How to Reverse a String in Python?

One of our machine learning team members was working on a requirement to reverse a string in Python. I suggested a few useful methods to do it. In this tutorial, I will show you how to reverse a string in Python using different methods with examples.

To reverse a string in Python using slicing, you can use the concise syntax reversed_string = original_string[::-1]. This method works by starting at the end of the string and moving backward with a step of -1, effectively reversing the string. For example, if original_string = "California", then reversed_string = original_string[::-1] will yield “ainrofilaC”.

Reverse a String in Python

Now, let me show you how to reverse a string in Python using different methods with examples.

Method 1: Using Slicing

Slicing is one of the best ways to reverse a string in Python. It’s concise and easy to understand.

Syntax:

reversed_string = original_string[::-1]

The slicing method uses the [::-1] syntax, which means “start at the end of the string and end at position 0, move with the step -1 (or simply, one step backward).”

Now, let me show you an example to help you understand this.

Example:

original_string = "New York" reversed_string = original_string[::-1] print(reversed_string) # Output: kroY weN

I executed the above Python code using VS code, and you can see the output in the screenshot below:

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Method 2: Using the reversed() Function

If you want to know how to reverse a string in Python without slicing, then you can check this method and example. Here, we will use the reversed() function to reverse a Python string.

The reversed() function returns an iterator that accesses the given sequence in the reverse order. You can then join these characters to form the reversed string.

Syntax:

reversed_string = ''.join(reversed(original_string))

The reversed() function does not directly return a string but an iterator. You need to use the join() method to combine these characters into a new string.

Here is an example.

Example:

original_string = "California" reversed_string = ''.join(reversed(original_string)) print(reversed_string) # Output: ainrofilaC

You can see the exact output in the screenshot below:

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Method 3: Using a Loop

If you prefer a more manual approach, you can use a loop to reverse a string. This is also another useful way to reverse a string in Python using a for loop.

Syntax:

reversed_string = '' for char in original_string: reversed_string = char + reversed_string

This method iterates through each character in the original string and prepends it to the reversed_string.

Let me show you an example.

Example:

original_string = "Texas" reversed_string = '' for char in original_string: reversed_string = char + reversed_string print(reversed_string) # Output: saxeT

Here is the output in the screenshot below:

Method 4: Using Recursion

Recursion can also be used to reverse a string in Python. This method is less common but can be an interesting exercise in understanding recursive functions.

Syntax:

def reverse_string(s): if len(s) == 0: return s else: return reverse_string(s[1:]) + s[0]

This function calls itself with a smaller substring (excluding the first character) and appends the first character at the end.

Let us understand this by writing a Python program to reverse a string.

Example:

original_string = "Florida" reversed_string = reverse_string(original_string) print(reversed_string) # Output: adirolF

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Method 5: Using Stack

A stack data structure can also be used to reverse a Python string. This method involves pushing all string characters onto a stack and then popping them to get the reversed string.

Syntax:

def reverse_string_stack(s): stack = list(s) reversed_string = '' while stack: reversed_string += stack.pop() return reversed_string

Stacks follow a Last In First Out (LIFO) principle, making them ideal for reversing strings.

Here is an example to help you understand it better.

Example:

def reverse_string_stack(s): stack = list(s) reversed_string = '' while stack: reversed_string += stack.pop() return reversed_string original_string = "Washington" reversed_string = reverse_string_stack(original_string) print(reversed_string) # Output: notgnihsaW

I executed the above Python code, and you can see the exact output in the screenshot below:

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Write a Python Program to Reverse a String

Let me show you how to write a Python program to reverse a string.

Here’s a Python program that demonstrates how to reverse a string using slicing:

# Original string original_string = "Washington" # Reverse the string using slicing reversed_string = original_string[::-1] # Print the reversed string print(reversed_string) # Output: notgnihsaW

Explanation:

1. Define the Original String: We start by defining the string we want to reverse, in this case, “Washington”.
2. Apply Slicing: We use the slicing syntax [::-1] to reverse the string. This creates a new string that is the reverse of original_string.
3. Print the Result: Finally, we print the reversed string, which will output “notgnihsaW”.

You can see the output in the screenshot below:

Conclusion

In this tutorial, I explained how to reverse a string in Python using different methods with examples.

• Using Slicing
• Using the reversed() Function
• Using a Loop
• Using Recursion
• Using Stack

However, I always recommended using the slicing method to reverse a Python string. I hope these examples help you learn how to reverse a string in Python.

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