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Хостинг:
Standard C++ Library
Copyright 1998, Rogue Wave Software, Inc.
NAME
list
- A sequence that supports bidirectional iterators.
SYNOPSIS
#include <list>
template <class T, class Allocator = allocator<T> >
class list;
DESCRIPTION
list<T,Allocator> is a type of sequence that supports
bidirectional iterators. A list<T,Allocator> allows constant
time insert and erase operations anywhere within the
sequence, with storage management handled automatically.
Constant time random access is not supported.
Any type used for the template parameter T must include the
following (where T is the type, t is a value of T and u is a
const value of T):
Copy constructors T(t) and T(u)
Destructor t.~T()
Address of &t and &u yielding T* and const T* respectively
Assignment t = a where a is a (possibly const) value of T
INTERFACE
template <class T, class Allocator = allocator<T> >
class list {
public:
// typedefs
class iterator;
class const_iterator;
typedef typename
Allocator::reference reference;
typedef typename
Allocator::const_reference const_reference;
typedef typename
Allocator::size_type size_type;
typedef typename
Allocator::difference_type difference_type;
typedef T value_type;
typedef Allocator allocator_type;
typedef typename std::reverse_iterator<iterator>
reverse_iterator;
typedef typename std::reverse_iterator<const_iterator>
const_reverse_iterator;
// Construct/Copy/Destroy
explicit list (const Allocator& = Allocator());
explicit list (size_type);
list (size_type, const T&, const Allocator& =
Allocator())
template <class InputIterator>
list (InputIterator, InputIterator,
const Allocator& = Allocator());
list(const list<T, Allocator>& x);
~list();
list<T,Allocator>& operator= (const list<T,Allocator>&);
template <class InputIterator>
void assign (InputIterator, InputIterator);
void assign (size_type n, const T&);
allocator_type get allocator () const;
// Iterators
iterator begin ();
const_iterator begin () const;
iterator end ();
const_iterator end () const;
reverse_iterator rbegin ();
const_reverse_iterator rbegin () const;
reverse_iterator rend ();
const_reverse_iterator rend () const;
// Capacity
bool empty () const;
size_type size () const;
size_type max_size () const;
void resize (size_type);
void resize (size_type, T);
// Element Access
reference front ();
const_reference front () const;
reference back ();
const_reference back () const;
// Modifiers
void push_front (const T&);
void pop_front ();
void push_back (const T&);
void pop_back ();
iterator insert (iterator, const T&);
void insert (iterator, size_type, const T&);
template <class InputIterator>
void insert (iterator, InputIterator, InputIterator);
iterator erase (iterator);
iterator erase (iterator, iterator);
void swap (list<T, Allocator>&);
void clear ();
// Special mutative operations on list
void splice (iterator, list<T, Allocator>&);
void splice (iterator, list<T, Allocator>&, iterator);
void splice (iterator, list<T, Allocator>&, iterator,
iterator);
void remove (const T&);
template <class Predicate>
void remove_if (Predicate);
void unique ();
template <class BinaryPredicate>
void unique (BinaryPredicate);
void merge (list<T, Allocator>&);
template <class Compare>
void merge (list<T, Allocator>&, Compare);
void sort ();
template <class Compare>
void sort (Compare);
void reverse();
};
// Non-member List Operators
template <class T, class Allocator>
bool operator== (const list<T, Allocator>&,
const list<T, Allocator>&);
template <class T, class Allocator>
bool operator!= (const list<T, Allocator>&,
const list<T, Allocator>&);
template <class T, class Allocator>
bool operator< (const list<T, Allocator>&,
const list<T, Allocator>&);
template <class T, class Allocator>
bool operator> (const list<T, Allocator>&,
const list<T, Allocator>&);
template <class T, class Allocator>
bool operator<= (const list<T, Allocator>&,
const list<T, Allocator>&);
template <class T, class Allocator>
bool operator>= (const list<T, Allocator>&,
const list<T, Allocator>&);
// Specialized Algorithms
template <class T, class Allocator>
void swap (list<T,Allocator>&, list<T, Allocator>&);
CONSTRUCTORS
explicit list(const Allocator& alloc = Allocator());
Creates a list of zero elements. The list uses the
allocator alloc for all storage manage-
ment.
explicit list(size_type n);
Creates a list of length n, containing n copies of the
default value for type T. T must have a default construc-
tor. The list uses the allocator Allocator() for all
storage management.
list(size_type n, const T& value,
const Allocator& alloc = Allocator());
Creates a list of length n, containing n copies of value.
The list uses the allocator alloc for all storage manage-
ment.
template <class InputIterator>
list(InputIterator first, InputIterator last,
const Allocator& alloc = Allocator());
Creates a list of length last - first, filled with all
values obtained by dereferencing the InputIterators on
the range [first, last). The list uses the allocator
alloc for all storage management.
list(const list<T, Allocator>& x);
Creates a copy of x.
