Shared variable vs. global. The difference is that shared vars are shared between threads, bud globals don't.

shared.d

import std.stdio;
import core.thread;


shared int a=5;
int b=5;

void foo()
{writeln(" a=",a);writeln(" b=",b);}



void main()
{
    a=7;
    b=7;
	writeln("Main thread:");
	foo();
	auto thread = new Thread(&foo);
	writeln("Other thread:");
	thread.start();
	
	for (int i=0;i<1500; i++){;}//wait some
}