Write a Python program to Reverse a String using For Loop, while loop, and Functions with an example. In this programming language, there is no built-in string method to reverse the characters.
String Reverse in Python using slicing
If we use the negative value inside the slice, it reads string characters from last to first.
txt = "New York" rev = txt[::-1] print("Original = ", txt) print("Reversed =", rev)
Python Program to Reverse a String using For Loop
This program allows the user to enter any sentence. Next, this code reverses the string using For Loop.
st1 = input("Please enter your own : ") st2 = '' for i in st1: st2 = i + st2 print("\nOriginal = ", st1) print("After = ", st2)
You can observe from the above program screenshot that the word is Coding.
For Loop First Iteration: for i in st1
=> for C in Coding
str2 = C + st2=> C + ”
Second Iteration: for o in Coding
st2 = o + C => oC
Using for loop range function
An alternative approach uses the for loop range function with the start value as the last character, stop as the first char, and step as the negative one to read from last to first.
txt = "New York" rev = "" for i in range(len(txt) - 1, -1, -1): rev += txt[i] print(rev)
Using for loop index
It reads characters based on the index position and reverses the items.
txt = "New York City" rev = "" for i in range(len(txt)): rev = txt[i] + rev print(rev)
ytiC kroY weN
Python Program to reverse a String using While Loop
This program using the while loop is the same as above. However, we just replaced the For Loop with While Loop. Here, the len function is used to find the length of the total characters in a sentence.
# using a while loop a = input("Please enter your own : ") b = '' i = len(a) - 1 while(i >= 0): b = b + a[i] i = i - 1 print("\nThe Original = ", a) print("The Inverted = ", b)
Python Program to Reverse String using Function
It is another way of reversing a string using functions.
def StrInverse(str1): str2 = str1[::-1] return str2 a = input("Please enter your own : ") b = StrInverse(a) print("\nOriginal = ", a) print("After = ", b)
Using slice join function
txt = "New Jersey" rev = "".join(txt[::-1]) print(rev)
Using join and reversed function
This example uses the join and reversed functions to reverse a given string.
txt = "New Jersey" rev = "".join(reversed(txt)) print(rev)
import collections library deque function
from collections import deque txt = "New York City Hall" dq = deque(txt) dq.reverse() rev = "".join(dq) print(rev)
llaH ytiC kroY weN
Python Program to Reverse String using Recursion
We are doing string reverse in this code by calling the function recursively.
# using recursive function def StrInverted(str1): if(len(str1) == 0): return str1 else: return StrInverted(str1[1:]) + str1 str2 = input("Please enter your own : ") str3 = StrInverted(str2) print("\nThe Original = ", str2) print("The Inversed = ", str3)