std::forward_list<T,Allocator>:: resize

Resizes the container to contain count elements, does nothing if count == std:: distance ( begin ( ) , end ( ) ) (i.e. if count is equal to the current size).

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 , then:

Parameters

Complexity

Linear in the difference between the current size and count . Additional complexity possible due to list traversal to reach the first element to erase/the end position to insert.

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 <forward_list>
#include <iostream>
 
void print(auto rem, const std::forward_list<int>& c)
{
    for (std::cout << rem; const int el : c)
        std::cout << el << ' ';
    std::cout << '\n';
}
 
int main()
{
    std::forward_list<int> c = {1, 2, 3};
    print("The forward_list holds: ", c);
 
    c.resize(5);
    print("After resize up to 5: ", c);
 
    c.resize(2);
    print("After resize down to 2: ", c);
 
    c.resize(6, 4);
    print("After resize up to 6 (initializer = 4): ", c);
}

The forward_list 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

See also