NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/lang/c-part2/10544

Internet Message Format | 1996-08-05 | 2.7 KB

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From: Lawrence Kirby <[e-mail]>
Newsgroups: comp.lang.c
Subject: Re: Converting Strings to Upper Case
Date: Mon, 18 Mar 96 16:14:03 GMT
Organization: none
Message-ID: <[e-mail]>
References: <4ifra6$[e-mail]> <[e-mail]> <4ii1nh$[e-mail]>
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In article <4ii1nh$[e-mail]>
           [e-mail] "Bill McCarthy" writes:

>In <[e-mail]>, [e-mail] (Doug & Rose Miller) writes:
>>[e-mail] () wrote:
>>+Hi,
>>+
>>+
>>+and the string would be modified.  I just can't seem to wrap my head around
>>+the best way that I know is better than writing a for loop to check each
>>+element in the array?
>>+
>>+I apologize if this in the FAQ;  I am still going thorugh it.  Any help
>>+would be greatly appreciated.
>>+
>>+Eric Woodward.
>>[e-mail].
>>+
>>
>>
>>#include <stdio.h>
>>
>>void main (void) {
>
>Oh, please!  Read the FAQ to avoid posting crap like this.
>
>>char    test[] = "aBcDeFgHiJkLmNoPqRsTuVwXyZ";
>>char    *p;
>>
>>printf ("%s\n", &test);
>
>&test ???  How about just test?
>
>>for (p = test; *p; *p++)
>
>And what do you think you are accomplishing with *p++ that p++ or ++p
>wouldn't do???
>
>>    if (isalpha(*p)) *p ^= 0x20;  /* for ascii machines e.g. PC; use 0x40 for
> ebcdic machines e.g. IBM mainframe */

You could make the code itself more portable (and IMHO clearer) by writing
this as:

      if (isalpha(*p)) *p ^= 'A' ^ 'a';

This still isn't guaranteed by the C language itself but it works for the
character sets you are likely to encounter in the "C" locale. Whether such a
hack is preferable over the 'correct' version below is questionable
and depends on the use to which it is being applied.

      *p = isupper(*p) ? tolower(*p) : toupper(*p);

>isalpha() has not been declared.  It takes an int and *p may be a signed
>char, how about *(unsigned char *)p.

It is certainly tempting to make p unsigned char *.

> Also, your code is toggling between
>upper and lower case.

To be fair that looked like what was asked:

>>+I need to write a function to convert a string containg upper or lower case
>>+characters to the opposite case.  Something like:

However the declarations suggest otherwise:

>>+  void libConvertUpperCase(char *str);        and
>>+  void libConvertLowerCase(char *str);

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