prevents the screen from closing after the program is finished
this is small but incredibly useful, especially if your IDE doesn't have have support for this
example:
#include <iostream>
int main()
{
std::cout << "hello world!";
halt();
return 0;
}
#ifndef HALT_H_
#define HALT_H_ 1
#ifndef _GLIBCXX_IOSTREAM
#include <iostream>
#endif
struct halt{~halt(){std::cin.ignore();}};
#endif