std::locale::operator()
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template< class CharT, class Traits, class Alloc >
bool operator()( const basic_string<CharT,Traits,Alloc>& s1, |
||
Compares two string arguments s1
and s2
according to the lexicographic comparison rules defined by this locale's std::collate<charT> facet. This operator allows any locale object that has a collate facet to be used as a binary predicate in the standard algorithms (such as std::sort) and ordered containers (such as std::set)
Contents |
[edit] Parameters
s1 | - | the first string to compare |
s2 | - | the second string to compare |
[edit] Return value
true if s1
is lexicographically less than s2
, false otherwise.
[edit] Possible implementation
template<class CharT, class Traits, class Alloc > bool operator()(const std::basic_string<CharT,Traits,Alloc>& s1, const std::basic_string<CharT,Traits,Alloc>& s2) const; { return std::use_facet<std::collate<CharT>>(*this).compare( s1.data(), s1.data() + s1.size(), s2.data(), s2.data() + s2.size() ) < 0; } |
[edit] Example
A vector of strings can be sorted according to a non-default locale by using the locale object as comparator:
Run this code
#include <locale> #include <algorithm> #include <vector> #include <string> #include <cassert> int main() { std::vector<std::wstring> v = {L"жил", L"был", L"кот"}; std::sort(v.begin(), v.end(), std::locale("ru_RU.UTF8")); assert(v[0] == L"был"); assert(v[1] == L"жил"); assert(v[2] == L"кот"); }
[edit] See also
defines lexicographical comparison and hashing of strings (class template) |