Portable way to compare strings using case-insensitive

[Diego Martins]

Hi! The following code snippet:

namespace {
bool charCompare(cha r a, char b) {
return tolower(a) < tolower(b);
}
}

bool compareString(c onst std::string & s1, const std::string & s2)
{
return
std::lexicograp hical_compare(s 1.begin(),s1.en d(),s2.begin(), s2.end(),charCo mpare);
}

presents a compareString function to compare strings ignoring the case

compareString(" yes","YES") --true;

but

compareString(" ahá","AHÁ") --false;

how can I make it more portable to using accents, for example?

what are your background in this issue? what about using a Locale
class? (actually, I know nothing about locales in C++)

a possible idea is using classes to deal with character encode.
something like that:

compareString<I SO8859_1>("ahá" ,"AHÁ")

and it will delegate to charCompare<T>

an alternative is to use an overload like that:
bool compareString(c onst std::string & s1, const std::string & s2,
const CharConv & conv)

and CharConv can be a conversion table or a class that implements
tolower() and toupper() for each desired character codification

can you comment the ideas above?

any better ideas?

Diego Martins
HP