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operator< <regex>

Less than comparison for various objects.

template<class BidIt>
    bool operator<(const sub_match<BidIt>& left,
        const sub_match<BidIt>& right);
template<class BidIt, class IOtraits, class Alloc>
    bool operator<(
        const basic_string<typename iterator_traits<BidIt>::value_type, IOtraits, Alloc>& left,
        const sub_match<BidIt>& right);
template<class BidIt, class IOtraits, class Alloc>
    bool operator<(const sub_match<BidIt>& left,
        const basic_string<typename iterator_traits<BidIt>::value_type, IOtraits, Alloc>& right);
template<class BidIt>
    bool operator<(const typename iterator_traits<BidIt>::value_type *left,
        const sub_match<BidIt>& right);
template<class BidIt>
    bool operator<(const sub_match<BidIt>& left,
        const typename iterator_traits<BidIt>::value_type *right);
template<class BidIt>
    bool operator<(const typename iterator_traits<BidIt>::value_type& left,
        const sub_match<BidIt>& right);
template<class BidIt>
    bool operator<(const sub_match<BidIt>& left,
        const typename iterator_traits<BidIt>::value_type& right);
BidIt

The iterator type.

IOtraits

The string traits class.

Alloc

The allocator class.

left

The left object to compare.

right

The right object to compare.

Each template operator converts its arguments to a string type and returns true only if the converted value of left compares less than the converted value of right.

 

// std_tr1__regex__operator_lt.cpp 
// compile with: /EHsc 
#include <regex> 
#include <iostream> 
 
typedef std::cmatch::string_type Mystr; 
int main() 
    { 
    std::regex rx("c(a*)|(b)"); 
    std::cmatch mr; 
 
    std::regex_search("xcaaay", mr, rx); 
 
    std::csub_match sub = mr[1]; 
    std::cout << "sub == " << sub << std::endl; 
    std::cout << std::endl; 
 
    std::cout << "sub < sub == " << std::boolalpha 
        << (sub < sub) << std::endl; 
 
    std::cout << "string(\"aab\") < sub == " << std::boolalpha 
        << (Mystr("aab") < sub) << std::endl; 
    std::cout << "sub < string(\"aab\") == " << std::boolalpha 
        << (sub < Mystr("aab")) << std::endl; 
 
    std::cout << "\"aab\" < sub == " << std::boolalpha 
        << ("aab" < sub) << std::endl; 
    std::cout << "sub < \"aab\" == " << std::boolalpha 
        << (sub < "aab") << std::endl; 
 
    std::cout << "'a' < sub == " << std::boolalpha 
        << ('a' < sub) << std::endl; 
    std::cout << "sub < 'a' == " << std::boolalpha 
        << (sub < 'a') << std::endl; 
 
    return (0); 
    } 
 
sub == aaa

sub < sub == false
string("aab") < sub == false
sub < string("aab") == true
"aab" < sub == false
sub < "aab" == true
'a' < sub == true
sub < 'a' == false

Header: <regex>

Namespace: std

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