This article discloses the Python Program to Reverse a Number using Python While Loop, Functions, and Recursion.
Python Program to Reverse a Number Using While Loop
This python program to reverse a number allows the user to enter any positive integer. Then, this Python program reverses a number using Python While Loop
# Python Program to Reverse a Number using While loop Number = int(input("Please Enter any Number: ")) Reverse = 0 while(Number > 0): Reminder = Number %10 Reverse = (Reverse *10) + Reminder Number = Number //10 print("\n Reverse of entered number is = %d" %Reverse)
This program to reverse a number in python allows the user to enter any positive integer. Then that number is assigned to variable Number.
Next, Condition in the While loop makes sure that the given number is greater than 0.
From the above Python example, User Entered value: Number = 1456 and Reverse = 0
First Iteration
Reminder = Number %10
Reminder = 1456%10 = 6
Reverse = Reverse *10 + Reminder
Reverse = 0 * 10 + 6 = 0 + 6 = 6
Number = Number //10
Number = 1456 //10 = 145
Second Iteration
From the Python While Loop first Iteration, the values of both the Number and Reverse changed as Number = 145 and Reverse = 6
Reminder = Number % 10
Reminder = 145 % 10 = 5
Reverse = Reverse *10+ Reminder = 6 * 10 + 5
Reverse = 60 + 5 = 65
Number = Number //10 = 145 //10
Number = 14
Third Iteration
From the Second Iteration of Python reverse a Number program, Number = 14 and Reverse = 65
Reminder = Number %10
Reminder = 14%10 = 4
Reverse = Reverse *10+ Reminder = 65 * 10 + 4
Reverse = 650 + 4 = 654
Number = Number //10 = 14//10
Number = 1
Fourth Iteration
From the third Iteration, Number = 1 and Reverse = 654
Reminder = Number %10
Reminder = 1 %10 = 1
Reverse = Reverse *10+ Reminder = 654 * 10 + 1
Reverse = 6540 + 1 = 6541
Number = Number //10 = 1//10
Number = 0
Here, For the next iteration, Number = 0. So, the while loop condition fails.
Program to Reverse a Number Using Functions
This program to reverse a number in python allows the user to enter any positive integer. Then we are going to reverse a number using the reverse Functions.
# Python Program to Reverse a Number using Functions def Reverse_Integer(Number): Reverse = 0 while(Number > 0): Reminder = Number %10 Reverse = (Reverse *10) + Reminder Number = Number //10 return Reverse Number = int(input("Please Enter any Number: ")) Reverse = Reverse_Integer(Number) print("\n Reverse of entered number is = %d" %Reverse)
Within this reverse number in a program, When it reaches to Reverse = Reverse_Integer (Number) line in the program then the compiler immediately jump to below function:
def Reverse_Integer(Number):
The last line ends with a return Reverse statement.
Python Program to Reverse a Number using Recursion
This program to reverse a number allows the user to enter any positive integer. And then, we are going to reverse a number using Python Recursion
# Python Program to Reverse a Number using Recursion Reverse = 0 def Reverse_Integer(Number): global Reverse if(Number > 0): Reminder = Number %10 Reverse = (Reverse *10) + Reminder Reverse_Integer(Number //10) return Reverse Number = int(input("Please Enter any Number: ")) Reverse = Reverse_Integer(Number) print("\n Reverse of entered number is = %d" %Reverse)
In this reverse a number program, When the compiler reaches to Reverse = Reverse_Integer (Number) line in the program then the compiler immediately jump to below function:
def Reverse_Integer(Number):
In this reverse number function, the below statement helps to call the function Recursively with the updated value. If you miss this statement, then after completing the first line, it terminates.
Reverse_Integer(Number //10)
For example, Number = 459 produces the output as 9
Let’s see the Python If Statement,
if (Number > 0), check whether the number is greater than 0 or not. For Recursive functions, it is essential to place a condition before using the function recursively. Otherwise, we end up in infinite execution (Same like infinite Loop).