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Re: lynx-dev type of isdigit etc. (was: Relatively mild dev13 build prob


From: T.E.Dickey
Subject: Re: lynx-dev type of isdigit etc. (was: Relatively mild dev13 build problems)
Date: Sun, 31 Oct 1999 13:53:53 -0500 (EST)

> FYI, a comment form GNU libc's ctype.h regarding that library's 
> implementation: 
>  
> (The first sentence's "These" refers to macros that are used in the 
> expansion of is*(), to*().) 
>  
>    These point into arrays of 384, so they can be indexed by any `unsigned 
>    char' value [0,255]; by EOF (-1); or by any `signed char' value 
>    [-128,-1).  ISO C requires that the ctype functions work for `unsigned 
>    char' values and for EOF; we also support negative `signed char' values 

indeed (more common is to simply dump core when there's inadvertant sign-
extension)

>    for broken old programs.  The case conversion arrays are of `int's 
>    rather than `unsigned char's because tolower (EOF) must be EOF, which 
>    doesn't fit into an `unsigned char'.  But today more important is that 
>    the arrays are also used for multi-byte character sets.  */ 

for that, 384 entries won't work...
  
> So it accepts negative values only to cater for improper use. 
>  
>    Klaus 


-- 
Thomas E. Dickey
address@hidden
http://www.clark.net/pub/dickey

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