Python Strings Exercise and Solutions

Question 1 : How can we count all the characters in the string and create a dictionary of the result?

Given String:

str = "I love Logical Python. Python is one of the most used Programming Language."

Expected Output: Count of each character

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We need to iterate over the string and find the count of each character

str = "I love Logical Python. Python is one of the most used Programming Language."

#unique letters so that we are not looping the long string.
unique_letters = set(str)

letters_count = {}


for letter in unique_letters:
    letters_count[letter] = str.count(letter)
    
print(letters_count)

Output:

{'d': 1, '.': 2, 'I': 1, 'l': 2, 's': 3, 'P': 3, 'v': 1, 'c': 1, 'h': 3, 'f': 1, 'g': 5, 'm': 3, 'y': 2, 'i': 3, 'n': 5, 'a': 4, 't': 4, 'e': 5, 'u': 2, 'L': 2, 'r': 2, ' ': 12, 'o': 8}

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Question 2 : Write a Program to fetch numbers from the string.

Given String:

x = "I love*2 Logical Python * 25"

Expected Output:

225

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Two ways we can fetch numbers from the string:

1. Using the for loop.

x = "I love*2 Logical Python * 25"

numbers = ""
for i in x:
    if (i.isdigit()):
        numbers = numbers + i

print(numbers)

2. Using the list comprehensions.

x = "I love*2 Logical Python * 25"

list_of_numbers = [i for i in x if i.isdigit()]
numbers = "".join(list_of_numbers)

print(numbers)

Output:

225

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Question 3 : How can we find the first and last occurrence index of the sub string from the string?

Given String:

str = "I love Logical Python. Python is one of the most used Programming Language. That is why i love it."

Expected Output:

2
90

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For this, we have to use the find and rfind string methods.

str = "I love Logical Python. Python is one of the most used Programming Language. That is why i love it."

print(str.find('love'))
print(str.rfind('love'))

Output:

2
90

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Question 4 : How can we remove the special characters from the string?

Given String:

x = "I love* you #Logical #Python"

Expected Output:

x = I love you Logical Python 

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Using the string package and for loop.

import string

x = "I love* you #Logical #Python"

print()

for i in string.punctuation:
    if i in x:
        x = x.replace(i,"")
        
print("x =",x)

Output:

x = I love you Logical Python 

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Question 5 : What is the output of the below code? If it is an error, then what changes we can make to fix this error?

Given String:

str = "LogicalPython"
print(str.index("Best"))

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Answer:

The index() method returns the “substring not found” error if the sub-string is not found in the string. To escape from the error, we can use the find() methods. It will return -1 if the substring is not found.

Using find() method:

str = "LogicalPython"
print(str.find("Best"))

Output:

-1

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Question 6 : Write a program in python to check if the string is a palindrome?

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Without using slicing:

str = "hannah"
length = len(str)
mid = length//2

for i in range(mid):
    if str[i] != str[-1-i]:
        print("String is not palindrome.")
        break;
else:
    print("String is a palindrome.")

Output:

String is a palindrome.

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Question 7 : Write a program to capitalize every next letter of the string.

Given String:

logical

Output:

LoGiCaL

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Solution:

str = "logical"

length = len(str)
str2 = ""

for i in range(length):
    if i%2 == 0:
        str2 += str[i].upper()
    else:
        str2 += str[i]

print(str2)

Output:

LoGiCaL

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Question 8 : Write a program to check if the given email belongs to the “@logical.com” domain.

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Solution:

email = input("Please enter your email id : ")
domain = "@logical.com"
len_email = len(email)
len_domain = len(domain)
if len_email == len_domain:
    print("Please enter complete email address.")
else:
    if email[len_email-len_domain:] == domain:
        print("Your email is valid")
    else:
        print("Your email is invalid")

Output:

Please enter your email id : abc@logical.com
Your email is valid

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Question 9 : Write a program to find all the locations of a character from the string.

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Solution:

str = input("Please enter the string : ")
character = input("Please enter the character : ")

print("Index Locations:")
for i in range(len(str)):
    if str[i] == character:
        print(i)

Output:

Please enter the string : Logical Python
Please enter the character : o
Index Locations:
1
12

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