Array slicing

[Heinz]

Hi, i'm trying to slice an array of chars and print it to the screen but it
doesn't seems to work, here's the code:

/////////////////////////////////////
import std.string;

alias char[] string;

int main(char[][] args)
{
    printf("hello world\n");
	string hw = "Hello_World";
	printf(cast(char*)hw[0 .. 5]);
    return 0;
}

/////////////////////////////////////

What could be wrong? it just prints to the output "Hello_World".

Heinz