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Many languages have explicit pointers or references. Reference types differ from these in that the entities they refer to are always accessed via references; for example, whereas in C++ it's possible to have either a std:: string and a std:: string *, where the former is a mutable string and the latter is an explicit pointer to a mutable string (unless it's a null pointer), in Java it is only ...
Both Java and the .NET Framework have mutable versions of string. In Java [5]: 84 these are StringBuffer and StringBuilder (mutable versions of Java String) and in .NET this is StringBuilder (mutable version of .Net String). Python 3 has a mutable string (bytes) variant, named bytearray. [6]
In C#, a class is a reference type while a struct (concept derived from the struct in C language) is a value type. [5] Hence an instance derived from a class definition is an object while an instance derived from a struct definition is said to be a value object (to be precise a struct can be made immutable to represent a value object declaring attributes as readonly [6]).
In computer science, having value semantics (also value-type semantics or copy-by-value semantics) means for an object that only its value counts, not its identity. [1] [2] Immutable objects have value semantics trivially, [3] and in the presence of mutation, an object with value semantics can only be uniquely-referenced at any point in a program.
In C and C++, volatile is a type qualifier, like const, and is a part of a type (e.g. the type of a variable or field). The behavior of the volatile keyword in C and C++ is sometimes given in terms of suppressing optimizations of an optimizing compiler: 1- don't remove existing volatile reads and writes, 2- don't add new volatile reads and writes, and 3- don't reorder volatile reads and writes.
Some of these languages with immutable strings also provide another type that is mutable, such as Java and .NET's StringBuilder, the thread-safe Java StringBuffer, and the Cocoa NSMutableString. There are both advantages and disadvantages to immutability: although immutable strings may require inefficiently creating many copies, they are ...
This calling convention was common in the following 16-bit APIs: OS/2 1.x, Microsoft Windows 3.x, and Borland Delphi version 1.x. Modern versions of the Windows API use stdcall, which still has the callee restoring the stack as in the Pascal convention, but the parameters are now pushed right to left.
Boxing is the operation of converting a value of a value type into a value of a corresponding reference type. [15] Boxing in C# is implicit. Unboxing is the operation of converting a value of a reference type (previously boxed) into a value of a value type. [15] Unboxing in C# requires an explicit type cast. Example: