public member function
<vector>

std::vector::shrink_to_fit

void shrink_to_fit();
Shrink to fit
Requests the container to reduce its capacity to fit its size.

The request is non-binding, and the container implementation is free to optimize otherwise and leave the vector with a capacity greater than its size.

This may cause a reallocation, but has no effect on the vector size and cannot alter its elements.

Parameters

none

Return value

none

Example

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// vector::shrink_to_fit
#include <iostream>
#include <vector>

int main ()
{
  std::vector<int> myvector (100);
  std::cout << "1. capacity of myvector: " << myvector.capacity() << '\n';

  myvector.resize(10);
  std::cout << "2. capacity of myvector: " << myvector.capacity() << '\n';

  myvector.shrink_to_fit();
  std::cout << "3. capacity of myvector: " << myvector.capacity() << '\n';

  return 0;
}


Possible output:
1. capacity of myvector: 100
2. capacity of myvector: 100
3. capacity of myvector: 10

Complexity

Up to linear in size.

Iterator validity

If a reallocation happens, all iterators, pointers and references related to the container are invalidated.
Otherwise, no changes.

Data races

The container is modified.
If a reallocation happens, all contained elements are modified.
Otherwise, no contained elements are accessed.

Exception safety

If the type of the elements is either copyable or no-throw moveable, there are no changes in the container in case of exception (strong guarantee).
Otherwise, if an exception is thrown, the container is left with a valid state (basic guarantee).

See also