Prime Number is c:

A natural number greater than one has not any other divisors except 1 and itself. In other word we can say which has only two divisors 1 and number itself. For example: 5

Their divisors are 1 and 5.

Note: 2 is only even prime number.



Logic for prime number in cWe will take a loop and divide number from 2 to number/2. If the number is not divisible by any of the numbers then we will print it as prime number.


Example of prime numbers : 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199 etc.

1. C program to find given number is prime or not

#include<stdio.h>

int main(){

    int num,i,count=0;

    printf("Enter a number: ");

    scanf("%d",&num);

    for(i=2;i<=num/2;i++)

    {

        if(num%i==0)

        {

            count++;

            break;

        }

    }

   if(count==0 && num!= 1)

        printf("%d is a prime number",num);

   else

      printf("%d is not a prime number",num);

   return 0;

}

Sample output:

Enter a number: 5

5 is a prime number

2.C program for prime numbers between 1 to 100

#include<stdio.h>

int main()

{

    int num,i,count;

  

    for(num = 1;num<=100;num++)

    {

         count = 0;

         for(i=2;i<=num/2;i++)

         {

             if(num%i==0)

             {

                 count++;

                 break;

             }

         }        

         if(count==0 && num!= 1)

             printf("%d ",num);

    }  

   return 0;

}

Output:

2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97

3. C program to find prime numbers using while loop

int main()

{

   int num,i,count,min,max;

printf("Enter min range: ");

    scanf("%d",&min);

    printf("Enter max range: ");

    scanf("%d",&max);

    num = min;

    while(num<=max)

    {

         count = 0;

         i=2;

         while(i<=num/2)

         {

             if(num%i==0)

             {

                 count++;

                 break;

             }

             i++;

        }

        

         if(count==0 && num!= 1)

             printf("%d ",num);

         num++;

    }  

   return 0;

}

Sample output:

Enter min range: 50

Enter max range: 100

53 59 61 67 71 73 79 83 89 97

4. C program to find sum of prime numbers

#include<stdio.h>

int main()

{

    int num,i,count,min,max,sum=0;

     printf("Enter min range: ");

     scanf("%d",&min);

    printf("Enter max range: ");

    scanf("%d",&max);

    for(num = min;num<=max;num++)

    {

         count = 0;

         for(i=2;i<=num/2;i++)

         {

             if(num%i==0)

             {

                 count++;

                 break;

             }

        }        

         if(count==0 && num!= 1)

             sum = sum + num;

    }

    printf("Sum of prime numbers is: %d ",sum);  

   return 0;

}

Sample output:

Enter min range: 50

Enter max range: 100

Sum of prime numbers is: 732

Unknown Monday, March 09, 2015

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About Author

SK Sitaram is a computer engineering. He has completed Advance Diploma in Software Engineering.
He is Founder and Developer of C Programming Simply. He loves researching in the IT field.
This is a part time blogger, Like a bathroom singer(:P) and He is Student of Jaipur National University. You can follow him in Twitter and find him in Facebook or Email him. Byeee (:P)

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