std::deque resize() method
- od C++11
- do C++11
// (1) Non const version only
void resize( size_type count );
// (2) Non const version only
void resize( size_type count, const value_type& value );
// (1) Non const version only
void resize( size_type count );
// (2) Non const version only
void resize( size_type count, T value = T() );
Resizes the container to contain count
elements.
If the current size is greater than count
, the container is reduced to its first count
elements.
If the current size is less than count
:
- (1) additional default-inserted elements are appended.
- (2) additional copies of
value
are appended.
Parameters
count
- new size of the containervalue
- the value to initialize the new elements with
Type requirements
T
is the in this list.
- (1) -
T
(container's element type) must meet the requirements ofMoveInsertable
andDefaultInsertable
- (2) -
T
(container's element type) must meet the requirements ofCopyInsertable
Return value
(none)
Complexity
Linear in the difference between the current size and count
- O(size() - count).
Exceptions
(none)
Notes
If value-initialization in overload (1) 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::construct()
.
Example
#include <iostream>
#include <deque>
int main()
{
std::deque<int> c = {1, 2, 3};
std::cout << "The deque holds: ";
for (const auto& el: c) std::cout << el << ' ';
std::cout << '\n';
c.resize(5);
std::cout << "After resize up to 5: ";
for (const auto& el: c) std::cout << el << ' ';
std::cout << '\n';
c.resize(2);
std::cout << "After resize down to 2: ";
for (const auto& el: c) std::cout << el << ' ';
std::cout << '\n';
c.resize(6, 4);
std::cout << "After resize up to 6 (initializer = 4): ";
for (const auto& el: c) std::cout << el << ' ';
std::cout << '\n';
}
The deque holds: 1 2 3
After resize up to 5: 1 2 3 0 0
After resize down to 2: 1 2
After resize up to 6 (initializer = 4): 1 2 4 4 4 4
Hover to see the original license.