- C Programming Examples
- C Programming Examples
- C Print Hello World
- C Get Input from User
- C Print Integer
- C Add Two Numbers
- C Add Subtract Multiply Divide
- C Add n Numbers
- C Area Perimeter of Square
- C Area Perimeter of Rectangle
- C Area Circum of Circle
- C Fahrenheit to Celsius
- C Celsius to Fahrenheit
- C Inches to Centimeters
- C Kilogram to Gram
- C Reverse a Number
- C Swap Two Numbers
- C Interchange Numbers
- C Print ASCII Value
- C Print Fibonacci Series
- C Check Palindrome or Not
- C Check Armstrong or Not
- C Find Armstrong Numbers
- C Find nCr and nPr
- C Find Profit Loss
- C Sum of their Square
- C First & Last Digit Sum
- C Sum of All Digit
- C Product of All Digit
- C Print Total Digit in Number
- C Check Perfect Number
- C Find Basic Gross Salary
- C Round Number to Integer
- C Print Series upto n Term
- C Find Factors of Number
- C if-else & Loop Programs
- C Check Even or Odd
- C Check Prime or Not
- C Check Alphabet or Not
- C Check Vowel or Not
- C Check Leap Year or Not
- C Is Reverse Equal Original
- C Make Calculator
- C Add Digits of Number
- Count Positive Negative Zero
- C Largest of Two Numbers
- C Largest of Three Numbers
- C Smallest of Two Numbers
- C Smallest of Three Numbers
- C Find Factorial of Number
- C Find LCM & HCF
- C Find LCM of n Numbers
- C Find HCF of n Numbers
- C Find Arithmetic Mean
- C Find Average, Percentage
- C Find Student Grade
- C Print Table of Number
- C Print Prime Numbers
- C Find Discount Purchase
- C Calculate Parcel Charge
- C Calculate Wage of Labor
- C Print Phone Bill
- C Conversion programs
- C Decimal to Binary
- C Decimal to Octal
- C Decimal to Hexadecimal
- C Binary to Decimal
- C Binary to Octal
- C Binary to Hexadecimal
- C Octal to Decimal
- C Octal to Binary
- C Octal to Hexadecimal
- C Hexadecimal to Decimal
- C Hexadecimal to Binary
- C Hexadecimal to Octal
- C Pattern Programs
- C Pattern Printing Programs
- C Print Diamond Pattern
- C Print Floyd's Triangle
- C Print Pascal's Triangle
- C Array Programs
- C 1D Array Programs
- C Linear Search
- C Binary Search
- C Largest Element in Array
- C Smallest Element in Array
- C Second Largest/Smallest
- C Count Even Odd
- C Array Element at Even
- C Array Element at Odd
- C Print Even Array Elements
- C Print Odd Array Elements
- C Sum/Product of Even/Odd
- C Reverse an Array
- C Insert Element in Array
- C Delete Element from Array
- C Merge Two Arrays
- C Bubble Sort
- C Selection Sort
- C Insertion Sort
- C Print Common Elements
- C 2D Array Programs
- C Add Two Matrices
- C Subtract Two Matrices
- C Transpose a Matrix
- C Multiply Two Matrices
- C Sum All Matrix Elements
- C Largest Element in Matrix
- C Print Row Column Total
- C 3D Array Programs
- C String Programs
- C Print String
- C Find Length of String
- C Compare Two String
- C Copy a String
- C Concatenate String
- C Reverse a String
- C Count Vowels Consonants
- C Replace Vowel in String
- C Delete Vowels from String
- C Delete Word from String
- C Frequency of Character
- C Count Word in String
- C Remove Spaces from String
- C Sort a String
- C Sort String in Alphabetical
- C Sort Words in Ascending
- C Sort Words in Descending
- C Uppercase to Lowercase
- C Lowercase to Uppercase
- C Swap Two Strings
- C Check Anagram or Not
- C Check Palindrome String
- C Print Number in Words
- C Print Successive Character
- C Character without Space
- C Remove Extra Spaces
- C File Programs
- C Read a File
- C Write Content to File
- C Read & Display File
- C Copy a File
- C Merge Two Files
- C Reverse File
- C Count All Character in File
- C List Files in Directory
- C Encrypt & Decrypt a File
- C Delete a File
- C Misc Programs
- Generate Random Numbers
- C Print Date Time
- C Print Message with Time
- C Get IP Address
- C Print Smiling face
- C Pass Array to Function
- Add Two Numbers using Pointer
- C Address of Variable
- C Shutdown Computer
- C Programming Tutorial
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# C Program to Swap Two Numbers

In this article, you will learn and get code on swapping of two numbers in C language using following approaches:

- using third Variable
- without using third Variable
- using Function and Pointer

### What is Swapping of Two Numbers ?

Swapping of two numbers means, first number becomes second and second number becomes first. For example, if user
enters any two number say 10 and 20. And let's suppose the two variables say **num1** and **num2** holds
these two numbers. That is, *num1=10* and *num2=20*. Then after swapping it will be like *num1=20* and *num2=10*

## Swap Two Numbers Using third Variable

Swapping of two numbers in C, becomes easy using third variable. That is, this
program uses a variable named *temp* that helps a lot while performing the swap operation of given two numbers by
user at run-time. Let's take a look at the program first

