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C Program to Swap First and Last Digit Of a Number

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In this article, we will show you, 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 1

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.

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

/* C Program to Swap 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;
  	
  	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;
}

OUTPUT

C Program to Swap First and Last Digit Of a Number 1

ANALYSIS
Number = 4578

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 user to enter any number, and then swap first and last digit in that number

/* C Program to Swap 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;
}

OUTPUT

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

ANALYSIS
From the above 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

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