Overloading binary operator in c wikipedia
This may involve meta-programming specifying the operators in a separate language , or within the language itself. Definition of new operators, particularly runtime definition, often makes correct static analysis of programs impossible, since the syntax of the language may be Turing-complete, so even constructing the syntax tree may require solving the halting problem, which is impossible. This occurs for Perl , for example, and some dialects of Lisp. Common examples that differ syntactically are mathematical arithmetic operations, e.
Common examples that differ semantically by argument passing mode are boolean operations, which frequently feature short-circuit evaluation: A compiler can implement operators and functions with subroutine calls or with inline code. Some built-in operators supported by a language have a direct mapping to a small number of instructions commonly found on central processing units , though others e.
All operators have bold Alphanumeric equivalents, c. From Wikipedia, the free encyclopedia. This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources.
Unsourced material may be challenged and removed. January Learn how and when to remove this template message. The arity and precedence of the operator is then part of the phrase syntax of the language, which changes the phrase-level analysis.
For example, adding an operator requires lexing and tokenizing this character, and the phrase structure syntax tree depends on the arity and precedence of this operator.
Go , only one version is needed in the case of Go, post operators only. Such expressions generally invoke undefined behavior , and should be avoided. The following C code fragment illustrates the difference between the pre and post increment and decrement operators:. The post-increment operator is commonly used with array subscripts. Likewise, the post-decrement operator is commonly used with pointers:.
Apple's Swift once supported these operators,  but support was removed as of version 3. Pascal , Delphi , Modula-2 , and Oberon provide the same functions, but they are called inc x and dec x. The concept was introduced in the B programming language circa by Ken Thompson. They were not in the earliest versions of B, but appeared along the way.
People often guess that they were created to use the auto-increment and auto-decrement address modes provided by the DEC PDP on which C and Unix first became popular. This is historically impossible, since there was no PDP when B was developed. The PDP-7, however, did have a few 'auto-increment' memory cells, with the property that an indirect memory reference through them incremented the cell.
This feature probably suggested such operators to Thompson; the generalization to make them both prefix and postfix was his own. From Wikipedia, the free encyclopedia. This article needs additional citations for verification.
Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.