to print N numbers (1 to N included) using for-loop. Get the value for N from the user

Answer 10

n = input(‘Enter N: ‘)
for i in range (1,N+1):
print(i)

Question 11

Practice 2

Calculate the sum of first N numbers

Answer 11

n = input(‘Enter N: ‘)
total = 0

for i in range(1,N+1):
total = total + i

Question 12

Iterating through an array

Elements of an array are called through their index numbers.

For example, the elements of the array vegetables = […] are referenced as vegetable[1], vegetable[2], etc…

Answer 12

vegetables = [‘carrot’, ‘beans’, ‘beetroot’, ‘pumpkin’, ‘broccoli’, ‘radish’]

length = len(vegetables)
for i in range(length):
print(vegetables[i])

Question 13

Question: Counting vowels and consonants in a string

Hint: A string is also considered as an array and can be referenced using index

Answer 13

name = ‘gnanambhal shivarraman’
vowels = 0
consonants = 0

length = len(name)
for i in range(length):
if name[i] == ‘a’ or name[i] == ‘e’ or name[i] == ‘i’ or name[i] == ‘o’ or name[i] == ‘u’:
vowels = vowels + 1
else if name[i] == ‘ ‘:
continue
else:
consonants = consonants + 1

print(vowels)
print(consonants)