SPUG:m,n -- why?

Tim Maher tim at consultix-inc.com
Sat Mar 15 12:14:43 CST 2003


On Fri, Mar 14, 2003 at 11:24:15PM -0800, Michael R. Wolf wrote:
> 
> Does anyone know the historical roots of "n" and "m" for "min" and
> "max" in the regex quantifiers?  I can never get a mnemonic for which
> is which.  (Of course, the min is to the left of the max.)  Perhaps if
> I know it's roots, I'll remember.

That comes from the good-old ed editor, which provided the same
metacharacters.  M comes first, and then n.  I believe they were
chosen for Fortranish reasons; i, j, and k were always the the first
three (automatically understood as) integer variables one would
use in a program, so to mark these placeholders as integers but
special in some way, i.e., not the conventional loop indices i,j,
or k, Brian Kernighan started with m.  M conveniently stands for
minimum too, and N is just the next sequential letter (no mnemonic).
Go figure . . .

> That is (n,m) = (0,7) in this snippet:
> 
>     if ($fruit =~ /b(an){0,7}a/) {
>         print "You've got an modular banana\n";
>     }
> 
> 
> -- 
> Michael R. Wolf
>     All mammals learn by playing!
>         MichaelRunningWolf at att.net
> 
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