std::basic_string<CharT,Traits,Allocator>::shrink_to_fit
void shrink_to_fit(); |
(since C++11) (until C++20) |
|
constexpr void shrink_to_fit(); |
(since C++20) |
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.
Parameters
(none).
Return value
(none).
Complexity
(unspecified). |
(until C++17) |
Linear in the size of the string. |
(since C++17) |
Example
#include <iostream> #include <string> int main() { std::string s; std::cout << "Size of std::string is " << sizeof s << " bytes\n" << "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 42 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:
Size of std::string is 32 bytes Default-constructed capacity is 15 and size 0 Capacity after 42 appends is 240 and size 168 Capacity after clear() is 240 and size 0 Capacity after shrink_to_fit() is 15 and size 0
See also
returns the number of characters (public member function) |
|
returns the number of characters that can be held in currently allocated storage (public member function) |
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