Converting char to int

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On Wednesday, 1 January 2014 at 06:21:05 UTC, Caeadas wrote:
> I hope you'll forgive my asking an overly easy question: I've
> been searching for an answer and having trouble finding one, and
> am getting frustrated.
>
> My issue is this: I'm trying to convert character types to
> integers using to!int from std.conv, and I'm getting, for
> example, '0'->48, '1'->49, etc. It seems like there should be a
> simple way around this, but it's eluding me.

Your code is working correctly. D's chars, for all values up to 
255, are the same as the ASCII character set. If you look in the 
ASCII table here: http://www.asciitable.com/ you will see that 
'0' corresponds to 48, and '1' corresponds to 49. The easiest 
solution that will fix your code is change to!int('0') and 
to!int('1') to to!int("0") and to!int("1"). It seems that for 
characters the to! function just returns its ASCII value, but it 
will definitely do what you want for strings. Strangely enough, 
it doesn't seem like there's a function to do convert a character 
to its numeric value in Phobos, but it's simple to implement.

int charToInt(char c)
{
     return (c >= 48 && c <= 57) ? cast(int)(c - 48) : -1;
}

void main()
{
     assert(charToInt('0') == 0);
     assert(charToInt('1') == 1);
     assert(charToInt('9') == 9);
     assert(charToInt('/') == -1);
     assert(charToInt(':') == -1);
}