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In the C++ programming language, a reference is a simple reference datatype that is less powerful but safer than the pointer type inherited from C. The name C++ reference may cause confusion, as in computer science a reference is a general concept datatype, with pointers and C++ references being specific reference datatype implementations.
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 ...
The std::string type is the main string datatype in standard C++ since 1998, but it was not always part of C++. From C, C++ inherited the convention of using null-terminated strings that are handled by a pointer to their first element, and a library of functions that manipulate such strings.
Both the C99 and C++11 standards require at least one argument, but since C++20 this limitation has been lifted through the __VA_OPT__ functional macro. The __VA_OPT__ macro is replaced by its argument when arguments are present, and omitted otherwise. Common compilers also permit passing zero arguments before this addition, however. [4] [6]
This was recognized as a defect in the standard and fixed in C++.) [4] C++11 and C11 add two types with explicit widths char16_t and char32_t. [5] Variable-width encodings can be used in both byte strings and wide strings. String length and offsets are measured in bytes or wchar_t, not in "characters", which can be confusing to beginning ...
Perl supports hard references, which function similarly to those in other languages, and symbolic references, which are just string values that contain the names of variables. When a value that is not a hard reference is dereferenced, Perl considers it to be a symbolic reference and gives the variable with the name given by the value. [3]
A tracking reference in C++/CLI is a handle of a passed-by-reference variable. It is similar in concept to using *& (reference to a pointer) in standard C++, and (in function declarations) corresponds to the ref keyword applied to types in C#, or ByRef in Visual Basic .NET. C++/CLI uses a ^% syntax to indicate a tracking reference to a handle.
The specification for pass-by-reference or pass-by-value would be made in the function declaration and/or definition. Parameters appear in procedure definitions; arguments appear in procedure calls. In the function definition f(x) = x*x the variable x is a parameter; in the function call f(2) the value 2 is the argument of the function. Loosely ...