Swap two numbers without Using third variable in C

In this program we will swap two numbers without using third variable. Lets understand common ways to swap two numbers without using third variable:

1. By + and -
2. By * and /

First we will learn swapping of two numbers

Program 1: Using Third Variable 

Let's write a program in C to swap two numbers using third variable.

2. #include <stdio.h>
3. int main()
4. {
5.       double firstNumber, secondNumber, temporaryVariable;
6. 
   
7.       printf("Enter first number: ");
8.       scanf("%lf", &firstNumber);
9. 
   
10.       printf("Enter second number: ");
11.       scanf("%lf",&secondNumber);
12. 
    
13.       // Value of firstNumber is assigned to temporaryVariable
14.       temporaryVariable = firstNumber;
15. 
    
16.       // Value of secondNumber is assigned to firstNumber
17.       firstNumber = secondNumber;
18. 
    
19.       // Value of temporaryVariable (which contains the initial value of firstNumber) is assigned to secondNumber
20.       secondNumber = temporaryVariable;
21. 
    
22.       printf("\nAfter swapping, firstNumber = %.2lf\n", firstNumber);
23.       printf("After swapping, secondNumber = %.2lf", secondNumber);
24. 
    
25.       return 0;
26. }

Output:

Before swap a=10 b=20
After swap a=20 b=10

Program 1: Using + and -

Let's write a program in C to swap two numbers without using third variable.

1. #include<stdio.h>  
2. #include<conio.h>  
3. main()  
4. {  
5. int a=10, b=20;    
6. clrscr();    
7. printf("Before swap a=%d b=%d",a,b);    
8.   
9. a=a+b;//a=30 (10+20)  
10. b=a-b;//b=10 (30-20)  
11. a=a-b;//a=20 (30-10)  
12.   
13. printf("\nAfter swap a=%d b=%d",a,b);  
14. getch();  
15. }  

Output:

Before swap a=10 b=20
After swap a=20 b=10

Program 2: Using * and /

Let's see another example to swap two numbers using * and /.

1. #include<stdio.h>  
2. #include<conio.h>  
3. main()  
4. {  
5. int a=10, b=20;    
6. clrscr();    
7. printf("Before swap a=%d b=%d",a,b);    
8.   
9. a=a*b;//a=200 (10*20)  
10. b=a/b;//b=10 (200/20)  
11. a=a/b;//a=20 (200/10)  
12.   
13. printf("\nAfter swap a=%d b=%d",a,b);   
14. getch();  
15. }  

Output:

Before swap a=10 b=20
After swap a=20 b=10

reverse number Program in C

C Program to reverse number

In this Program we will using loop and arithmetic operators and make a Program to reverse Integer Numbers. First, we will getting number as input from the user and reversing that number.

Lets Understand Program Steps

1. #include<stdio.h>  
2. #include<conio.h>  
3. main()  
4. {  
5. int n, reverse=0, rem;  
6. clrscr();  
7. printf("Enter a number: ");  
8.   scanf("%d", &n);  
9.   while(n!=0)  
10.   {  
11.      rem=n%10;  
12.      reverse=reverse*10+rem;  
13.      n/=10;  
14.   }  
15.   printf("Reversed Number: %d",reverse);  
16. getch();  
17. }  

Output:

Enter a number: 123
Reversed Number: 321

Sum of digits program in C

Sum of digits program in C With Example

C program to sum each digit: Let's Make a program in C language to the sum of digits program with the help of loop and mathematical operation.

Steps to design algorithm sum of Integers

To get sum of each digits by c program, use the following algorithm:

• Step 1: Take number by user as Input
• Step 2: Get the modulus/remainder of the number
• Step 3: sum the remainder of the number
• Step 4: Divide the number by 10
• Step 5: Repeat the step 2 while number is greater than 0.

Let's see the sum of digits program in C.

1. #include<stdio.h>  
2. #include<conio.h>  
3. void main()  
4. {  
5. int n,sum=0,m;  
6. clrscr();  
7. printf("Enter a number:");  
8. scanf("%d",&n);  
9. while(n>0)  
10. {  
11. m=n%10;  
12. sum=sum+m;  
13. n=n/10;  
14. }  
15. printf("Sum is=%d",sum);  
16. getch();  
17. }     

Output:

Enter a number:654
Sum is=15

Enter a number:123
Sum is=6

Armstrong Number in C

Armstrong Number in C Language

Before writing a program in C language to check whether the number is Armstrong or not, First we will understand what is Armstrong number.

What is the Armstrong Number

Armstrong number is a number that is equal to the sum of cubes of its digits. For example 0, 1, 153, 370, 371 and 407 are the Armstrong numbers.

Note: there are six Armstrong numbers in the range of 0 and 999.

Armstrong number 1: 0
Armstrong number 2: 1
Armstrong number 3: 153
Armstrong number 4: 370
Armstrong number 5: 371
Armstrong number 6: 407

Let's try to understand why 153 is an Armstrong number.

Let's try to understand why 371 is an Armstrong number.

Let's see the c program to check any number provided by user is Armstrong Number or not

Output:

enter the number=153
armstrong number

enter the number=5
not armstrong number