std::vector::resize

 

C++

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void resize( size_type count, T value = T() );		(until C++11)
void resize( size_type count );	(1)	(since C++11)
void resize( size_type count, const value_type& value );	(2)	(since C++11)

Resizes the container to contain count elements.

If the current size is greater than count, the container is reduced to its first count elements as if by repeatedly calling pop_back().

If the current size is less than count, additional elements are appended and initialized with copies of value.	(until C++11)
If the current size is less than count, 1) additional value-initialized elements are appended 2) additional copies of value are appended	(since C++11)

Parameters

count	-	new size of the container
value	-	the value to initialize the new elements with
Type requirements
- T must meet the requirements of DefaultConstructible and MoveInsertable in order to use overload (1).
- T must meet the requirements of CopyInsertable in order to use overload (2).

Return value

(none)

Complexity

Linear in the size of the container

Notes

If value-initialization is undesirable, for example, if the elements are of non-class type and zeroing out is not needed, it can be avoided by providing a custom Allocator::constuct.

Vector capacity is never reduced when resizing to smaller size because that would invalidate all iterators, rather than only the ones that would be invalidated by the equivalent sequence of pop_back() calls.

See also

size	returns the number of elements (public member function)
insert	inserts elements (public member function)
erase	erases elements (public member function)