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# std::vector::resize

From cppreference.com
< cpp‎ | container‎ | vector

[edit template]

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)

### [edit] 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).

### [edit] Return value

(none)

### [edit] 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.

### [edit] See also

size | returns the number of elements (public member function) [edit]
insert | inserts elements (public member function) [edit]
erase | erases elements (public member function) [edit]

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