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regex_iterator Class

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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