Prime Number program in C language With Example

Prime Number program in C language

Prime number: Prime number is a whole number that is larger than one (1) and divided by 1 or itself.

 In other words, 

prime number has only two Factor that are 1 and itself. For example 2, 3, 5, 7, 11, 13, 17, 19, 23.... are the prime numbers.

Note: Zero (0) and 1 are not considered as prime numbers. Two (2) is the only one even prime number because all the Even numbers can be divided by 2.

Let's see how to write prime number program in C language and Execution of C Program. In this c program, we will get an input from the user and check This the number is prime or not.

1. #include<stdio.h>  
2. #include<conio.h>  
3. void main()  
4. {  
5. int n,i,m=0,flag=0;  
6. clrscr();  
7. printf("Enter the number to check prime:");  
8. scanf("%d",&n);  
9. m=n/2;  
10. for(i=2;i<=m;i++)  
11. {  
12. if(n%i==0)  
13. {  
14. printf("Number is not prime");  
15. flag=1;  
16. break;  
17. }  
18. }  
19. if(flag==0)  
20. printf("Number is prime");  
21. getch();  
22. }   

Output:

Enter the number to check prime:56
Number is not prime

Enter the number to check prime:23
Number is prime

Fibonacci Series in C language with Example

Fibonacci Series in C

Fibonacci Series: Fibonacci sequence or Fibonacci Series is a series where the next number is the sum of pervious two numbers. The first two terms of the Fibonacci sequence is 0 followed by 1. 

For Example

The Fibonacci sequence or Fibonacci Series: 0, 1, 1, 2, 3, 5, 8, 13, 21 etc. The first two numbers of fibonacci series are 0 and 1.

Lets understan using This Image:

There are two ways to write the fibonacci series program:

• Fibonacci Series without recursion
• Fibonacci Series using recursion

Fibonacci Series in C without recursion

Let's see the fibonacci series program in c without recursion.

1. #include<stdio.h>  
2. #include<conio.h>  
3. void main()  
4. {  
5.  int n1=0,n2=1,n3,i,number;  
6.  clrscr();  
7.  printf("Enter the number of elements:");  
8.  scanf("%d",&number);  
9.  printf("\n%d %d",n1,n2);//printing 0 and 1  
10.   
11.  for(i=2;i<number;++i)//loop starts from 2 because 0 and 1 are already printed  
12.  {  
13.   n3=n1+n2;  
14.   printf(" %d",n3);  
15.   n1=n2;  
16.   n2=n3;  
17.  }  
18. getch();  
19. }  

Output:

Enter the number of elements:15
0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 

Fibonacci Series using recursion in C

Let's see the fibonacci series program in c using recursion.

1. #include<stdio.h>  
2. #include<conio.h>  
3. void printFibonacci(int n){  
4.     static int n1=0,n2=1,n3;  
5.     if(n>0){  
6.          n3 = n1 + n2;  
7.          n1 = n2;  
8.          n2 = n3;  
9.          printf("%d ",n3);  
10.          printFibonacci(n-1);  
11.     }  
12. }  
13. void main(){  
14.     int n;  
15.     clrscr();  
16.     printf("Enter the number of elements: ");  
17.     scanf("%d",&n);  
18.   
19.     printf("Fibonacci Series: ");  
20.     printf("%d %d ",0,1);  
21.     printFibonacci(n-2);//n-2 because 2 numbers are already printed  
22.   
23.     getch();  
24. }  

Output:

Enter the number of elements:15
0 1 1 2 3 5 8 13 21 34 55 89 144 233 377