Subj : Re: string comparison
To   : borland.public.cpp.borlandcpp
From : maeder@glue.ch (Thomas Maeder [TeamB])
Date : Mon Nov 24 2003 09:31 pm

"Base8" <Base8@base8.com> writes:

> Is there a simple way to do this?

Assuming that passedstring points to a zero terminated string, this will do
what you are looking for.

unsigned char const c(passedstring[0]);
return std::isalpha(c) ? 0 : -1;

std::isalpha is declared in the Standard header <cctype>. It takes an argument
of type int, which has to be either equal to EOF or have an unsigned char
value. I returns a value !=0 if c represents a letter in the encoding used
by the program.


I don't understand the remainder of your code, and others have already
pointed out errors in it. The following problem hasn't:

> newstring = new char[ sizeof(passedstring + 1 )] ;
> assert( newstring != 0 ) ;

This test is moot. This new expression will *never* evaluate to 0. If the
allocation request can't be served, the new expression causes an exception
of type std::bad_alloc to be thrown.


Do not rely on the letters being encoded contiguously, i.e.

   'a'<=passedstring[0] && passedstring[0]<='z'
|| 'A'<=passedstring[0] && passedstring[0]<='Z'

is *not* a good idea. First because you can't even portably assume that this
will catch all the letters from 'a' to 'z', and second because you'll very
probably miss the other letters (Umlauts, accented letters etc.).

.