Search the Web for a sample C program that interchanges the first and last digits of a number, and you can find many on different websites. Most of them employ a beautiful mathematical approach based on log10 or some similar feature to get the number of digitsand perform the swapping using additional math. But unfortunately, those who wrote such programs miss a bug -- this method won't work for numbers having trailing zeros.

For example, an input of will produce the output 21, which is incorrect. That's why I post my version here. It uses array, less fashionable compared to some math trick, but it works. Yes, this version also has limits. It can take trailing zeros, but it will trim the leading zeros, if any e. It isn't a problem since leading zeros has no mathematical significance. Also, it reprints the original input without the leading zeros in the output line, justifying what it does. Yes, you can write another version considering the leading zeros, if you receive the input as a string instead of an integer.

But suddenly the program will loose all of its math especially the idea of digit extractionand that's why I'm not doing it here. For example, after running this loop for the inputthe array is something like this: [5, 4, 3, 2, 1].

Now comes the output part. Printing digits[0] will give you the last digit of the input. Now we have to print the rest of the array elements excluding the last one, which is the first digit, actually in reverse order because the digits are stored in reverse order.

That's why there is a for loop. After that, we print digits[count - 1]the last element of the array, which happens to be the first digit. It simply means add the last digit of the number to the [current] last position of the array. Usually we use mouse with our right hand.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Interchanging the first and last digits of a number in C. I cracked the question using most basic knowledge of c. I haven't used any strings or arrays or bit-wise operator, just simple logic. I think it should be simpler I omit for sake of simplicity all checks on number range, functions return values and so on :.

Learn more. Interchanging the first and last digits of a number in C [closed] Ask Question. Asked 3 years, 7 months ago. Active 3 years, 7 months ago. Viewed 5k times. I'm not sure where your issue is, but this did make me think of an easier approach.

Why don't you use sprintf to convert the number to a string, then swap the first and last character? What do you want to happen when the last digit is 0? I'm voting to close this question as off-topic because it should be moved to codereview. Active Oldest Votes. Just for information. Shahid Shahid 2, 1 1 gold badge 11 11 silver badges 23 23 bronze badges. Jonathan Leffler k gold badges silver badges bronze badges.

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Related Hot Network Questions. Stack Overflow works best with JavaScript enabled.Then we will remove one digit at a time form number using below mentioned algorithm and then store the most significant digit in firstDigit variable.

To remove last least significant digit from number we will divide number by Toggle navigation Home. Write a C program to find sum of first and last digits of a number. Wap in C to find sum of least significant and most significant digit of a number.

Repeat above two steps, till number is greater than The remaining number is the first digit of number.

**Armstrong Number Program in C - C Language Tutorial - Mr. Srinivas**

Write a C program to find product of digits of a number using while loop. Wap in C to multiply the digits of a number. Repeat above two steps, till number is not equal to zero.

Newer Post Older Post Home. C program to print digit of a number in words. C program to add digits of a number. C program to count number of digits in an integer. C program to find sum of digits of a number using recursion. C program to reverse a number using recursion. C program to convert decimal number to octal number. C program to find perfect numbers between 1 to N using for loop. C program to print all factors of a number using for loop.

C program to print all prime factors of a number. List of all C programs.As for my assignment I had to write a program to swap 2 digit number Example:- If user input 12 the swaped number Would be Along with ALgorithm, and a short description on this program As how will you solve this program or what measure you'll take to get desired results.

Please Help. Have you started already? If not, why so? What in particular are you having difficulties with? As a hint: modulo 10, division by 10, multiplication by 10; you can pretty much solve your task using these operations. Apart from not following the standard and being unportable I'd say no.

Did you even try it out? Compile, run and answer your own question. If it doesn't compile, fix the compiler error, if it runs but doesn't produce the correct output, fix the bug and compile again.

Edited 7 Years Ago by mvmalderen. Is this correct Getting Started: Have something to contribute to this discussion? Please be thoughtful, detailed and courteous, and adhere to our posting rules. Edit Preview. H1 H2. Post Reply. Insert Code Block. Share Post.

Permanent Link.When modulo divided by 10 returns its last digit. To find first digit of a number we divide the given number by 10 until number is greater than At the end we are left with the first digit. Important note: log10 is a mathematical function present in math. It returns log base 10 value of the passed parameter to log10 function. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.

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## How to swap numbers of four digits numbers using c#?

Given a number and to find first and last digit of a number. Python3 program to find first and. Remove last digit from number.

Python3 program to find first. Find total number of digits - 1. Find first digit. Return first digit. Log10 n. Pow 10, digits. N Find a Number X whose sum with its digits is equal to N. Mithun Kumar. Check out this Author's contributed articles. Load Comments.Given a number x and two positions from the right side in the binary representation of x, write a function that swaps n bits at given two positions and returns the result. It is also given that the two sets of bits do not overlap. Solution We need to swap two sets of bits.

XOR can be used in a similar way as it is used to swap 2 numbers. Following is the algorithm. References: Swapping individual bits with XOR. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above. Writing code in comment? Please use ide.

### Find first and last digits of a number

Position of rightmost set bit Binary representation of a given number Find position of the only set bit How to swap two numbers without using a temporary variable? Find the two non-repeating elements in an array of repeating elements Find the element that appears once Detect if two integers have opposite signs Count total set bits in all numbers from 1 to n Swap bits in a given number Add two numbers without using arithmetic operators Smallest of three integers without comparison operators A Boolean Array Puzzle Program to count number of set bits in an big array Next higher number with same number of set bits Optimization Techniques Set 1 Modulus Add 1 to a given number Multiply a given Integer with 3.

Python program to. Move all bits of first. Moce all bits of second. XOR the two sets. Put the xor bits back. XOR the 'xor' with the. Recommended Posts: Swap all odd and even bits Swap every two bits in bytes How to swap two bits in a given integer?

### how do i swap digits

Check if bits of a number has count of consecutive set bits in increasing order Toggle bits of a number except first and last bits Number of ways to swap two bit of s1 so that bitwise OR of s1 and s2 changes Bit manipulation Swap Endianness of a number Maximize a given unsigned number number by swapping bits at it's extreme positions. Check if a number has same number of set and unset bits Set all even bits of a number Set all odd bits of a number Same Number Of Set Bits As N Largest number less than X having at most K set bits Number with set bits only between L-th and R-th index Check whether the number has only first and last bits set.

Load Comments.Given a two-digit integer, swap its digits and print the result.

Example input. By signing up or logging in, you agree to our Terms of service and confirm that you have read our Privacy Policy. Download Our App. New Questions Please suggest me a very good book to learn java is it good to read documentation? It is very much confusion for most of the beginners please suggest - Java. I have a doubt on one of the questions asked in Codechef, could you please help me out with that? Create a class named 'PrintNumber' to print various numbers of different datatypes by creating different methods with the same name 'printn' having a - Java.

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