std::string class, is there any built in lowercase converter?

#include <cctype>#include <string>std::string str = "Hello World!";for(int i=0; i<str.size();++i)   str = tolower(str);

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Original post by Fruny It's not the ideal way, but that will do the work. I'm sure somebody will come along shortly to post the transform + locale + functor version [grin]

std::transform(theString.begin(), theString.end(), theString.begin(), tolower);

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Original post by johnnyBravo hmm on the net, it says tolower() arg is an ascii integer, and returns the lower ascii integer. does the class have some kind of ascii to string converter?

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Original post by load_bitmap_file Quote: Original post by Fruny It's not the ideal way, but that will do the work. I'm sure somebody will come along shortly to post the transform + locale + functor version [grin] Well, here's a halfway-there version: std::transform(theString.begin(), theString.end(), theString.begin(), tolower); Pretty much the same thing as Fruny's except you don't have to manually write the for loop yourself. Doesn't use any locale/functor goodness. EDIT: Now I'll join Fruny in waiting for someone to post the transform + locale + functor version [grin]

#include<functional>#include<string>std::transform(theString.begin(), theString.end(), theString.begin(), std::bind2nd(&std::tolower, locale("fr_FR")) );std::transform(theString.begin(), theString.end(), theString.begin(), std::bind2nd(&std::tolower, locale("POSIX")) );

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Original post by load_bitmap_file EDIT: Now I'll join Fruny in waiting for someone to post the transform + locale + functor version [grin]

#include <boost/bind.hpp> // bind#include <locale>         // tolower#include <algorithm>      // transform#include <string>template < typename ForwardIterator >inline ForwardIteratortolower(ForwardIterator first, ForwardIterator last,		const std::locale& locale_ref = std::locale()) {   using namespace boost;   using namespace std;   typedef typename std::iterator_traits<ForwardIterator>::value_type       value_type;   return transform(first, last, first, 		bind(&std::tolower<value_type>, _1, cref(locale_ref)));}template < typename CharT, typename Traits, typename Alloc >inline std::basic_string<CharT, Traits, Alloc>&tolower(std::basic_string<CharT, Traits, Alloc>& s,		const std::locale& locale_ref = std::locale()) {	   tolower(s.begin(), s.end(), locale_ref);   return s;}

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Original post by MrEvil Erm... #include<functional>#include<string>std::transform(theString.begin(), theString.end(), theString.begin(), std::bind2nd(&std::tolower, locale("fr_FR")) );std::transform(theString.begin(), theString.end(), theString.begin(), std::bind2nd(&std::tolower, locale("POSIX")) ); ?

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Original post by ReKlipz actually, you could do this: string start = "this iS a StRING"; char tmp[] = start.c_str(); strlwr(tmp); start = string(tmp); or something to that effect...

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Original post by Anon Mike The "call tolower on each character" algorithms discussed here don't work for anything except western european languages and not even all of those.

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Original post by snk_kid Quote: Original post by Anon Mike The "call tolower on each character" algorithms discussed here don't work for anything except western european languages and not even all of those. Either missed my post or i wasted my money on this book [grin]. Notice that there is template function of std::tolower in the C++ header locale that is a internationalized/localized version and independent of character type. I'm pretty sure that it probably just uses the facet std::ctype's tolower member function internally.

// In-place conversionstemplate <typename Elem, typename Traits, typename Ax>std::basic_string<Elem, Traits, Ax> &tolower(std::basic_string<Elem, Traits, Ax> *str){	std::use_facet<std::ctype<Elem> >(locale()).tolower(&*str->begin(), &*str->end());	return *str;}// Copy conversionstemplate <typename Elem, typename Traits, typename Ax>std::basic_string<Elem, Traits, Ax> tolower(std::basic_string<Elem, Traits, Ax> str){	std::use_facet<std::ctype<Elem> >(locale()).tolower(&*str.begin(), &*str.end());	return str;}

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Original post by snk_kid Quote: Original post by Anon Mike The "call tolower on each character" algorithms discussed here don't work for anything except western european languages and not even all of those. Either missed my post or i wasted my money on this book [grin]. Notice that there is template function of std::tolower in the C++ header locale that is a internationalized/localized version and independent of character type. I'm pretty sure that it probably just uses the facet std::ctype's tolower member function internally.

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Original post by mfawcett I think you're right, but to be sure you could just wrap that yourself.

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Original post by Anon Mike The fundamental problem is that there is not necessarily a one-to-one mapping between upper and lower case (all this assumes of course that there is even such a thing as case in a particular locale but that's a different issue). The canonical example is some German lower-case letter that maps to "SS" in upper-case. Apparently there are even some languages where the mapping is context-sensitive but I'm not enough of an expert to know for sure. The end result of all this is that to be correct you need to do a whole-string analysis which of course a character-by-character conversion doesn't do. Your code seems to resolve to call to std::transform which does things character-by-character. But like I said, I'm being pedantic. If the target is just English then character-by-character will work fine.

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Original post by snk_kid I've got conformation that std::tolower/touppwer is indeed just a convenience function that delegates to std::ctype::tolower/upper. On side note that code has a slight issue using the range version of std::ctype::toupper/lower, as std::basic_string isn't guaranteed to hold its elements contiguously in memory (although alot of imps still do) so the safest thing to do is to use something like std::transform with std::ctype::touppwer/lower single character version.