Problem with <algorithm> transform

[Gerald I. Evenden]

Working on a Kubuntu 64bit system "c++ (GCC) 4.0.3".

The following simple program extracted from p.497 & 499 of N.M.Josurris'
"The C++ Standard Library ... " (file t.cpp):

1 #include <string>
2 #include <iostream>
3 #include <algorithm>
4 #include <cctype>
5 using namespace std;
6 int main() {
7 string s("This is the zip code of Hodna 1223");
8 cout << "original: " << s <<endl;
9 transform(s.beg in(), s.end(),s.begin (), toupper);
10 cout << "upper: " << s << endl;
11 }

results in the following error output when executing 'c++ t.cpp'

t.cpp: In function ‘int main()’:
t.cpp:9: error: no matching function for call
to ‘transform(__ gnu_cxx::__norm al_iterator<cha r*, std::basic_stri ng<char,
std::char_trait s<char>, std::allocator< char >,
__gnu_cxx::__no rmal_iterator<c har*, std::basic_stri ng<char,
std::char_trait s<char>, std::allocator< char >,
__gnu_cxx::__no rmal_iterator<c har*, std::basic_stri ng<char,
std::char_trait s<char>, std::allocator< char >, <unknown type>)’

Something seems seriously wrong but I can't figure it.

Help, suggestions greatly appreciated.

[James Kanze]

On Jan 7, 4:03 pm, "Gerald I. Evenden" <gerald.even... @verizon.mail>
wrote:

Digging through Prada's "C++ Primer Plus" (5th) I found notes
on p.936-7 relating to C library functions delared as having
int returns and problems thereof, so I added a line to t.cpp
and changed line 13's function name:

1 #include <string>
2 #include <iostream>
3 #include <algorithm>
4 #include <cctype>
5 using namespace std;
6 /* I added the following line because cctype
7 * apparently declares 'int toupper(char)'
8 */

It had better be: "int std::toupper( int )".

9 static char toUpper(char c) { return toupper(c); }

return toupper( static_cast< unsigned char >( c ) ) ;

It's undefined behavior to call the std::toupper( int ) above
with any negative value other than EOF, and char is often
signed.

10 int main() {
11 string s("This is the zip code of Hodna 1223");
12 cout << "original: " << s <<endl;
13 transform(s.beg in(), s.end(),s.begin (), toUpper);
14 cout << "upper: " << s << endl;
15 }

then:
gie@charon:~/Letters/src$ g++ t.cpp
gie@charon:~/Letters/src$ ./a.out
original: This is the zip code of Hodna 1223
upper: THIS IS THE ZIP CODE OF HODNA 1223
gie@charon:~/Letters/src$
Problem solved.

If all the code has to handle is this one string, then there are
much, much easier ways to do it. In general, the above code has
undefined behavior.

And of course, the reason why the code now compiles is because
there is only one isUpper function, so overload resolution has
no problem choosing.

--
James Kanze (GABI Software) mailto:ja****** ***@gmail.com
Conseils en informatique orient�e objet/
Beratung in objektorientier ter Datenverarbeitu ng
9 place S�mard, 78210 St.-Cyr-l'�cole, France, [phone]

[Gerald I. Evenden]

James Kanze wrote:

On Jan 7, 4:03 pm, "Gerald I. Evenden" <gerald.even... @verizon.mail>
wrote:

>Digging through Prada's "C++ Primer Plus" (5th) I found notes
on p.936-7 relating to C library functions delared as having
int returns and problems thereof, so I added a line to t.cpp
and changed line 13's function name:

1 #include <string>
2 #include <iostream>
3 #include <algorithm>
4 #include <cctype>
5 using namespace std;
6 /* I added the following line because cctype
7 * apparently declares 'int toupper(char)'
8 */

It had better be: "int std::toupper( int )".

Yes:

static int toUpper(int c) { return toupper(c); }

Works. This seems to negate Prada's argument about type problems.
Also
transform(s.beg in(), s.end(),s.begin (), ::toupper);
seems to work (also dropping the toUpper line):

Alas!! Too much Greek. Note "std::toupp er" does NOT work.

> 9 static char toUpper(char c) { return toupper(c); }

return toupper( static_cast< unsigned char >( c ) ) ;

It's undefined behavior to call the std::toupper( int ) above
with any negative value other than EOF, and char is often
signed.

> 10 int main() {
11 string s("This is the zip code of Hodna 1223");
12 cout << "original: " << s <<endl;
13 transform(s.beg in(), s.end(),s.begin (), toUpper);
14 cout << "upper: " << s << endl;
15 }

>then:
gie@charon:~/Letters/src$ g++ t.cpp
gie@charon:~/Letters/src$ ./a.out
original: This is the zip code of Hodna 1223
upper: THIS IS THE ZIP CODE OF HODNA 1223
gie@charon:~/Letters/src$
Problem solved.

If all the code has to handle is this one string, then there are
much, much easier ways to do it. In general, the above code has
undefined behavior.

Outside of resorting to C char types what would be the efficient
alternative? The above looks more nifty than what I would have
to do in straight C.

And of course, the reason why the code now compiles is because
there is only one isUpper function, so overload resolution has
no problem choosing.

First, I am a total C++ dumbkopf and only an old time C user that
likes to take advantages of some of C++ notational short cuts.
In this case I do not see where the overloading of toupper is coming
from. From what you say it seems to imply that there are multiple
declarations of toupper---where?? I have only seen toupper used
in this basic example and each referred to cctype which I assumed
contained the *only* definition.

Thanks for your comments. They sparked me to look a little further.

--
James Kanze (GABI Software) mailto:ja****** ***@gmail.com
Conseils en informatique orient�e objet/
Beratung in objektorientier ter Datenverarbeitu ng
9 place S�mard, 78210 St.-Cyr-l'�cole, France, [phone]