NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/lang/c-part1/5852

Internet Message Format | 1996-08-05 | 2.6 KB

Path: mail2news.demon.co.uk!genesis.demon.co.uk
From: Lawrence Kirby <[e-mail]>
Newsgroups: comp.lang.c
Subject: Re: Easiest way to center a string?
Date: Wed, 21 Feb 96 15:08:59 GMT
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In article <[e-mail]>
           [e-mail] "The Amorphous Mass" writes:

>On 20 Feb 1996, Tanmoy Bhattacharya wrote:
>
>> In article Amorphous Mass <[e-mail]> writes:
>> <snip>
>>      That's equivalent to strlen(String + -LineLen), which is in turn
>>    equivalent to strlen(String[-LineLen]), and the expression String[-80] is
>>    portable only in the sense that its behavior is undefined on all
>>    platforms. :)
>>
>> Sorry there is no trigraph for `&': so if that key is broken, you just
>> have to get it fixed :-)
>
>???  Works fine.  My tilde key is broken though, which makes UNIX a real
>pain.

String + -LineLen is equivalent to &String[-LineLen] except where
String[-LineLen] tries to access the element one past the end of the
array.

>>      If you meant (strlen(String) - LineLen) / 2 then you will get a
>>    negative length specifier for any string with fewer than LineLen
>>    characters.  If you meant (LineLen - strlen(String) / 2, then your
>>
>> strlen returns size_t which is guaranteed unsigned. (I am assuming
>> LineLen is not long.)
>
>  Right, but strlen(String) would be 12, minus LineLen which is 80, which
>is -68,

No, it is UINT_MAX (or ULONG_MAX, etc.)-68 (assuming the size_t value doesn't
get promoted to int or long).

>divided by two is -34, which is the number passed as a width
>specifier to printf().  I don't think printf("%*s", -34, "hello, world);
>is worth much. :)

Probably more than (UINT_MAX-68)/2 ! :-) Also with fixed string -------^

>  I guess I didn't say that at all clearly the first time.  Is it clearer
>now, or am I _completely_ brain-dead?

You don't provide much in the way of choice there! :-))

Did anybody mention:

  (int)((strlen(String) + LineLen) / 2) ?

You just have to decide what to do if the string is longer than the line.

--
-----------------------------------------
Lawrence Kirby | [e-mail]
Wilts, England | [e-mail]
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