Hi!
23-Июл-2005 05:34 [EMAIL PROTECTED] (Kenneth J. Davis) wrote to
[email protected]:
>> if (rest [1] != ':' || rest [2] != '\0')
>> KD> + drive = toupper(rest[0]) - 'A';
>> Here not checked, that rest [0] is a letter.
KJD> true, but according to TC docs, toupper() supports EOF (-1 I believe) to
KJD> 255 and any non-lowercase item is returned unchanged; so no check
No, I mean something like:
if (!isletter (rest [0]) || rest [1] != ':' || rest [2] != '\0')
>---^^^^^^^^^^^^^^^^^^^^^^^
KJD> should be necessary. I suppose we could explicitly check for a letter
KJD> argument and return syntax error if not (since not a drive usually),
KJD> then change to use _toupper macro or even straight bit manipulation
KJD> (anding off bit 5 I think).
______________O\_/_________________________________\_/O______________
/* !!! Fast ASCII tolower/toupper !!! */
#define _lower(ch) ((ch) | 0x20)
#define _dolower(var) ((var) |= 0x20)
#define _upper(ch) ((ch) & ~0x20)
#define _doupper(var) ((var) &= ~0x20)
_____________________________________________________________________
O/~\ /~\O
Thus:
char ch = rest [0]; _doupper (ch);
if (ch < 'A' || ch > 'Z') ...not a letter...
PS: Just to remember how to fast upper/lowercase: in 16x16 ASCII table first
two columns (0x00-0x1F) are control codes, two second columns (0x20-0x3F) -
punctuations, next two columns (0x40-0x5F) of upcase and then two columns
(0x60-0x7F) of lowercase. Thus, clearing bit 0x20, is required and enough to
convert lower case into upcase, remain upcase in upcase. All other codes not
fall into letters.
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