Write a c program to check whether a no is prime or not?

Answer 1

#include<stdio.h> #include<conio.h> int i=1, count=0,n; clrscr(); printf("Enter Any Number"); scanf("%d", &n); while(i<n) if(n%i==0) { count++; i++; } if(count==2) printf("Given Number is Prime"); else printf("Given Number is not Prime"); getch(); }

Answer 2

#include<stdio.h> #include<conio.h> void main() { int num,i=2; print ("\n enter any number"); scanf("%d",&num); while(i<num) { if(num%i==0) { printf("\n number is not prime"); break; } else { i++; } getch(); }

Answer 3

#include<iostream.h> #include<conio.h>

int main()

{

clrscr();

cout<<"PROGRAM TO CHECK IF THE NUMBER IS PRIME OR NOT:"<<endl;

cout<<"Enter a number:";

int n;

cin>>n;

for(int i=2;i<n;i++)

{

if(n%i==0)

{

cout<<"THE NUMBER IS NOT PRIME"<<endl;

}

}

if(i==n)

{

cout<<"THE NUMBER IS PRIME"<<endl;

}

else

{

exit(1);

}

getch();

return 0;

}

Note: the exit(1) statment needs protype

and on not prime numbers it execute the full loop and print the result like this

enter the number

n=6

the number is not prime

the number is not prime

the number is prime

instead of it try this code with a little modification .

i aknowledge your work.

#include<iostream.h>

#include<conio.h>

void main()

{

clrscr();

cout<<"PROGRAM TO CHECK IF THE NUMBER IS PRIME OR NOT:"<<endl;

cout<<"Enter a number:";

int n;

cin>>n;

for(int i=2;i<n;i++)

{

if(n%i==0)

{

cout<<"THE NUMBER IS NOT PRIME"<<endl;

goto g1;

}

}

if(i==n)

{

cout<<"THE NUMBER IS PRIME"<<endl;

}

g1:

getch();

}

Answer 4

bool isPrime(int n)

{

int i=2; //1 is not a prime so start from 2

//run a loop to check if any number divides that number

//we are checking all the numbers below the given number

while(i < n)

{

if(n % i == 0) //if any number below a given number divides it then not prime

return false;

i++;

}

return true; //if all number is checked fior divisibility and no number divides it its a prime

}

Answer 5

Linux or Windows or any other platform makes no difference. All you need is the following user-defined function:

bool isprime(unsigned long long p)

{

if( p<=1 ( p>2 && p%2==0 ))

return( false );

unsigned long long max = (unsigned long long)sqrt(( double ) p ) + 1;

for( unsigned long long i=3; i<=max; i+=2 )

if( p%i==0 )

return( false );

return( true );

}

Answer 6

/*this is a program to check wether a no is prime or composite*/

#include<stdio.h>

#include<conio.h>

void main()

{

int no,i;

clrscr();

printf(" Enter the Number U want to check:");

scanf("%d",&no);

i=2;

while(i<=no-1)

{

if(no%i==0)

{

printf(" %d is composite",no );

break;

}

i=i+1;

}

if(no==i)

printf("%d is a Prime number",no);

getch();

}