Check prime number

#include<stdio.h>
#include<conio.h>
int main()
{
int a,b,c;
a=1;
b=2;
printf("enter values\n");
scanf("%d",&c);
while(b<=c/2){
if(c%b==0)
a=0;
b++;
}
if(a==0)
printf("not prime number");
else
printf("prime number");
getch();
}