<regex> operators

The latest version of this topic can be found at <regex> operators.

operator!=

Not equal 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);

template <class BidIt, class Alloc>  
bool operator!=(const match_results<BidIt, Alloc>& left,  
    const match_results<BidIt, Alloc>& right);

Parameters

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.

Remarks

Each template operator returns !(left == right).

Example

// std_tr1__regex__operator_ne.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 << "match == " << mr.str() << std::endl;   
    std::cout << "sub == " << sub << std::endl;   
    std::cout << std::endl;   
  
    std::cout << "match != match == " << std::boolalpha   
        << (mr != mr) << 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);   
    }  
  

match == caaa  
sub == aaa  
  
match != match == false  
sub != sub == false  
string("aab") != sub == true  
sub != string("aab") == true  
"aab" != sub == true  
sub != "aab" == true  
'a' != sub == true  
sub != 'a' == true  

operator<

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);

Parameters

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.

Remarks

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.

Example

// 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  

operator<<

Inserts a sub_match in a stream.

template <class Elem, class IOtraits, class Alloc, class BidIt>  
basic_ostream<Elem, IOtraits>& operator<<(basic_ostream<Elem, IOtraits>& os,  
    const sub_match<BidIt>& right);

Parameters

Elem
The element type.

IOtraits
The string traits class.

Alloc
The allocator class.

BidIt
The iterator type.

os
The output stream.

right
The object to insert.

Remarks

The template operator returns os << right.str().

Example

// std_tr1__regex__operator_ins.cpp   
// compile with: /EHsc   
#include <regex>   
#include <iostream>   
  
int main()   
    {   
    std::regex rx("c(a*)|(b)");   
    std::cmatch mr;   
  
    std::regex_search("xcaaay", mr, rx);   
  
    std::csub_match sub = mr[0];   
    std::cout << "whole match: " << sub << std::endl;   
  
    return (0);   
    }  
  

whole match: caaa  

operator<=

Less than or equal 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);

Parameters

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.

Remarks

Each template operator returns !(right < left).

Example

// std_tr1__regex__operator_le.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 == true  
string("aab") <= sub == false  
sub <= string("aab") == true  
"aab" <= sub == false  
sub <= "aab" == true  
'a' <= sub == true  
sub <= 'a' == false  

operator==

Equal 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);

template <class BidIt, class Alloc>  
bool operator==(const match_results<BidIt, Alloc>& left,  
    const match_results<BidIt, Alloc>& right);

Parameters

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.

Remarks

Each template operator converts each of its arguments to a string type and returns the result of comparing the converted objects for equality.

When a template operator converts its arguments to a string type it uses the first of the following transformations that applies:

arguments whose types are a specialization of template class match_results or sub_match are converted by calling the str member function;

arguments whose types are a specialization of the template class basic_string are unchanged;

all other argument types are converted by passing the argument value to the constructor for an appropriate specialization of the template class basic_string.

Example

// std_tr1__regex__operator_eq.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 << "match == " << mr.str() << std::endl;   
    std::cout << "sub == " << sub << std::endl;   
    std::cout << std::endl;   
  
    std::cout << "match == match == " << std::boolalpha   
        << (mr == mr) << 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);   
    }  
  

match == caaa  
sub == aaa  
  
match == match == true  
sub == sub == true  
string("aab") == sub == false  
sub == string("aab") == false  
"aab" == sub == false  
sub == "aab" == false  
'a' == sub == false  
sub == 'a' == false  

operator>

Greater 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);

Parameters

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.

Remarks

Each template operator returns right < left.

Example

// std_tr1__regex__operator_gt.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 == true  
sub > string("aab") == false  
"aab" > sub == true  
sub > "aab" == false  
'a' > sub == false  
sub > 'a' == true  

operator>=

Greater than or equal 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);

Parameters

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.

Remarks

Each template operator returns !(left < right).

Example

// std_tr1__regex__operator_ge.cpp   
// compile with: /EHsc   
#include <regex>   
#include <iostream>   
  
typedef std::tr1std::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 == true  
string("aab") >= sub == true  
sub >= string("aab") == false  
"aab" >= sub == true  
sub >= "aab" == false  
'a' >= sub == false  
sub >= 'a' == true  

See Also

<regex>