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Python Program to Reverse a Number Using While Loop

  • This program allows the user to enter any positive integer and then, this program will reverse a number using Python While Loop
 Python Program to Reverse a Number

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Sample Code

# 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)

OUTPUT

 Python Program to Reverse a Number Using While Loop

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Analysis:

  • This program allows the user to enter any positive integer and then, that number is assigned to variable Number.
  • Next, Condition in the While loop will make sure that, the given number is greater than 0
  • From the above 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
Reverse = 0 + 6
Reverse = 6
Number = Number //10
Number = 1456 //10
Number = 145

Second Iteration

From the first Iteration the values of both Number and Reverse has been changed as:
Number = 145 and Reverse = 6
Reminder = Number % 10
Reminder = 145 % 10 = 5
Reverse = Reverse *10+ Reminder
Reverse = 6 * 10 + 5
Reverse = 60 + 5
Reverse = 65
Number = Number //10
Number = 145 //10
Number = 14

Third Iteration

From the Second Iteration the values of both Number and Reverse has been changed as:
Number = 14 and Reverse = 65
Reminder = Number %10
Reminder = 14%10 = 4
Reverse = Reverse *10+ Reminder
Reverse = 65 * 10 + 4
Reverse = 650 + 4
Reverse = 654
Number = Number //10
Number = 14//10
Number = 1

Fourth Iteration

From the Second Iteration the values of both Number and Reverse has been changed as:
Number = 1 and Reverse = 654
Reminder = Number %10
Reminder = 1 %10 = 1
Reverse = Reverse *10+ Reminder
Reverse = 654 * 10 + 1
Reverse = 6540 + 1
Reverse = 6541
Number = Number //10
Number = 1//10
Number = 0

  • Here, For the next iteration Number = 0 so, the while loop condition will fail

Python Program to Reverse a Number Using Functions

  • This program allows the user to enter any positive integer and then, we are going to reverse a number using Python Functions

Sample Code

# 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)

OUTPUT

 Python Program to Reverse a Number Using Functions

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ANALYSIS:

  • When the compiler reaches to Reverse = Reverse_Integer (Number) line in the program then the compiler will immediately jump to below function:
def Reverse_Integer(Number):
  • We already explained the code LOGIC in the above example. Please refer Python Program to Reverse an Integer Using While Loop Analysis.
  • Last line ends with return Reverse statement.

Python Program to Reverse a Number using Recursion

  • This program allows the user to enter any positive integer and then, we are going to reverse a number using Python Recursion

Sample Code

# 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)

OUTPUT

 Python Program to Reverse a Number using Recursion

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ANALYSIS:

  • When the compiler reaches to Reverse = Reverse_Integer (Number) line in the program then the compiler will immediately jump to below function:
def Reverse_Integer(Number):
  • In this function, below statement will help to call the function Recursively with updated value.
  • If you miss this statement then, after completing the first line it will terminate.
Reverse_Integer(Number //10)
  • For example, Number = 459 will produce the output as 9
  • Lets see the Python If Statement, if (Number > 0) will check whether the number is greater than 0 or not. For Recursive functions it is very important to place a condition before using the function recursively otherwise, we will end up in infinite execution (Same like infinite Loop).

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