check the given no is prime or not

void main()
{
int num,i,count=0;
clrscr();
printf("\nEnter a number:");
scanf("%d",&num);
for(i=1;i<=num;i++)
{
if(num%i==0)
count++;
}
if(count==2)
printf("%d is a prime number",num);
else
printf("%d is not a prime number",num);
getch();
}