std::locale::operator()

Compares two string arguments s1 and s2 according to the lexicographic comparison rules defined by this locale’s std::collate 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).

# Declarations

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;

# Parameters

s1: the first string to compare
s2: the second string to compare

# Return value

true if s1 is lexicographically less than s2, false otherwise.

# Example

#include <algorithm>
#include <cassert>
#include <locale>
#include <string>
#include <vector>
 
int main()
{
    std::vector<std::wstring> v = {L"жил", L"был", L"пёс"};
    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"пёс");
}

# See also

collate