int c = 0;

​

int a()

{

    return c++;

}

​

int b()

{

    return c--;

}

​

void main()

{

    import std.conv : to;

    import std.stdio : writeln;

    writeln(to!string(a) ~ to!string(b));

}

​

/*

The correct answer is maybe "10", but also "-10".

​

Why is that?

​

There is no guarantee that a is executed before b.

​

This is of course a common behavior from even C++ as the following would give the same result:

​

```

std::cout << a() << b();

```

*/