比如非 const 成员使用[],这会触发 COW,因为无法知晓应用程序是否会对返回的字符做修改。典型的如Legality of COW std::string implementation in C++11中举的例子: std::strings("str");constchar* p = s.data(); {std::strings2(s); (void) s[0];// 触发COW} std::cout << *p <<'\n';// ...
典型的如Legality of COW std::string implementation in C++11中举的例子：
Initializes a new instance of the String class to the Unicode characters indicated in the specified character array. String(Char*, Int32, Int32) Initializes a new instance of the String class to the value indicated by a specified pointer to an array of Unicode characters, a starting charact...
and the number of holes in the string. The handler can use this information to do a variety of things, such as guessing at how much space will be needed for the whole formatting operation and renting an initial buffer fromArrayPool<char...
一下内容来自http://www.kogonuso.com/2015/03/why-string-is-immutable-or-final-class.html#sthash.VgLU1mDY.dpuf. 发现百度的中文版本基本也是此文的翻译版。 缓存的需要 String是不可变的。因为String会被String pool缓存。因为缓存String字面量要在多个线程之间共享,一个客户端的行为会影响其他所有的客户端,...
An implementation may choose to perform conversion and concatenation in one step to avoid creating and then discarding an intermediateStringobject. To increase the performance of repeated string concatenation, a Java compiler may use theStringBufferclass or a similar technique to reduce the number of ...
( size_type count, value_type char_value, const allocator_type& alloc_type); template <class InputIterator> basic_string( InputIterator first, InputIterator last); template <class InputIterator> basic_string( InputIterator first, InputIterator last, const allocator_type& alloc_type); basic_...
For example, for better performance it is recommended that you override getCharacters(_:range:) and give it a faster implementation. You might want to implement an initializer for your subclass that is suited to the backing store that the subclass is managing. The NSString class does not have...
usingSystem;publicclassExample{publicstaticvoidMain(){// Show hash code in current domain.DisplayString display =newDisplayString(); display.ShowStringHashCode();// Create a new app domain and show string hash code.AppDomain domain = AppDomain.CreateDomain("NewDomain");vardisplay2 = (DisplayString...
using System; public class Example { public static void Main() { // Show hash code in current domain. DisplayString display = new DisplayString(); display.ShowStringHashCode(); // Create a new app domain and show string hash code. AppDomain domain = AppDomain.CreateDomain("NewDomain"); va...