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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