std::list::resize

 

C++

Language

Standard Library Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Filesystem library (C++17)

Technical Specifications

 

Containers library

array (C++11)

vector

deque

forward_list (C++11)

list

set

multiset

map

multimap

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

stack

queue

priority_queue

span (C++20)

 

std::list

Member functions

list::list

list::~list

list::operator=

list::assign

list::get_allocator

Element access

list::front

list::back

Iterators

list::beginlist::cbegin (C++11)

list::endlist::cend (C++11)

list::rbeginlist::crbegin (C++11)

list::rendlist::crend (C++11)

Capacity

list::empty

list::size

list::max_size

Modifiers

list::clear

list::insert

list::emplace (C++11)

list::erase

list::push_front

list::emplace_front (C++11)

list::pop_front

list::push_back

list::emplace_back (C++11)

list::pop_back

list::resize

list::swap

Operations

list::merge

list::splice

list::removelist::remove_if

list::reverse

list::unique

list::sort

Deduction guides(C++17)

 

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.

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 default-inserted 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 DefaultInsertable 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 difference between the current size and count.

Example

Run this code

#include <iostream>
#include <list>
int main()
{
    std::list<int> c = {1, 2, 3};
    std::cout << "The list holds: ";
    for(auto& el: c) std::cout << el << ' ';
    std::cout << '\n';
    c.resize(5);
    std::cout << "After resize up to 5: ";
    for(auto& el: c) std::cout << el << ' ';
    std::cout << '\n';
    c.resize(2);
    std::cout << "After resize down to 2: ";
    for(auto& el: c) std::cout << el << ' ';
    std::cout << '\n';
}

Output:

The list holds: 1 2 3
After resize up to 5: 1 2 3 0 0
After resize down to 2: 1 2

See also

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