regex_iterator Class
The latest version of this topic can be found at regex_iterator Class.
Iterator class for matches.
Syntax
class regex_iterator {
public:
typedef basic_regex<Elem, RXtraits>
regex_type;
typedef match_results<BidIt> value_type;
typedef std::forward_iterator_tag iterator_category;
typedef std::ptrdiff_t difference_type;
typedef const match_results<BidIt>* pointer;
typedef const match_results<BidIt>& reference;
regex_iterator();
regex_iterator(BidIt first, BidIt last,
const regex_type& re,
regex_constants::match_flag_type f = regex_constants::match_default);
bool operator==(const regex_iterator& right);
bool operator!=(const regex_iterator& right);
const match_results<BidIt>& operator*();
const match_results<BidIt> * operator->();
regex_iterator& operator++();
regex_iterator& operator++(int);
BidIt begin;
// exposition only
BidIt end;
// exposition only
regex_type *pregex; // exposition only
regex_constants::match_flag_type flags; // exposition only
match_results<BidIt> match;
// exposition only
};
Parameters
BidIt
The iterator type for submatches.
Elem
The type of elements to match.
RXtraits
Traits class for elements.
Remarks
The template class describes a constant forward iterator object. It extracts objects of type match_results<BidIt> by repeatedly applying its regular expression object *pregex to the character sequence defined by the iterator range [begin, end).
Examples
See the following topics for examples on regular expressions:
Requirements
Header: <regex>
Namespace: std
regex_iterator::difference_type
The type of an iterator difference.
typedef std::ptrdiff_t difference_type;
Remarks
The type is a synonym for std::ptrdiff_t.
Example
// std_tr1__regex__regex_iterator_difference_type.cpp
// compile with: /EHsc
#include <regex>
#include <iostream>
typedef std::regex_iterator<const char *> Myiter;
int main()
{
const char *pat = "axayaz";
Myiter::regex_type rx("a");
Myiter next(pat, pat + strlen(pat), rx);
Myiter end;
for (; next != end; ++next)
std::cout << "match == " << next->str() << std::endl;
// other members
Myiter it1(pat, pat + strlen(pat), rx);
Myiter it2(it1);
next = it1;
Myiter::iterator_category cat = std::forward_iterator_tag();
Myiter::difference_type dif = -3;
Myiter::value_type mr = *it1;
Myiter::reference ref = mr;
Myiter::pointer ptr = &ref;
dif = dif; // to quiet "unused" warnings
ptr = ptr;
return (0);
}
match == a
match == a
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regex_iterator::iterator_category
The type of the iterator category.
typedef std::forward_iterator_tag iterator_category;
Remarks
The type is a synonym for std::forward_iterator_tag.
Example
// std_tr1__regex__regex_iterator_iterator_category.cpp
// compile with: /EHsc
#include <regex>
#include <iostream>
typedef std::regex_iterator<const char *> Myiter;
int main()
{
const char *pat = "axayaz";
Myiter::regex_type rx("a");
Myiter next(pat, pat + strlen(pat), rx);
Myiter end;
for (; next != end; ++next)
std::cout << "match == " << next->str() << std::endl;
// other members
Myiter it1(pat, pat + strlen(pat), rx);
Myiter it2(it1);
next = it1;
Myiter::iterator_category cat = std::forward_iterator_tag();
Myiter::difference_type dif = -3;
Myiter::value_type mr = *it1;
Myiter::reference ref = mr;
Myiter::pointer ptr = &ref;
dif = dif; // to quiet "unused" warnings
ptr = ptr;
return (0);
}
match == a
match == a
match == a
regex_iterator::operator!=
Compares iterators for inequality.
bool operator!=(const regex_iterator& right);
Parameters
right
The iterator to compare to.
Remarks
The member function returns !(*this == right).
Example
// std_tr1__regex__regex_iterator_operator_ne.cpp
// compile with: /EHsc
#include <regex>
#include <iostream>
typedef std::regex_iterator<const char *> Myiter;
int main()
{
const char *pat = "axayaz";
Myiter::regex_type rx("a");
Myiter next(pat, pat + strlen(pat), rx);
Myiter end;
for (; next != end; ++next)
std::cout << "match == " << next->str() << std::endl;
// other members
Myiter it1(pat, pat + strlen(pat), rx);
Myiter it2(it1);
next = it1;
Myiter::iterator_category cat = std::forward_iterator_tag();
Myiter::difference_type dif = -3;
Myiter::value_type mr = *it1;
Myiter::reference ref = mr;
Myiter::pointer ptr = &ref;
dif = dif; // to quiet "unused" warnings
ptr = ptr;
return (0);
}
match == a
match == a
match == a
regex_iterator::operator*
Accesses the designated match.
const match_results<BidIt>& operator*();
Remarks
The member function returns the stored value match.