DESTRUCTORS
~list();
Releases any allocated memory for this list.
ASSIGNMENT OPERATORS
list<T, Allocator>&
operator=(const list<T, Allocator>& x)
Erases all elements in self, then inserts into self a
copy of each element in x. Returns a reference to *this.
ALLOCATORS
allocator_type
get_allocator() const;
Returns a copy of the allocator used by self for storage
management.
ITERATORS
iterator
begin();
Returns a bidirectional iterator that points to the first
element.
const_iterator
begin() const;
Returns a constant bidirectional iterator that points to
the first element.
iterator
end();
Returns a bidirectional iterator that points to the
past-the-end value.
const_iterator
end() const;
Returns a constant bidirectional iterator that points to
the past-the-end value.
reverse_iterator
rbegin();
Returns a bidirectional iterator that points to the
past-the-end value.
const_reverse_iterator
rbegin() const;
Returns a constant bidirectional iterator that points to
the past-the-end value.
reverse_iterator
rend();
Returns a bidirectional iterator that points to the first
element.
const_reverse_iterator
rend() const;
Returns a constant bidirectional iterator that points to
the first element.
MEMBER FUNCTIONS
template <class InputIterator>
void
assign(InputIterator first, InputIterator last);
Erases all elements contained in self, then inserts new
elements from the range [first, last).
void
assign(size_type n, const T& t);
Erases all elements contained in self, then inserts n
instances of the value of t.
reference
back();
Returns a reference to the last element.
const_reference
back() const;
Returns a constant reference to the last element.
void
clear();
Erases all elements from the list.
bool
empty() const;
Returns true if the size is zero.
iterator
erase(iterator position);
Removes the element pointed to by position. Returns an
iterator pointing to the element following the deleted
element, or end() if the deleted item was the last one in
this list.
iterator
erase(iterator first, iterator last);
Removes the elements in the range (first, last). Returns
an iterator pointing to the element following the element
following the last deleted element, or end() if there
were no elements after the deleted range.
reference
front();
Returns a reference to the first element.
const_reference
front() const;
Returns a constant reference to the first element.
iterator
insert(iterator position, const T& x);
Inserts x before position. Returns an iterator that
points to the inserted x.
void
insert(iterator position, size_type n, const T& x);
Inserts n copies of x before position.
template <class InputIterator>
void
insert(iterator position, InputIterator first,
InputIterator last);
Inserts copies of the elements in the range [first, last)
before position.
size_type
max_size() const;
Returns size() of the largest possible list.
void
merge(list<T, Allocator>& x);
Merges a sorted x with a sorted self using operator<. For
equal elements in the two lists, elements from self
always precede the elements from x. The merge function
leaves x empty.
template <class Compare>
void
merge(list<T, Allocator>& x, Compare comp);
Merges a sorted x with sorted self using a compare func-
tion object, comp. For identical elements in the two
lists, elements from self always precede the elements
from x. The merge function leaves x empty.
void
pop_back();
Removes the last element.
void
pop_front();
Removes the first element.
void
push_back(const T& x);
Appends a copy of x to the end of the list.
void
push_front(const T& x);
Appends a copy of x to the front of the list.
void
remove(const T& value);
template <class Predicate>
void
remove_if(Predicate pred);
Removes all elements in the list referenced by the list
iterator i for which *i == value or pred(*i) == true,
whichever is applicable. This is a stable operation. The
relative order of list items that are not removed is
preserved.
void
resize(size_type sz);
Alters the size of self. If the new size ( sz ) is
greater than the current size, sz-size() copies of the
default value of type T are inserted at the end of the
list. If the new size is smaller than the current capa-
city, then the list is truncated by erasing size()-sz
elements off the end. Otherwise, no action is taken. Type
T must have a default constructor.
void
resize(size_type sz, T c);
Alters the size of self. If the new size ( sz ) is
greater than the current size, sz-size() c's are inserted
at the end of the list. If the new size is smaller than
the current capacity, then the list is truncated by eras-
ing size()-sz elements off the end. Otherwise, no action
is taken.
void
reverse();
Reverses the order of the elements.
size_type
size() const;
Returns the number of elements.
void
sort();
Sorts self according to the operator<. sort maintains the
relative order of equal elements.
template <class Compare>
void
sort(Compare comp);
Sorts self according to a comparison function object,
comp. This is also a stable sort.
void
splice(iterator position, list<T, Allocator>& x);
Inserts x before position, leaving x empty.
void
splice(iterator position, list<T, Allocator>& x,
iterator i);
Moves the elements pointed to by iterator i in x to self,
inserting it before position. The element is removed from
x.
void
splice(iterator position, list<T, Allocator >& x,
iterator first, iterator last);
Moves the elements in the range [first, last) in x to
self, inserting them before position. The elements in the
range [first, last) are removed from x.
void
swap(list <T, Allocator>& x);
Exchanges self with x.
void
unique();
Erases copies of consecutive repeated elements leaving
the first occurrence.
template <class BinaryPredicate>
void
unique(BinaryPredicate binary_pred);
Erases consecutive elements matching a true condition of
the binary_pred. The first occurrence is not removed.
