Re: Numeric literals, take 3

[James Mastros]

On 11/27/2002 7:54 PM, Angel Faus wrote:

For example, the integer 30 can be written in base 16
in two equivalent ways:

   my $x = 16#1D;
   my $x = 16#1:14;

These two representations are incompatible, so writing
something like C<16#D:13> will generate a compile-time
error.

Ambiguity:
Is C<my $x = 16#14;> equivlent to the digit "14", base-sixteen, or is it equivlent to 0x14? (This has been noted before, but I don't think anybody has decided. My vote is 0x14, you should say my $x=16#0:14 if you want the other meaning.)

=section *** Bin/Hex/Oct shorthands

Since writing in binary, hexadecimal and octal is a moderately common operation, Perl offers a shorthand
for them:

0b0110 # bin
0c0123 # oct
0x00ff # hex
0x00fF # hex, == 0x00ff
0x00FF # hex, == 0x00ff

Loose specification:
You should probably note that while the digits are case-insensitive, the shorthand-radix-specifier is case-sensitive -- IE 0B0110 isn't 2:110, it's a syntax error (invalid digit in decimal literal).

Possible useful note:
Should we note that the C and perl5 notation of 0777 being octal is /not/ supported?

This won't work for bases greater than 36, so we
have too:

Grammar: I think this should be "so we also have:", or possibly "so we also have...".

In boolean context (see "Boolean Context") C<NaN> always
evaluates to false so.

Missing end-of-setance: "to false so those last two examples are false". (IE both !(NaN!=NaN) and !(NaN==NaN).)

Useful node:
We should probably note that Inf and NaN are case sensitive (or are they)?

NOTE: are we going to have +-Inf too?

Speculation: I don't think so. I don't think we're going to have -0 or +0 notations either (for underflow). Any parroters?

If you need to create typed C<Int> numbers without risking to lose precision, you should write them as a string literals:

I think Larry has mandated the oppisite -- that we Do The Right Thing with bigints automaticly -- IE that BigInt is a subclass of Int, with full automatic promotion. (I think this isn't going to be true of little-i int, though.)

-=- James Mastros