Using tolower in transform

T

TheDD

Hello,

i don't manage to use the tolower() function:

#include <algorithm>
#include <iostream>
#include <locale>
#include <string>

using std::cout;
using std::ctype;
using std::endl;
using std::locale;
using std::string;
using std::transform;
using std::use_facet;

typedef ctype< char > char_ctype_facet;

int
main()
{
locale loc("");
const char_ctype_facet& ct = use_facet< char_ctype_facet >(loc);
string str("Hello world.");

transform(str.begin(), str.end(),
str.begin(), ct.tolower);

cout << str << endl;
return 0;
}

$ g++ -W -Wall -std=c++98 -pedantic tolower.cc
tolower.cc: In function `int main()':
tolower.cc:24: error: no matching function for call to
`transform(__gnu_cxx::__normal_iterator<char*, std::basic_string<char,
std::char_traits<char>, std::allocator<char> > >,
__gnu_cxx::__normal_iterator<char*, std::basic_string<char,
std::char_traits<char>, std::allocator<char> > >,
__gnu_cxx::__normal_iterator<char*, std::basic_string<char,
std::char_traits<char>, std::allocator<char> > >, <unknown type>)'

ct.tolower is <unknow type>

What am i doing wrong?
 
V

Victor Bazarov

TheDD said:
Hello,

i don't manage to use the tolower() function:

#include <algorithm>
#include <iostream>
#include <locale>
#include <string>

using std::cout;
using std::ctype;
using std::endl;
using std::locale;
using std::string;
using std::transform;
using std::use_facet;

typedef ctype< char > char_ctype_facet;

int
main()
{
locale loc("");
const char_ctype_facet& ct = use_facet< char_ctype_facet >(loc);
string str("Hello world.");

transform(str.begin(), str.end(),
str.begin(), ct.tolower);
Click to expand...

Wouldn't

transform(str.begin(), str.end(), str.begin(), tolower);

do the trick?
cout << str << endl;
return 0;
}

$ g++ -W -Wall -std=c++98 -pedantic tolower.cc
tolower.cc: In function `int main()':
tolower.cc:24: error: no matching function for call to
`transform(__gnu_cxx::__normal_iterator<char*, std::basic_string<char,
std::char_traits<char>, std::allocator<char> > >,
__gnu_cxx::__normal_iterator<char*, std::basic_string<char,
std::char_traits<char>, std::allocator<char> > >,
__gnu_cxx::__normal_iterator<char*, std::basic_string<char,
std::char_traits<char>, std::allocator<char> > >, <unknown type>)'

ct.tolower is <unknow type>

What am i doing wrong?
Click to expand...

Not sure.

Victor
 
T

TheDD

Victor said:
[...]
locale loc("");
const char_ctype_facet& ct = use_facet< char_ctype_facet >(loc);
string str("Hello world.");

transform(str.begin(), str.end(),
str.begin(), ct.tolower);
Click to expand...

Wouldn't

transform(str.begin(), str.end(), str.begin(), tolower);

do the trick?
Click to expand...

yes it does, thx a lot.

But in this case, i guess the used locale is "C". What can i do to use
another one?
 
V

Victor Bazarov

TheDD said:
Victor Bazarov wrote:

[...]
locale loc("");
const char_ctype_facet& ct = use_facet< char_ctype_facet >(loc);
string str("Hello world.");

transform(str.begin(), str.end(),
str.begin(), ct.tolower);
Click to expand...

Wouldn't

transform(str.begin(), str.end(), str.begin(), tolower);

do the trick?
Click to expand...


yes it does, thx a lot.

But in this case, i guess the used locale is "C". What can i do to use
another one?
Click to expand...

Good question. Could you temporarily set it as "global one to use"
somehow? I am not that familiar with locales, as you probably figured
out by now...

V
 
T

TheDD

Victor said:
Good question. Could you temporarily set it as "global one to use"
somehow? I am not that familiar with locales, as you probably figured
out by now...
Click to expand...

Well i can use:

locale::global(locale(""));

but it's not really great. I'm going to read the docs one more time :)
 
V

Victor Bazarov

TheDD said:
i don't manage to use the tolower() function:

#include <algorithm>
#include <iostream>
#include <locale>
#include <string>

using std::cout;
using std::ctype;
using std::endl;
using std::locale;
using std::string;
using std::transform;
using std::use_facet;

typedef ctype< char > char_ctype_facet;

int
main()
{
locale loc("");
const char_ctype_facet& ct = use_facet< char_ctype_facet >(loc);
string str("Hello world.");

transform(str.begin(), str.end(),
str.begin(), ct.tolower);
Click to expand...

