NetNews Usenet Archive 1992 #31/NN_1992_31.iso/spool/comp/lang/c/19099

Internet Message Format | 1992-12-31 | 2.3 KB

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From: [e-mail] (Chris Torek)
Newsgroups: comp.lang.c
Subject: Re: String function names
Date: 31 Dec 1992 23:41:02 GMT
Organization: Lawrence Berkeley Laboratory, Berkeley CA
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Message-ID: <[e-mail]>
References: <[e-mail]> <[e-mail]>
NNTP-Posting-Host: 128.3.112.15

Some time ago, in article <[e-mail]>
Ross Smith ([e-mail]) asked:
>>Out of curiosity, does anyone know the derivation of the names of the more
>>obscure string functions? Names like "strcat()" and "strlen()" are obvious
>>enough, but what on earth are "strcspn()", "strpbrk()", and "strspn()"
>>supposed to mean?

In article <[e-mail]> [e-mail]
(Timothy Kimball) writes:
>You got me.  And if you look on page 388 of Plauger,
>_The_C_Standard_Library_, you'll see that he's mystified by it, too-
>and he sits on the ANSI standards committees!

Someone else posted some guesses, but I think mine are closer. :-)

    strspn:    span (extend across) characters in a set, hence
        `STRing SPaN'
    strcspn: span characters in the complement of a set, hence
        `STRing Complement SPaN'

Strcoll() comes from `collate' (`assemble and arrange systematically'
or `compare').  Strpbrk() is something of a puzzle; the best I can come
up with is `point to break character' (from a set of break characters):
e.g., one might find white space for token-making using

    p = strpbrk(str, " \t\n");

Strstr() and strtok() are fairly stragihtforward (STRing subSTRing and
STRing TOKen).  Strxfrm() is `STRing transFoRM', with x replacing
`trans'.  Except for memmove, strcoll, strerror, and strxfrm---all ANSI
C inventions---the new functions entered C via System III UNIX, the
same people who brought you the wretched SysV IPC and shared memory.
That would explain both the peculiar set of operations (why both
strpbrk and strtok; why is strtok not reentrant; and why have strpbrk
and strcspn, which are complementary---strpbrk(a,b) is much like
a+strcspn(a,b)---without a complement for strspn?) and the inexplicable
names, all in one swell foop.
--
In-Real-Life: Chris Torek, Lawrence Berkeley Lab CSE/EE ([phone])
Berkeley, CA        Domain:    [e-mail]