regex_iterator Class
Iterator class for matches.
Syntax
template<class BidIt,
class Elem = typename std::iterator_traits<BidIt>::value_type,
class RxTraits = regex_traits<Elem> >
class regex_iterator
Parameters
BidIt
The iterator type for submatches.
Elem
The type of elements to match.
RXtraits
Traits class for elements.
Remarks
The class template 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).
Constructors
| Constructor | Description |
|---|---|
| regex_iterator | Constructs the iterator. |
Typedefs
| Type name | Description |
|---|---|
| difference_type | The type of an iterator difference. |
| iterator_category | The type of the iterator category. |
| pointer | The type of a pointer to a match. |
| reference | The type of a reference to a match. |
| regex_type | The type of the regular expression to match. |
| value_type | The type of a match. |
Operators
| Operator | Description |
|---|---|
| operator!= | Compares iterators for inequality. |
| operator* | Accesses the designated match. |
| operator++ | Increments the iterator. |
| operator= | Compares iterators for equality. |
| operator-> | Accesses the designated match. |
Requirements
Header: <regex>
Namespace: std
Examples
See the following articles for examples on regular expressions:
// std__regex__regex_iterator.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::difference_type
The type of an iterator difference.
typedef std::ptrdiff_t difference_type;
Remarks
The type is a synonym for std::ptrdiff_t.
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.
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).
regex_iterator::operator*
Accesses the designated match.
const match_results<BidIt>& operator*();
Remarks
The member function returns the stored value match.
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.
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.
regex_iterator::operator->
Accesses the designated match.
const match_results<BidIt> * operator->();
Remarks
The member function returns the address of the stored value match.
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.
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.
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.
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>.
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.
See also
<regex>
regex_constants Class
regex_error Class
<regex> functions
regex_iterator Class
<regex> operators
regex_token_iterator Class
regex_traits Class
<regex> typedefs