Re: ctype & cctype in transform
On 2008-04-24 10:15:36 -0400, Taras_96 <taras.di@gmail.com> said:
A poster at http://bytes.com/forum/thread60652.html implies that using
strtoupper in transform doesn't work because ctype.h may define
strtoupper as a macro:
"The problem is that most implementations of the standard C <ctype.h>
header define functions like toupper/tolower/etc as macros. To make it
work in STL algorithms, you have to include <cctype> header instead of
<ctype.h>. At least on my PC (Debian/gcc 3.3), <cctype> undefines all
tolower/etc macros and pulls ::tolower/::toupper/etc functions into
std namespace, so that your sample will work fine."
However, I'm quite sure the reason the call to transform fails is
because automatic type deduction fails. Is the comment made incorrect?
Also, are macro implementations allowed to be used in the C++
implementation?
Can you pass a macro in as a template parameter? eg
transform(i.begin(),i.end(),i.begin(), MY_MACRO) - maybe this would
create an anonymous function?
If MY_MACRO is an object-like macro, that line would pass whatever
MY_MACRO expands to. In the case of toupper from ctype.h, if toupper is
a macro, it's a function-like macro, so it needs an argument. When
there are no arguments the macro isn't used, and the name "toupper"
refers to the underlying function.
The actual problem with using toupper, which isn't solved by using
<cctype>, is that toupper expects non-negative values (unless the value
is EOF), but the standard doesn't require that char be unsigned, so
some valid character values can be negative.
--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)