#include<bits/stdc++.h> cannot work

#include <iostream>

#include <bits/stdc++.h>

int main() {
    std::cout << "Hello, World!" << std::endl;
    std::cout << sqrt(25);
    return 0;
}

Hello, World!
5
Process finished with exit code 0

It is working on my system, it is a trial version. What compiler are you using ?

I did not add anything, just the include and the sqrt line. It was just a simple project>new.

Hi Hemalhemal787 !

bits/stdc++.h is a non-standard header file of GNU C++ library. So, if you try to compile your code with some compiler other than GCC it might fail; e.g. MSVC does not have this header.