Check whether a given number is a prime or not | Prime number program in C, C++ and Java

Check whether a given number is a prime or not | Prime number program in C, C++ and Java

The prime number program in C is discussed below in various methods. You can check if a given number is prime or not


Check whether a given number is a prime or not

  • Using for loop
  • Using functions
  • Using pointers and
  • Using recursion


A number is said to be prime if it is divisible by 1 and itself. It should not have any other divisors.


Check whether a given number is a prime or not

Prime number programs using various methods


Using for loop

#include<stdio.h>nint main()n{nint n,i;nprintf(“nEnter the number : “);nscanf(“%d”,&n);nfor(i = 2; i <= n/2; i++)n{nif(n % i ==0)n{nbreak;n}n}nif(i > n/2)nprintf(“n%d is a Prime Numbern”,n);nelsenprintf(“n%d is not a Prime Numbern”, n);nreturn 0;n}n



Check whether a given number is a prime or not

Using pointers

#include<stdio.h>nint is_prime_number(int *p)n{nint i;nfor(i = 2; i <= *p/2; i++)n{nif(*p % i ==0)n{nbreak;n}n}nif(i > *p/2)nprintf(“n%d is a Prime Numbern”,*p);nelsenprintf(“n%d is not a Prime Numbern”, *p);n}nint main()n{nint n,i;nprintf(“nEnter the number : “);nscanf(“%d”,&n);nint *p = &n;nis_prime_number(p);nreturn 0;n}n


Using functions

#include<stdio.h>nint is_prime_number(int n)n{nint i;nfor(i = 2; i <= n/2; i++)n{nif(n % i ==0)n{nbreak;n}n}nif(i > n/2)nprintf(“n%d is a Prime Numbern”,n);nelsenprintf(“n%d is not a Prime Numbern”, n);n}nint main()n{nint n,i;nprintf(“nEnter the number : “);nscanf(“%d”,&n);nis_prime_number(n);nreturn 0;n}n


Using recursion

#include<stdio.h>nint is_prime_number(int num, int i)n{nif(num < 2)n{nprintf(“nEnter numbers greater than 1n”);nexit(0);n}nif (i == 1)n{nreturn 1;n}nelsen{nif (num % i == 0)n{nreturn 0;n}nelsen{nreturn is_prime_number(num, i – 1);n}n}n}nint main()n{nint n, flag;nprintf(“Enter a number: “);nscanf(“%d”, &n);nflag = is_prime_number(n, n / 2);nif (flag == 1)n{nprintf(“n%d is a prime numbern”, n);n}nelsen{nprintf(“n%d is not a prime numbern”, n);n}nreturn 0;n}n



Check whether a given number is a prime or not

Using command line

The given number N, a positive integer, will be passed to the program using the first command line parameter. If it is a prime number the output should be the square root of the number up to 2 decimal point precision, If it is not a prime number then print 0.00 to stdout.

#include<stdio.h>n#include<math.h>n#include<stdlib.h>nint main(int a, char *b[])n{nint number,i,flag = 1;nscanf("%d",&number);nnnfor(i=2; i<number; i++)n{nif(number%i == 0)n{nflag = 0;nbreak;n}n}nif(flag == 1)nprintf("%.2f",sqrt(number));nelsenprintf("0.00");nreturn 0;n}n

Output:

prime number program in c


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Check whether a given number is a prime or not

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