NON-MEMBER OPERATORS
template <class T, class Allocator>
bool operator==(const list<T, Allocator>& x,
const list<T, Allocator>& y);
Returns true if x is the same as y.
template <class T, class Allocator>
bool operator!=(const list<T, Allocator>& x,
const list<T, Allocator>& y);
Returns !(x==y).
template <class T, class Allocator>
bool operator<(const list<T, Allocator>& x,
const list<T,Allocator>& y);
Returns true if the sequence defined by the elements con-
tained in x is lexicographically less than the sequence
defined by the elements contained in y.
template <class T, class Allocator>
bool operator>(const list<T, Allocator>& x,
const list<T,Allocator>& y);
Returns y < x.
template <class T, class Allocator>
bool operator<=(const list<T, Allocator>& x,
const list<T,Allocator>& y);
Returns !(y < x).
template <class T, class Allocator>
bool operator>=(const list<T, Allocator>& x,
const list<T,Allocator>& y);
Returns !(x < y).
SPECIALIZED ALGORITHMS
template <class T, class Allocator>
void swap(list<T, Allocator>& a, list<T, Allocator>& b);
Swaps the contents of a and b.
EXAMPLE
//
// list.cpp
//
#include <list>
#include <string>
#include <iostream>
using namespace std;
// Print out a list of strings
ostream& operator<<(ostream& out, const list<string>& l)
{
copy(l.begin(), l.end(),
ostream_iterator<string,char>(cout," "));
return out;
}
int main(void)
{
// create a list of critters
list<string> critters;
int i;
// insert several critters
critters.insert(critters.begin(),"antelope");
critters.insert(critters.begin(),"bear");
critters.insert(critters.begin(),"cat");
// print out the list
cout << critters << endl;
// Change cat to cougar
*find(critters.begin(),critters.end(),"cat") = "cougar";
cout << critters << endl;
// put a zebra at the beginning
// an ocelot ahead of antelope
// and a rat at the end
critters.push_front("zebra");
critters.insert(find(critters.begin(),critters.end(),
"antelope"),"ocelot");
critters.push_back("rat");
cout << critters << endl;
// sort the list (Use list's sort function since the
// generic algorithm requires a random access iterator
// and list only provides bidirectional)
critters.sort();
cout << critters << endl;
// now let's erase half of the critters
int half = critters.size() >> 1;
for(i = 0; i < half; ++i) {
critters.erase(critters.begin());
}
cout << critters << endl;
return 0;
}
Program Output
cat bear antelope
cougar bear antelope
zebra cougar bear ocelot antelope rat
antelope bear cougar ocelot rat zebra
ocelot rat zebra
WARNINGS
Member function templates are used in all containers
included in the Standard Template Library. An example of
this feature is the constructor for list<T,_Allocator> that
takes two templatized iterators:
template <class InputIterator>
list (InputIterator, InputIterator,
const Allocator& = Allocator());
list also has an insert function of this type. These func-
tions, when not restricted by compiler limitations, allow
you to use any type of input iterator as arguments. For com-
pilers that do not support this feature, substitute func-
tions allow you to use an iterator obtained from the same
type of container as the one you are constructing (or
calling a member function on), or you can use a pointer to
the type of element you have in the container.
For example, if your compiler does not support member func-
tion templates, you can construct a list in the following
two ways:
int intarray[10];
list<int> first_list(intarray,intarray + 10);
list<int> second_list(first_list.begin(),first_list.end());
But not this way:
list<long> long_list(first_list.begin(),first_list.end());
since the long_list and first_list are not the same type.
Additionally, list includes a merge function of this type.
template <class Compare> void merge (list<T, Allocator>&,
Compare);
This function allows you to specify a compare function
object to be used in merging two lists. In this case, a sub-
stitute function is not included with the merge that uses
the operator< as the default. Thus, if your compiler does
not support member function templates, all list merges use
operator<.
Also, many compilers do not support default template argu-
ments. If your compiler is one of these, you always need to
supply the Allocator template argument. For instance, you
have to write:
list<int, allocator<int> >
instead of:
list<int>
If your compiler does not support namespaces, then you do
not need the using declaration for std.
SEE ALSO
allocator, Containers, Iterators
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