44 lines
828 B
C
44 lines
828 B
C
/* Prime number - Program to check whether a given number is prime or not */
|
|
|
|
/* Assume 2 is a prime number but 0 and 1 are not */
|
|
|
|
#include <stdio.h>
|
|
#include <conio.h>
|
|
|
|
void main()
|
|
{
|
|
int p,d, flag ;
|
|
clrscr() ;
|
|
printf("Enter a number: ") ;
|
|
scanf("%d", &p) ;
|
|
flag=1 ; /* Assuming p is prime */
|
|
for(d=2 ; d<=p-1 ; d++) /* d<=p/2 is also correct */
|
|
if(p%d==0) /* True if number is not prime */
|
|
{
|
|
flag=0 ;
|
|
break ; /* Loop terminates if p is not prime */
|
|
}
|
|
if(flag==0 || p==1 || p==0 )
|
|
printf("%d is not prime", p) ;
|
|
else
|
|
printf("%d is prime", p) ;
|
|
getch() ;
|
|
}
|
|
|
|
/*
|
|
Output 1:
|
|
|
|
Enter a number: 1
|
|
1 is not prime
|
|
|
|
Output 2:
|
|
|
|
Enter a number: 7
|
|
7 is prime
|
|
|
|
Output 3:
|
|
|
|
Enter a number: 9
|
|
9 is not prime
|
|
*/
|