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std::basic_...rink_to_fit(3)   C++ Standard Libary  std::basic_...rink_to_fit(3)

NAME
     std::basic_string::shrink_to_fit - std::basic_string::shrink_to_fit

Synopsis
	void shrink_to_fit();  (constexpr 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)

Notes
	In libstdc++, shrink_to_fit() is not available in C++98 mode.

Example
     // Run this code

      #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:
      GCC 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

      clang output (with -stdlib=libc++):
      Size of std::string is 24 bytes
      Default-constructed capacity is 22 and size is 0
      Capacity after 42 appends is 191 and size is 168
      Capacity after clear() is 191 and size is 0
      Capacity after shrink_to_fit() is 22 and size is 0

	Defect reports

	The following behavior-changing defect	reports  were  applied	retroac-
     tively to
	previously published C++ standards.

	  DR	Applied to		Behavior as published		    Cor-
     rect behavior
	LWG 755 C++98	   std::string lacked explicit shrink-to-fit	    pro-
     vided
			   operations

See also
	size	 returns the number of characters
	length	 (public member function)
		 returns  the number of characters that can be held in currently
     allocated
	capacity storage
		 (public member function)
	resize	 changes the number of characters stored
		 (public member function)

http://cppreference.com 	   2024.06.10	    std::basic_...rink_to_fit(3)
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