Foreach with byte problems

Andrej Mitrovic none at none.none
Fri Feb 25 10:52:53 PST 2011


So I'd like to print all values storable in a byte in hex representation:

import std.stdio;
void main()
{
    int counter;
    foreach (byte index; byte.min..byte.max)
    {
        if (!(counter % 4))
            writeln();
        
        writef("%#.2x, ", index);
        counter++;
    }
}

If you run this, you'll realize that it doesn't print the final 0x7F. This is because in a foreach range literal (is that the correct term?), the left side is inclusive, but the right side isn't. 

Hence this will run the foreach from 0 to 9:
foreach (index; 0..10) { }

So I figured I'd just add a +1 at the end, but then I get an error:
    foreach (byte index; byte.min..byte.max+1)
    {
    }

Error: cannot implicitly convert expression (128) of type int to
byte. 

Of course 128 can't fit in a byte. But how am I supposed to print out the last value if the right hand side of a range literal is non-inclusive?

This behavior is kind of odd, don't you think?

byte.max is 127, but due to the way foreach works, the last value assigned to index is 126. If I was allowed to add +1 for RHS, the last value stored to index would be 127 due to the non-inclusive right side, which is completely legal. Yet DMD complains that I'm trying to store 128 to index.

I guess DMD first checks if the value on the RHS of the range literal can fit to a byte before it cuts one off due to the way range literals work. So how do I work around this?


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