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In computer science, an associative array, map, symbol table, or dictionary is an abstract data type that stores a collection of (key, value) pairs, such that each possible key appears at most once in the collection. In mathematical terms, an associative array is a function with finite domain. [1] It supports 'lookup', 'remove', and 'insert ...
Although std::map is typically implemented using a self-balancing binary search tree, C++11 defines a second map called std::unordered_map, which has the algorithmic characteristics of a hash table. This is a common vendor extension to the Standard Template Library (STL) as well, usually called hash_map , available from such implementations as ...
The Python programming language includes extensive support for creating and manipulating symbol tables. [5] Properties that can be queried include whether a given symbol is a free variable or a bound variable, whether it is block scope or global scope, whether it is imported, and what namespace it belongs to.
If a symbol is unknown, the Lisp reader creates a new symbol. In Common Lisp, symbols have the following attributes: a name, a value, a function, a list of properties and a package. [6] In Common Lisp it is also possible that a symbol is not interned in a package. Such symbols can be printed, but when read back, a new symbol needs to be created.
Parse tree of Python code with inset tokenization. The syntax of textual programming languages is usually defined using a combination of regular expressions (for lexical structure) and Backus–Naur form (a metalanguage for grammatical structure) to inductively specify syntactic categories (nonterminal) and terminal symbols. [7]
The variadic template feature of C++ was designed by Douglas Gregor and Jaakko Järvi [1] [2] and was later standardized in C++11. Prior to C++11, templates (classes and functions) could only take a fixed number of arguments, which had to be specified when a template was first declared.
Modern programming languages use symbols to represent concepts and/or data and are, therefore, examples of symbolic languages. [1] Some programming languages (such as Lisp and Mathematica) make it easy to represent higher-level abstractions as expressions in the language, enabling symbolic programming. [2] [3]
In C++, associative containers are a group of class templates in the standard library of the C++ programming language that implement ordered associative arrays. [1] Being templates, they can be used to store arbitrary elements, such as integers or custom classes.