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Python String Reversal Examples

Mastering Python: A Comprehensive Guide to String Reversal

Introduction

In this post, we’ll delve into a fundamental concept – reversing strings in Python. Understanding string manipulation is important for any Python developer, and mastering the art of string reversal opens doors to various programming possibilities. In this guide, we’ll explore different approaches

String Reversal in Python

Example 1: Reversing Strings with Slicing

In this example we use slicing concepts of Python. In Python, slicing allows us to effortlessly reverse a string with just a few characters of code.

def reverse_string(input_str):
    return input_str[::-1]

# Example
print(reverse_string("Hello"))  

# Output: "olleH"

Example 2: Reversing Strings with a Loop

In this example, we’ll use a loop to iterate through each character and construct the reversed string.

def reverse_string(input_str):
    reversed_str = ""
    for char in input_str:
        reversed_str = char + reversed_str
    return reversed_str

# Example
print(reverse_string("Hello"))  

# Output: "olleH"

Example 3: Taking User Input

In this example, we will take string from user input and then reverse the string


def reverse_string(input_str):
    return input_str[::-1]

# Take input from the user
user_input = input("Enter a string: ")

# Example
print(reverse_string(user_input))

Example 4: Reverse each word in a given string while keeping the words in the same order

input: Learn Automation Testing 
output: nraeL noitamotuA gnitseT

Using Python List Comprehension

def reverse_words(input_str):
    words = input_str.split()  # Split the input string into a list of words
    reversed_words = [word[::-1] for word in words]  # Reverse each word
    result = ' '.join(reversed_words)  # Join the reversed words back into a string
    return result

# Take input from the user
user_input = input("Enter a string: ")

# Call the function and print the result
print(reverse_words(user_input))

Using a regular loop

# Function to reverse words in a string
def reverse_words(input_str):
    # Step 1: Split the input string into a list of words
    words = input_str.split()

    # Step 2: Initialize an empty list to store reversed words
    reversed_words = []

    # Step 3: Loop through each word in the list
    for word in words:
        # Step 4: Reverse each word and append it to the reversed_words list
        reversed_words.append(word[::-1])

    # Step 5: Join the reversed words back into a string
    result = ' '.join(reversed_words)

    # Step 6: Return the final result
    return result

# Step 7: Take input from the user
user_input = input("Enter a string: ")

# Step 8: Call the function with user input and print the result
print(reverse_words(user_input))

Now, let’s go through each step:

Step 1: The input string (input_str) is split into a list of words using the split() method. This creates a list called words where each element is a word from the original string.

Step 2: An empty list called reversed_words is initialized. This list will store the reversed version of each word.

Step 3: A for loop is used to iterate through each word in the words list.

Step 4: Inside the loop, each word is reversed using slicing (word[::-1]) and appended to the reversed_words list.

Step 5: After reversing all the words, the join() method is used to concatenate the reversed words into a single string. The words are separated by a space (‘ ‘) in this case.

Step 6: The final reversed string is stored in the variable result.

Step 7: The script takes input from the user using the input() function.

Step 8: The reverse_words function is called with the user input, and the reversed string is printed.

So, when the user enters a string, the code reverses each word in that string and prints the overall reversed string.

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