list(3C++)

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 management.

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 constructor. 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 management.

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 function 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 capacity, 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 erasing 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 contained 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 functions, when not restricted by compiler limitations, allow you to use any type of input iterator as arguments. For compilers that do not support this feature, substitute functions 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 function 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 substitute 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 arguments. 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.

Museum

list(3C++)

NAME

SYNOPSIS

DESCRIPTION

INTERFACE

CONSTRUCTORS

DESTRUCTORS

ASSIGNMENT OPERATORS

ALLOCATORS

ITERATORS

MEMBER FUNCTIONS

NON-MEMBER OPERATORS

SPECIALIZED ALGORITHMS

EXAMPLE

WARNINGS

SEE ALSO