Does your Compiler not find the errors ?
There are several of them ...
For example
int main();
No time to comment them all ...
Take a look at this and start reading a book about C++.
#include <iostream>
using namespace std;
int main()
{
int netsalary;
int basicsalary;
int bonus;
int tax;
cout << "please enter the basic salary: ";
cin >> basicsalary;
cout << " and the bonus: ";
cin >> bonus;
if( basicsalary<=1000 )
tax=basicsalary*10/100;
else
tax=basicsalary*20/100;
netsalary=basicsalary+bonus-tax;
cout<<netsalary;
return 0;
}
Do you really want calculation with int result ?