std::vector<T,Allocator>::shrink_to_fit (3) - Linux Manuals

std::vector<T,Allocator>::shrink_to_fit: std::vector<T,Allocator>::shrink_to_fit

NAME

std::vector<T,Allocator>::shrink_to_fit - std::vector<T,Allocator>::shrink_to_fit

Synopsis

void shrink_to_fit(); (since C++11)

Requests the removal of unused capacity.
It is a non-binding request to reduce capacity() to size(). It depends on the implementation whether the request is fulfilled.
If reallocation occurs, all iterators, including the past the end iterator, and all references to the elements are invalidated. If no reallocation takes place, no iterators or references are invalidated.

Parameters

(none)

Type requirements

Return value

(none)

Complexity

At most linear in the size of the container.

Notes

If an exception is thrown other than by T's move constructor, there are no effects.

Example

// Run this code

  #include <iostream>
  #include <vector>

  int main()
  {
      std::vector<int> v;
      std::cout << "Default-constructed capacity is " << v.capacity() << '\n';
      v.resize(100);
      std::cout << "Capacity of a 100-element vector is " << v.capacity() << '\n';
      v.clear();
      std::cout << "Capacity after clear() is " << v.capacity() << '\n';
      v.shrink_to_fit();
      std::cout << "Capacity after shrink_to_fit() is " << v.capacity() << '\n';
  }

Possible output:

  Default-constructed capacity is 0
  Capacity of a 100-element vector is 100
  Capacity after clear() is 100
  Capacity after shrink_to_fit() is 0