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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 ...
In C and C++ arrays do not support the size function, so programmers often have to declare separate variable to hold the size, and pass it to procedures as a separate parameter. Elements of a newly created array may have undefined values (as in C), or may be defined to have a specific "default" value such as 0 or a null pointer (as in Java).
Each pointer has a type it points to, but one can freely cast between pointer types (but not between a function pointer and an object pointer). A special pointer type called the “void pointer” allows pointing to any (non-function) object, but is limited by the fact that it cannot be dereferenced directly (it shall be cast).
In computer science, pointer analysis, or points-to analysis, is a static code analysis technique that establishes which pointers, or heap references, can point to which variables, or storage locations.
Java explicitly distinguishes between interfaces and classes. In C++, multiple inheritance and pure virtual functions make it possible to define classes that function almost like Java interfaces do, with a few small differences. Java has both language and standard library support for multi-threading.
The reset() method causes the position pointer to move to the mark pointer's position. Upon invocation of the clear() method or the flip() method the mark pointer is discarded. The clear() method does not ensure zero-ing of the buffer, but does return the limit pointer to the upper boundary of the underlying array, and the position pointer to zero.
Function rank is an important concept to array programming languages in general, by analogy to tensor rank in mathematics: functions that operate on data may be classified by the number of dimensions they act on. Ordinary multiplication, for example, is a scalar ranked function because it operates on zero-dimensional data (individual numbers).
While a pointer contains the address of the item to which it refers, a handle is an abstraction of a reference which is managed externally; its opacity allows the referent to be relocated in memory by the system without invalidating the handle, making it similar to virtual memory for pointers, but even more abstracted.