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The ti(vector) class implements an
hi(array: expandable)i(expandable array). Before using the tt(vector)
container the tthi(vector) header file must be included.
The following constructors, operators, and member functions are available:
itemization(
it() hi(vector constructors) Constructors:
itemization(
it() The copy and move constructors are available;
it() A tt(vector) may be constructed empty:
verb(vector<string> object;)
it() A vector may be initialized to a certain number of elements:
verb(vector<string> object(5, "Hello"s); // initialize to 5 Hello's,
vector<string> container(10); // and to 10 empty strings
vector<string> names = {"george", "frank", "tony", "karel"};)
Note the difference between tt(vector<int> first(5)) and tt(vector<int>
second{ 5 }). The vector tt(first) contains five elements, initialized to 0,
while the vector tt(second) contains one element, initialized to 5. Referring
back to section ref(PAIR): with the latter definition the compiler is able to
deduce
hi(class templates: deducing parameters) the vector's template parameter
type (tt(int)), so the latter definition could also have been written as
tt(vector second{ 5 }).
An ambiguity might be observed when looking at
verb(vector object{ vector{ 1 } };)
Did we define a tt(vector<int>) or a tt(vector<vector<int>>)? The standard
considers this a tt(vector<int>): it is initialized using the vector's move
constructor from an abstract tt(vector<int>).
)
it() A vector may be initialized using iterators. To
initialize a vector with elements 5 until 10 (including the last one) of an
existing tt(vector<string>) the following construction may be used:
verb(extern vector<string> container;
vector<string> object(&container[5], &container[11]);)
Note here that the last element pointed to by the second iterator
(tt(&container[11])) is em(not) stored in tt(object). This is a simple
example of the use of em(iterators), in which the used
i(range of values) starts at the first value, and includes all elements up
to but not including the element to which the second iterator refers. The
standard notation for this is rangeti(begin, end).
it() In addition to the standard operators for containers, the tt(vector)
supports the index operator, which can be used to retrieve or reassign
individual elements of the vector. Note that the elements which are indexed
must exist. For example, having defined an empty vector a statement like
tt(ivect[0] = 18) produces an error, as the vector is empty. So, the vector
is em(not) automatically
hi(automatic expansion) expanded, and tt(operator[]) does em(not) respect its
i(array bounds). In this case the vector should be resized first, or
tt(ivect.push_back(18)) should be used (see below). If you need run-time array
bound checking, use the vector's tt(at) member.
it() The tt(vector) class offers the following
hi(vector: member functions) member functions:
itemization(
ithtq(assign)(void assign(...))
(assigns new content to the vector:)
itemization(
itt(assign(iterator begin, iterator end)) assigns the values at
the iterator range rangett(begin, end) to the vector;
itt(assign(size_type n, value_type const &val)) assigns tt(n)
copies of tt(val) to the vector;
itt(assign(initializer_list<value_type> values)) assigns the
values in the initializer list to the vector.
)
ithtq(at)(Type &at(size_t idx))
(returns a reference to the vector's element at
index position tt(idx). If tt(idx) exceeds the vector's size a
tt(std::out_of_range) exception is thrown.)
ithtq(back)(Type &back())
(returns a reference to the last element in the
vector. It is the i(responsibility of the programmer) to use the member only
if the vector is not empty.)
ithtq(begin)(vector::iterator begin())
(returns an iterator pointing to the first
element in the vector, returning tt(end) if the vector is empty.)
ithtq(capacity)(size_t capacity())
(Number of elements for which memory has been
allocated. It returns at least the value returned by tt(size))
ithtq(cbegin)(vector::const_iterator cbegin())
(returns a const_iterator pointing to the first
element in the vector, returning tt(cend) if the vector is empty.)
ithtq(cend)(vector::const_iterator cend())
(returns a const_iterator pointing just beyond the
vector's last element.)
ithtq(clear)(void clear())
(erases all the vector's elements.)
ithtq(crbegin)(vector::const_reverse_iterator crbegin())
(returns a const_reverse_iterator pointing to the last
element in the vector, returning tt(crend) if the vector is empty.)
ithtq(crend)(vector::const_reverse_iterator crend())
(returns a const_reverse_iterator pointing just before the
vector's first element.)
ithtq(data)(value_type *data())
(returns a pointer to the vector's first data element.)
