Cheaking prime number code in C++

#include<iostream.h>
 #include<math.h>
 void main()
 {
 int num,count=2;
 double sqnum;
 cout<<"enter the number you want to check\n";
 cin>>num;
 sqnum=sqrt(num);
 while(count<=sqnum)
 {
 if(num%count==0)
 {
 cout<<"the number you enter is not a prime number\n";
 break;
 }
 else
 {
 count++;
 }
 }
 if(num%count!=0)
 {
 cout<<"the number is a prime number\n";
 }
 }