Source Code
// 14.i. Program to check whether a number is prime or not
// Arpan Das - CST 2nd Year (VOCLET)
#include <stdio.h>
//#include <conio.h>
//#include <stdlib.h>
void main () {
int i, num, flag=1; // 1 = prime
//system("cls");
//clrscr();
printf("\t\t..:: check whether a number is prime or not ::..\n\n");
printf("pleae enter any number: ");
scanf("%d", &num);
for (i=2; i<=num/2; i++) {
if (num%i == 0) {
flag = 0;
break;
}
}
if (flag==1)
printf("%d is a prime number.", num);
else
printf("%d is not a prime number.", num);
//getch();
}
Output
..:: check whether a number is prime or not ::..
pleae enter any number: 15
15 is not a prime number.
..:: check whether a number is prime or not ::..
pleae enter any number: 17
17 is a prime number.