#include<stdio.h> #include<conio.h> int main() { int num1, num2, temp; printf("Enter Two Numbers:-\n"); printf("First Number: "); scanf("%d", &num1); printf("Second Number: "); scanf("%d", &num2); printf("\nBefore Swap:\n"); printf("First Number = %d\tSecond Number = %d", num1, num2); temp = num1; num1 = num2; num2 = temp; printf("\n\nAfter Swap:\n"); printf("First Number = %d\tSecond Number = %d", num1, num2); getch(); return 0; }

This program was build and run under *Code::Blocks* IDE. Here is its sample run:

Now enter the first number say *10* and then second number say *20*. Press `ENTER`

key to see the following output:

The main block of code for swapping of two numbers is:

temp = num1; num1 = num2; num2 = temp;

For example, if user enters 10 as first number, then 10 gets initialized to *num1*. And if user enters 20
as second number, then 20 gets initialized to *num2*. That is, **num1=10** and **num2=20**.

Now after executing the statement:

temp = num1;

The value of *num1* (that is 10) gets initialized to *temp*. Therefore, **temp=10**. And after executing the statement:

num1 = num2;

The value of *num2* (that is 20) gets initialized to *num1*. Therefore, **num1=20**. And again after executing the statement:

num2 = temp;

The value of *temp* (that is 10) gets initialized to *num2*. Therefore, **num2=10**. In this way,
now the variable *num1* holds the value that initially *num2* has. Whereas the variable *num2* holds
the value that initially *num1* has.

**Note - ** Don't forgot to initialize the value of *num1* to any third variable before initializing the value of *num2* to it.

## Swap Two Numbers Without using third Variable

Unlike the previous program, this program will not use any type of extra (third) variable in __neither__ direct __nor__ in-direct way:

#include<stdio.h> #include<conio.h> int main() { int num1, num2; printf("Enter Two Numbers:-\n"); printf("First Number: "); scanf("%d", &num1); printf("Second Number: "); scanf("%d", &num2); printf("\nBefore Swap:\n"); printf("First Number = %d\tSecond Number = %d", num1, num2); num1 = num1+num2; num2 = num1-num2; num1 = num1-num2; printf("\n\nAfter Swap:\n"); printf("First Number = %d\tSecond Number = %d", num1, num2); getch(); return 0; }

This program will produce the same output as of previous one. The following block of code is responsible for swapping of given two numbers. Here I've used the addition and subtraction operation:

num1 = num1+num2; num2 = num1-num2; num1 = num1-num2;

For example, let's suppose 10 and 20 are the two numbers entered by user. Therefore. **num1=10** and
**num2=20**. Now after executing the following statement:

num1 = num1+num2;

The value comes from *num1+num2* (that will be 10+20) gets initialized to *num1*. Therefore, **num1=30**.
Again after executing the following statement:

num2 = num1-num2;

The value comes from *num1-num2* (that will be 30-20) gets initialized to *num2*. Therefore, **num2=10**.
And again after executing the statement given below:

num1 = num1-num2;

The value comes from *num1-num2* (that will be 30-10) gets initialized to *num1*. Therefore, **num1=20**.
Now the value of first variable goes to second and the value of second variable goes to first one.

### The Concept of Using + and - for Swapping

If there are two numbers. Suppose first number becomes total. Then if you subtract second number from total,
you'll get the first number. Therefore it gets initialized to *num2* (that now holds the initial value of *num1*). Again if you
subtract the new value of second number (initial value of first number) from total, then you will get the initial value of second number.
Therefore it gets initialized to *num1* (that now holds the initial value of *num2*).

## Swap Two Numbers Using Function and Pointer

This is the last program on swapping of two numbers. This program uses a user-defined function named **swapFun()**
to swap the given two numbers by user:

#include<stdio.h> #include<conio.h> void swapFun(int *, int *); int main() { int num1, num2; printf("Enter Two Numbers:-\n"); printf("First Number: "); scanf("%d", &num1); printf("Second Number: "); scanf("%d", &num2); printf("\nBefore Swap:\n"); printf("First Number = %d\tSecond Number = %d", num1, num2); swapFun(&num1, &num2); printf("\n\nAfter Swap:\n"); printf("First Number = %d\tSecond Number = %d", num1, num2); getch(); return 0; } void swapFun(int *num1, int *num2) { int temp; temp = *num1; *num1 = *num2; *num2 = temp; }

This program also produces the same output as of previous two programs.

In above program, the **&** is called as __address of__ operator. Whereas the ***** is called as
__value at__ operator. Therefore using the *address of* operator, we've passed the address of both the variables
say *num1* and *num2* (that holds the two numbers entered by user) to the function named *swapFun()*.

And inside the function *swapFun()*, we have used the *value at* operator to fetch the value available
at the address of both the variables. The two variables gets swapped inside the function. Because we're using the
address of both the variables, therefore the operation that has been done inside the function *swapFun()* effects
the variable's value throughout the program. That is, when we print the value of two variables inside the *main()*
function (after calling the function *swapFun()*), its value gets swapped.

To learn about Pointers or Functions in detail, then you can follow the separate tutorial on it.

#### Same Program in Other Languages

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