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std::basic_string<CharT,Traits,Allocator>::shrink_to_fit

From cppreference.com
< cpp‎ | string‎ | basic string
 
 
 
std::basic_string
 
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 if the request is fulfilled.

If (and only if) reallocation takes place, all pointers, references, and iterators are invalidated.

Contents

[edit] Parameters

(none)

[edit] Return value

(none)

[edit] Complexity

(unspecified) (until C++17)
Linear in the size of the string (since C++17)


[edit] Example

#include <iostream>
#include <string>
 
int main()
{
    std::string s;
    std::cout << "Default-constructed capacity is " << s.capacity() 
        << " and size is " << s.size() << '\n';
    for (int i=0; i<42; i++)
        s.append(" 42 ");
    std::cout << "Capacity after a couple of appends is " << s.capacity() 
        << " and size is " << s.size() << '\n';
    s.clear();
    std::cout << "Capacity after clear() is " << s.capacity() 
        << " and size is " << s.size() << '\n';
    s.shrink_to_fit();
    std::cout << "Capacity after shrink_to_fit() is " << s.capacity() 
        << " and size is " << s.size() << '\n';
}

Possible output:

Default-constructed capacity is 15 and size 0
Capacity after a couple of appends is 240 and size 168
Capacity after clear() is 240 and size 0
Capacity after shrink_to_fit() is 15 and size 0

[edit] See also

returns the number of characters
(public member function) [edit]
returns the number of characters that can be held in currently allocated storage
(public member function) [edit]