If you have to use a member function, try something like

std::transform(str.begin(), str.end(), str.begin(),
std::bind1st(std::mem_fun(&ctype<char>::tolower), ct));

I couldn't get it to compile, but dig in that direction.
cout << str << endl;
return 0;
}

$ g++ -W -Wall -std=c++98 -pedantic tolower.cc
tolower.cc: In function `int main()':
tolower.cc:24: error: no matching function for call to
`transform(__gnu_cxx::__normal_iterator<char*, std::basic_string<char,
std::char_traits<char>, std::allocator<char> > >,
__gnu_cxx::__normal_iterator<char*, std::basic_string<char,
std::char_traits<char>, std::allocator<char> > >,
__gnu_cxx::__normal_iterator<char*, std::basic_string<char,
std::char_traits<char>, std::allocator<char> > >, <unknown type>)'

ct.tolower is <unknow type>

What am i doing wrong?
Click to expand...

To use a member function, you need 'mem_fun'.

Victor
 
R

rossum

Hello,

i don't manage to use the tolower() function:

#include <algorithm>
#include <iostream>
#include <locale>
#include <string>
Click to expand...

#include said:
using std::cout;
using std::ctype;
using std::endl;
using std::locale;
using std::string;
using std::transform;
using std::use_facet;

typedef ctype< char > char_ctype_facet;

int
main()
{
locale loc("");
const char_ctype_facet& ct = use_facet< char_ctype_facet >(loc);
string str("Hello world.");

transform(str.begin(), str.end(),
str.begin(), ct.tolower);

cout << str << endl;
return 0;
}

$ g++ -W -Wall -std=c++98 -pedantic tolower.cc
tolower.cc: In function `int main()':
tolower.cc:24: error: no matching function for call to
`transform(__gnu_cxx::__normal_iterator<char*, std::basic_string<char,
std::char_traits<char>, std::allocator<char> > >,
__gnu_cxx::__normal_iterator<char*, std::basic_string<char,
std::char_traits<char>, std::allocator<char> > >,
__gnu_cxx::__normal_iterator<char*, std::basic_string<char,
std::char_traits<char>, std::allocator<char> > >, <unknown type>)'

ct.tolower is <unknow type>

What am i doing wrong?
Click to expand...

You need to include a library that includes tolower.

rossum
(Who has done the same sort of thing more often than he cares to
remember.)
 
T

TheDD

Le 28/05/2004 à 23:29:31 said:
You need to include a library that includes tolower.

rossum
(Who has done the same sort of thing more often than he cares to
remember.)
Click to expand...

same error message, doesn't seem to be that.
 
T

TheDD

Victor said:
If you have to use a member function, try something like

std::transform(str.begin(), str.end(), str.begin(),
std::bind1st(std::mem_fun(&ctype<char>::tolower), ct));

I couldn't get it to compile, but dig in that direction.
Click to expand...

Well i don't have a member function.

This works:

#include <algorithm>
#include <iostream>
#include <locale>
#include <string>
#include <functional>

using std::cout;
using std::endl;
using std::locale;
using std::string;
using std::transform;
using std::bind2nd;

struct s : std::binary_function< char, locale, char >
{
char operator ()(char c, const locale & loc) const
{
/* use:
* template<typename CharT>
* CharT std::tolower ( CharT c,
* const locale & __loc
* )
*/
return std::tolower(c, loc);
}
};

int
main()
{
locale loc("");
string str("Hello world.");

// use s operator ()
transform(str.begin(), str.end(),
str.begin(), bind2nd(s(), loc));

cout << str << endl;
return 0;
}


but is really not classy.
 
V

Victor Bazarov

TheDD said:
Well i don't have a member function.
Click to expand...

If you didn't, why were you trying to say

ct.tolower

? Isn't the notation '.' meant for member access? I must
be missing something here...

V
 
K

Klaus Eichner

TheDD said:
Hello,

i don't manage to use the tolower() function:

#include <algorithm>
#include <iostream>
#include <locale>
#include <string>

using std::cout;
using std::ctype;
using std::endl;
using std::locale;
using std::string;
using std::transform;
using std::use_facet;

typedef ctype< char > char_ctype_facet;

int
main()
{
locale loc("");
const char_ctype_facet& ct = use_facet< char_ctype_facet >(loc);
string str("Hello world.");

transform(str.begin(), str.end(),
str.begin(), ct.tolower);

cout << str << endl;
return 0;
}

$ g++ -W -Wall -std=c++98 -pedantic tolower.cc
tolower.cc: In function `int main()':
tolower.cc:24: error: no matching function for call to
`transform(__gnu_cxx::__normal_iterator<char*, std::basic_string<char,
std::char_traits<char>, std::allocator<char> > >,
__gnu_cxx::__normal_iterator<char*, std::basic_string<char,
std::char_traits<char>, std::allocator<char> > >,
__gnu_cxx::__normal_iterator<char*, std::basic_string<char,
std::char_traits<char>, std::allocator<char> > >, <unknown type>)'

ct.tolower is <unknow type>

What am i doing wrong?
Click to expand...

I am not sure, but it might be related to:
Bug#144409: g++-3.0: does not support transform(begin,end,begin,tolower)
idiom
http://lists.debian.org/debian-gcc/2002/04/msg00092.html
 

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