How do you reverse a string in python without function?

Question

This is a Python Program to reverse a string without using recursion.

Table of Contents Show

3. Use join
How do I reverse a string in Python manually?
How do you reverse a string without using the reverse method?
How many ways can you reverse a string in Python?

Problem Description

The program takes a string and reverses the string without using recursion.

Problem Solution

1. Take a string from the user.
2. Use string slicing to reverse the string.
3. Print the reversed string.
4. Exit.

Program/Source Code

Here is source code of the Python Program to reverse a string without using recursion. The program output is also shown below.

a=str(input("Enter a string: "))
print("Reverse of the string is: ")
print(a[::-1])

Program Explanation

1. User must enter a string.
2. By giving the increment value as -1, string slicing is used to reverse the list.
3. The reversed string is printed.

Runtime Test Cases

 
Case 1:
Enter a string: hello
Reverse of the string is: 
olleh
 
Case 2:
Enter a string: test
Reverse of the string is: 
tset

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Educative Answers Team

In Python, strings are ordered sequences of character data.

There is no built-in method to reverse a string. However, strings can be reversed in several different ways.

Methods

Three methods to reverse a string are explained below:

1. Slicing

Strings can be reversed using slicing. To reverse a string, we simply create a slice that starts with the length of the string, and ends at index 0.

To reverse a string using slicing, write:

stringname[stringlength::-1] # method 1

Or write without specifying the length of the string:

stringname[::-1] # method2

The slice statement means start at string length, end at position 0, move with the step -1 (or one step backward).

s="Python" # initial string
stringlength=len(s) # calculate length of the list
slicedString=s[stringlength::-1] # slicing 



print (slicedString) # print the reversed string

2. Loop

To start, let’s create a new array called reversedString[].

We can then loop over the list with iterating variable index initialized with the length of the list.

In each iteration, concatenate value of str[index-1] with reverseString
Decrement the index.

We then simply keep iterating until the index is less than zero.

s = "Python" # initial string
reversedString=[]
index = len(s) # calculate length of string and save in index
while index > 0: 
    reversedString += s[ index - 1 ] # save the value of str[index-1] in reverseString
    index = index - 1 # decrement index



print(reversedString) # reversed string

3. Use join

This is a powerful technique that takes advantage of Python’s iterator protocol. This technique reverses a string using reverse iteration with the reversed() built-in function to cycle through the elements in the string in reverse order and then use .join() method to merge all of the characters resulting from the reversed iteration into a new string.

The general syntax is

s="Python" 
reversedstring=''.join(reversed(s))

The following Python code demonstrates the concept.

s = 'Python' #initial string
reversed=''.join(reversed(s)) # .join() method merges all of the characters resulting from the reversed iteration into a new string
print(reversed) #print the reversed string