C Program to Swap First and Last Digit Of a Number

How to write a C Program to Swap First and Last Digit Of a Number with an example?.

C Program to Swap First and Last Digit Of a Number Example

This program allows the user to enter any number. And then, it is going to swap the First Digit and Last Digit of the user-entered value.

#include <stdio.h>
#include <math.h>
 
int main()
{
  	int Number, FirstDigit, DigitsCount, LastDigit, a, b, SwapNum;
 
  	printf("\n Please Enter any Number that you wish  : ");
  	scanf("%d", & Number);
  	
  	DigitsCount = log10(Number); 	
  	FirstDigit = Number / pow(10, DigitsCount);
  	
  	LastDigit = Number % 10;
  	
  	a = FirstDigit * (pow(10, DigitsCount));
  	b = Number % a;
  	Number = b / 10;
  	
  	SwapNum = LastDigit * (pow(10, DigitsCount)) + (Number * 10 + FirstDigit);
	    
	printf(" \n The Number after Swapping First Digit and Last Digit =  %d", SwapNum);
 
  	return 0;
}

For this Program to Swap First and Last Digit Of a Number demonstration, the User entered Number = 4578

We already explained the Analysis part in our previous articles. So, Please refer First Digit and Last Digit article in C Programming to understand the same.

DigitCount = log10(Number) = 3
FirstDigit = 4578 / pow(10, 3) = 4578 / 1000 = 4.578 = 4
LastDigit = 4578 % 10 = 8

a = FirstDigit * (pow(10, DigitsCount))
a = 4 * pow(10, 3)  = 4 * 1000 = 4000

b = Number % a = 4578 % 4000 = 578
Number = 578 / 10 = 57.8 = 57

SwapNum = LastDigit * (pow(10, DigitsCount)) + (Number * 10 + FirstDigit)
SwapNum = 8 * pow(10, 3) + (57 * 10 + 4)
SwapNum = 8000 + (570 + 4) = 8574

C Program to Swap First and Last Digit Of a Number Example 2

This program also allows the user to enter any number, and then swap the first and last digit of a number

#include <stdio.h>
#include <math.h>
 
int main()
{
  	int Number, FirstDigit, DigitsCount, LastDigit, a, b, SwapNum;
 
  	printf("\n Please Enter any Number that you wish  : ");
  	scanf("%d", & Number);
  	
  	DigitsCount = log10(Number); 	
  	FirstDigit = Number / pow(10, DigitsCount);
  	
  	LastDigit = Number % 10;
  	
  	SwapNum = LastDigit;
  	SwapNum = SwapNum  * (round(pow(10, DigitsCount)));
  	SwapNum = SwapNum + Number % (int)(round(pow(10, DigitsCount)));
  	SwapNum = SwapNum - LastDigit;
  	SwapNum = SwapNum + FirstDigit;
	    
	printf(" \n The Number after Swapping First Digit and Last Digit =  %d", SwapNum);
 
  	return 0;
}

 Please Enter any Number that you wish  : 95371
 
 The Number after Swapping First Digit and Last Digit =  15379

From the above Program to Swap First and Last Digit Of a Number example, you can see that the user entered value = 95371.

DigitsCount = 4
FirstDigit = 9
LastDigit = 1
SwapNum = LastDigit = 1

SwapNum = SwapNum * (round(pow(10, DigitsCount))) = 1 * pow(10, 4) = 10000.
SwapNum = SwapNum + Number % (round(pow(10, digitsCount))).
SwapNum = 10000 + (95371 % pow(10, 4)).
SwapNum = 10000 + 95371 % 10000 = 10000 + 5371 = 15371.
SwapNum = SwapNum – LastDigit = 15371 – 1 = 15370.
SwapNum = SwapNum + FirstDigit = 15370 + 9 = 15379.