Example
// std_tr1__regex__regex_iterator_operator_star.cpp
// compile with: /EHsc
#include <regex>
#include <iostream>
typedef std::regex_iterator<const char *> Myiter;
int main()
{
const char *pat = "axayaz";
Myiter::regex_type rx("a");
Myiter next(pat, pat + strlen(pat), rx);
Myiter end;
for (; next != end; ++next)
std::cout << "match == " << next->str() << std::endl;
// other members
Myiter it1(pat, pat + strlen(pat), rx);
Myiter it2(it1);
next = it1;
Myiter::iterator_category cat = std::forward_iterator_tag();
Myiter::difference_type dif = -3;
Myiter::value_type mr = *it1;
Myiter::reference ref = mr;
Myiter::pointer ptr = &ref;
dif = dif; // to quiet "unused" warnings
ptr = ptr;
return (0);
}
match == a
match == a
match == a
regex_iterator::operator++
Increments the iterator.
regex_iterator& operator++();
regex_iterator& operator++(int);
Remarks
If the current match has no characters the first operator calls regex_search(begin, end, match, *pregex, flags | regex_constants::match_prev_avail | regex_constants::match_not_null); otherwise it advances the stored value begin to point to the first character after the current match then calls regex_search(begin, end, match, *pregex, flags | regex_constants::match_prev_avail). In either case, if the search fails the operator sets the object to an end-of-sequence iterator. The operator returns the object.
The second operator makes a copy of the object, increments the object, then returns the copy.
Example
// std_tr1__regex__regex_iterator_operator_inc.cpp
// compile with: /EHsc
#include <regex>
#include <iostream>
typedef std::regex_iterator<const char *> Myiter;
int main()
{
const char *pat = "axayaz";
Myiter::regex_type rx("a");
Myiter next(pat, pat + strlen(pat), rx);
Myiter end;
for (; next != end; ++next)
std::cout << "match == " << next->str() << std::endl;
// other members
Myiter it1(pat, pat + strlen(pat), rx);
Myiter it2(it1);
next = it1;
Myiter::iterator_category cat = std::forward_iterator_tag();
Myiter::difference_type dif = -3;
Myiter::value_type mr = *it1;
Myiter::reference ref = mr;
Myiter::pointer ptr = &ref;
dif = dif; // to quiet "unused" warnings
ptr = ptr;
return (0);
}
match == a
match == a
match == a
regex_iterator::operator=
Compares iterators for equality.
bool operator==(const regex_iterator& right);
Parameters
right
The iterator to compare to.
Remarks
The member function returns true if *this and right are both end-of-sequence iterators or if neither is an end-of-sequence iterator and begin == right.begin, end == right.end, pregex == right.pregex, and flags == right.flags. Otherwise it returns false.
Example
// std_tr1__regex__regex_iterator_operator_as.cpp
// compile with: /EHsc
#include <regex>
#include <iostream>
typedef std::regex_iterator<const char *> Myiter;
int main()
{
const char *pat = "axayaz";
Myiter::regex_type rx("a");
Myiter next(pat, pat + strlen(pat), rx);
Myiter end;
for (; next != end; ++next)
std::cout << "match == " << next->str() << std::endl;
// other members
Myiter it1(pat, pat + strlen(pat), rx);
Myiter it2(it1);
next = it1;
Myiter::iterator_category cat = std::forward_iterator_tag();
Myiter::difference_type dif = -3;
Myiter::value_type mr = *it1;
Myiter::reference ref = mr;
Myiter::pointer ptr = &ref;
dif = dif; // to quiet "unused" warnings
ptr = ptr;
return (0);
}
match == a
match == a
match == a
regex_iterator::operator->
Accesses the designated match.
const match_results<BidIt> * operator->();
Remarks
The member function returns the address of the stored value match.
Example
// std_tr1__regex__regex_iterator_operator_arrow.cpp
// compile with: /EHsc
#include <regex>
#include <iostream>
typedef std::regex_iterator<const char *> Myiter;
int main()
{
const char *pat = "axayaz";
Myiter::regex_type rx("a");
Myiter next(pat, pat + strlen(pat), rx);
Myiter end;
for (; next != end; ++next)
std::cout << "match == " << next->str() << std::endl;
// other members
Myiter it1(pat, pat + strlen(pat), rx);
Myiter it2(it1);
next = it1;
Myiter::iterator_category cat = std::forward_iterator_tag();
Myiter::difference_type dif = -3;
Myiter::value_type mr = *it1;
Myiter::reference ref = mr;
Myiter::pointer ptr = &ref;
dif = dif; // to quiet "unused" warnings
ptr = ptr;
return (0);
}
match == a
match == a
match == a
regex_iterator::pointer
The type of a pointer to a match.
typedef match_results<BidIt> *pointer;
Remarks
The type is a synonym for match_results<BidIt>*, where BidIt is the template parameter.
Example
// std_tr1__regex__regex_iterator_pointer.cpp
// compile with: /EHsc
#include <regex>
#include <iostream>
typedef std::regex_iterator<const char *> Myiter;
int main()
{
const char *pat = "axayaz";
Myiter::regex_type rx("a");
Myiter next(pat, pat + strlen(pat), rx);
Myiter end;
for (; next != end; ++next)
std::cout << "match == " << next->str() << std::endl;
// other members
Myiter it1(pat, pat + strlen(pat), rx);
Myiter it2(it1);
next = it1;
Myiter::iterator_category cat = std::forward_iterator_tag();
Myiter::difference_type dif = -3;
Myiter::value_type mr = *it1;
Myiter::reference ref = mr;
Myiter::pointer ptr = &ref;
dif = dif; // to quiet "unused" warnings
ptr = ptr;
return (0);
}
match == a
match == a
match == a
regex_iterator::reference
The type of a reference to a match.
typedef match_results<BidIt>& reference;
Remarks
The type is a synonym for match_results<BidIt>&, where BidIt is the template parameter.