ithtq(emplace)
(iterator emplace(const_iterator position, Args &&...args))
(a tt(value_type) object is constructed from the arguments
specified after tt(position), and the newly created element is inserted at
tt(position). Different from tt(insert), which expects an existing object of
the container's value type (and inserts
the provided argument into the container) using copy or move construction or
assignment, tt(emplace) uses its arguments to
em(construct) such an object immediately at the intended location of the
container, without requiring copy or move construction or assignment.)
ithtq(emplace_back)(void emplace_back(Args &&...args))
(a tt(value_type) object is constructed from the member's
arguments, and the newly created element is inserted beyond the vector's last
element.)
ithtq(empty)(bool empty())
(returns tt(true) if the vector contains no
elements.)
ithtq(end)(vector::iterator end())
(returns an iterator pointing beyond the last
element in the vector.)
ithtq(erase)(vector::iterator erase())
(erases a specific range of elements in the vector:)
itemization(
itt(erase(pos)) erases the element pointed to by the iterator
tt(pos). The iterator tt(++pos) is returned.
itt(erase(first, beyond)) erases elements indicated by the iterator
range rangett(first, beyond), returning tt(beyond).
)
ithtq(front)(Type &front())
(returns a reference to the first element in the
vector. It is the responsibility of the programmer to use the member only if
the vector is not empty.)
ithtq(get_allocator)(allocator_type get_allocator() const)(returns a
copy of the allocator object used by the tt(vector) object.)
ithtq(insert)(... insert())
(elements may be inserted starting at a certain position. The
return value depends on the version of tt(insert()) that is called:)
itemization(
itt(vector::iterator insert(pos)) inserts a default value of type
tt(Type) at tt(pos), tt(pos) is returned.
itt(vector::iterator insert(pos, value)) inserts tt(value) at
tt(pos), tt(pos) is returned.
itt(void insert(pos, first, beyond)) inserts the elements in the
iterator range rangett(first, beyond).
itt(void insert(pos, n, value)) inserts tt(n) elements having value
tt(value) at position tt(pos).
)
ithtq(max_size)(size_t max_size())(returns the maximum number of
elements this tt(vector) may contain.)
ithtq(pop_back)(void pop_back())
(removes the last element from the vector. Avoid calling this
member on an empty vector: although nothing is returned its internally
maintained count of number of available elements is reduced, causing the
vector's tt(size()) member to return the (when cast to tt(int)) value -1, and
then -2, etc., etc.)
ithtq(push_back)(void push_back(value))
(adds tt(value) to the end of the vector.)
ithtq(rbegin)(vector::reverse_iterator rbegin())
(this member returns a reverse_iterator pointing to the last
element in the vector.)
ithtq(rend)(vector::reverse_iterator rend())
(returns an iterator pointing before the first element in the
vector.)
ithtq(reserve)(void reserve(size_t request))
(if tt(request) is less than or equal to tt(capacity), this
call has no effect. Otherwise, it is a request to allocate additional
memory. If the call is successful, then tt(capacity) returns a value of at
least tt(request). Otherwise, tt(capacity) is unchanged. In either case,
tt(size)'s return value won't change, until a function like tt(resize) is
called, actually changing the number of accessible elements.)
ithtq(resize)(void resize())
(can be used to alter the number of elements that
are currently stored in the vector:)
itemization(
itt(resize(n, value)) may be used to resize the vector to a size
of tt(n). tt(Value) is optional. If the vector is expanded and tt(value) is
not provided, the additional elements are initialized to the i(default value)
of the used data type, otherwise tt(value) is used to initialize extra
elements.
)
ithtq(shrink_to_fit)(void shrink_to_fit())(optionally reduces the
amount of memory allocated by a vector to its current size. The
implementor is free to ignore or otherwise optimize this request. In order to
guarantee a `shrink to fit' operation the
verb(vector<Type>(vectorObject).swap(vectorObject))
idiom can be used.)
ithtq(size)(size_t size())
(returns the number of elements in the vector.)
ithtq(swap)(void swap())
(swaps two vectors using identical data types. Example:)
verb(#include <iostream>
#include <vector>
using namespace std;
int main()
{
vector<int> v1(7);
vector<int> v2(10);
v1.swap(v2);
cout << v1.size() << " " << v2.size() << '\n';
}
/*
Produced output:
10 7
*/)
))
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