Prime Number Program in C – C Program for Prime Number

Prime number program in c along with the output is given below.

About Prime Numbers

Any natural number like 1, 2, 3, etc. is called a prime or a prime number if it is greater than 1 and can only be divided by 1 and the number itself.

For example,
2, 3, 5, 7, 11, 13, 17, 19, 23, 29,…, and so on

It should be noted that the natural numbers greater than 1 that are not prime numbers are called composite.

Prime Number Program in C – Program 1

The below c program for prime number takes an integer as input, and checks whether the input number is a prime number or not.

#include<stdio.h>
void main()
{
    int x,i,flag=0;
    printf("Enter number to be checked whether it is prime or notn");
    scanf("%d",&x);
    if(x>0)
    {
        for(i=2; i<=x/2; i++)
        {
            if(x%i==0)
            {
                flag=1;
                break;
            }
        }
        if(flag==0 && x!=1)
            printf("Number is primen");
        else
            printf("Number is not primen");
    }
    else
        printf("Please enter number greater than 0n");

    getch();
}

Output

Prime Number Program in C – Program 2

The below c program for prime number prints the total number of prime numbers provided as an input by the user.

#include<stdio.h>

void main()
{
    int n,count=1,i,flag=0;
    printf("Enter total number of prime numbers to be generatedn");
    scanf("%d",&n);
    printf("List of prime numbersn");
    for(i=2; count<=n; i++)
    {
        flag=prime(i);
        if(flag==1)
        {
            printf("%dn",i);
            count++;

        }
    }
    getch();
}
int prime(int x)
{
    int j;
    for(j=2; j<=x/2; j++)
    {
        if(x%j==0)
        {
            return 0;
            break;
        }

    }
    if(j>x/2)
        return 1;
}

Prime Number Program in C – Program 3

The below c program for prime number prints all the prime numbers between a range as mentioned by the user.

#include<stdio.h>

void main()
{
    int start,end,i,flag=0;
    printf("Enter range between which prime numbers are to be generatedn");
    scanf("%d%d",&start,&end);
    printf("List of prime numbers between %d and %dn",start,end);
    for(i=start; i<=end; i++)
    {
        flag=prime(i);
        if(flag==1 && i!=1)
            printf("%dn",i);
    }
    getch();
}
int prime(int x)
{
    int j;
    for(j=2; j<=x/2; j++)
    {
        if(x%j==0)
        {
            return 0;
            break;
        }

    }
    if(j>x/2)
        return 1;
}

Output

2 Responses

  1. sowji
    sowji September 19, 2012 at 10:59 am | | Reply

    program input give little more easy .programs which are give are difficult to understand.

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