Example
// std_tr1__regex__regex_iterator_reference.cpp
// compile with: /EHsc
#include <regex>
#include <iostream>
typedef std::regex_iterator<const char *> Myiter;
int main()
{
const char *pat = "axayaz";
Myiter::regex_type rx("a");
Myiter next(pat, pat + strlen(pat), rx);
Myiter end;
for (; next != end; ++next)
std::cout << "match == " << next->str() << std::endl;
// other members
Myiter it1(pat, pat + strlen(pat), rx);
Myiter it2(it1);
next = it1;
Myiter::iterator_category cat = std::forward_iterator_tag();
Myiter::difference_type dif = -3;
Myiter::value_type mr = *it1;
Myiter::reference ref = mr;
Myiter::pointer ptr = &ref;
dif = dif; // to quiet "unused" warnings
ptr = ptr;
return (0);
}
match == a
match == a
match == a
regex_iterator::regex_iterator
Constructs the iterator.
regex_iterator();
regex_iterator(BidIt first,
BidIt last,
const regex_type& re,
regex_constants::match_flag_type f = regex_constants::match_default);
Parameters
first
Beginning of sequence to match.
last
End of sequence to match.
re
Regular expression for matches.
f
Flags for matches.
Remarks
The first constructor constructs an end-of-sequence iterator. The second constructor initializes the stored value begin with first, the stored value end with last, the stored value pregex with &re, and the stored value flags with f. It then calls regex_search(begin, end, match, *pregex, flags). If the search fails, the constructor sets the object to an end-of-sequence iterator.
Example
// std_tr1__regex__regex_iterator_construct.cpp
// compile with: /EHsc
#include <regex>
#include <iostream>
typedef std::regex_iterator<const char *> Myiter;
int main()
{
const char *pat = "axayaz";
Myiter::regex_type rx("a");
Myiter next(pat, pat + strlen(pat), rx);
Myiter end;
for (; next != end; ++next)
std::cout << "match == " << next->str() << std::endl;
// other members
Myiter it1(pat, pat + strlen(pat), rx);
Myiter it2(it1);
next = it1;
Myiter::iterator_category cat = std::forward_iterator_tag();
Myiter::difference_type dif = -3;
Myiter::value_type mr = *it1;
Myiter::reference ref = mr;
Myiter::pointer ptr = &ref;
dif = dif; // to quiet "unused" warnings
ptr = ptr;
return (0);
}
match == a
match == a
match == a
regex_iterator::regex_type
The type of the regular expression to match.
typedef basic_regex<Elem, RXtraits> regex_type;
Remarks
The typedef is a synonym for basic_regex<Elem, RXtraits>.
Example
// std_tr1__regex__regex_iterator_regex_type.cpp
// compile with: /EHsc
#include <regex>
#include <iostream>
typedef std::regex_iterator<const char *> Myiter;
int main()
{
const char *pat = "axayaz";
Myiter::regex_type rx("a");
Myiter next(pat, pat + strlen(pat), rx);
Myiter end;
for (; next != end; ++next)
std::cout << "match == " << next->str() << std::endl;
// other members
Myiter it1(pat, pat + strlen(pat), rx);
Myiter it2(it1);
next = it1;
Myiter::iterator_category cat = std::forward_iterator_tag();
Myiter::difference_type dif = -3;
Myiter::value_type mr = *it1;
Myiter::reference ref = mr;
Myiter::pointer ptr = &ref;
dif = dif; // to quiet "unused" warnings
ptr = ptr;
return (0);
}
match == a
match == a
match == a
regex_iterator::value_type
The type of a match.
typedef match_results<BidIt> value_type;
Remarks
The type is a synonym for match_results<BidIt>, where BidIt is the template parameter.
Example
// std_tr1__regex__regex_iterator_value_type.cpp
// compile with: /EHsc
#include <regex>
#include <iostream>
typedef std::regex_iterator<const char *> Myiter;
int main()
{
const char *pat = "axayaz";
Myiter::regex_type rx("a");
Myiter next(pat, pat + strlen(pat), rx);
Myiter end;
for (; next != end; ++next)
std::cout << "match == " << next->str() << std::endl;
// other members
Myiter it1(pat, pat + strlen(pat), rx);
Myiter it2(it1);
next = it1;
Myiter::iterator_category cat = std::forward_iterator_tag();
Myiter::difference_type dif = -3;
Myiter::value_type mr = *it1;
Myiter::reference ref = mr;
Myiter::pointer ptr = &ref;
dif = dif; // to quiet "unused" warnings
ptr = ptr;
return (0);
}
match == a
match == a
match == a