crack-me cannot compile because "system" was not declared in the scope

[nitrocode]

I'm on linux and had to also include cstdlib to compile crack-me in the first tutorial

✗ g++ crack-me.cpp -o crack-me
crack-me.cpp: In function ‘void secret()’:
crack-me.cpp:17:23: error: ‘system’ was not declared in this scope
    system("uname -a\n");

Added and it compiles correctly with g++ 5.4.0

#include <cstdlib>

Maybe my g++ version is too old.

[roussov]

hi @nitrocode
n this case, the reported “error” is entirely expected from the C++ side.

You have the following code:

void secret() {
    system("uname -a\n");
}

And the compiler reports:

error: ‘system’ was not declared in this scope

In C++, system is declared in (or in C, in <stdlib.h>).
Without that include, the compiler has no declaration for the function, which leads to the error.

The fix in the code is:

#include <cstdlib>   // or <stdlib.h>, but <cstdlib> is the recommended C++ header.

void secret() {
    std::system("uname -a\n");  // std::system is preferable for cleanliness, but calling system(...) without the namespace also works.
}

The fact that it compiles after adding:

#include <cstdlib>

So this behavior is completely normal; it’s not really a g++ bug, even with version 5.4.0.