Collection (abstract data type) in the context of Object (computer science)

In computer science, a list or sequence is a collection of items that are finite in number and in a particular order. An instance of a list is a computer representation of the mathematical concept of a tuple or finite sequence.

A list may contain the same value more than once, and each occurrence is considered a distinct item.

In computer science, an associative array, key-value store, 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. It supports 'lookup', 'remove', and 'insert' operations.

The dictionary problem is the classic problem of designing efficient data structures that implement associative arrays.The two major solutions to the dictionary problem are hash tables and search trees.It is sometimes also possible to solve the problem using directly addressed arrays, binary search trees, or other more specialized structures.

In computer science, a pointer is an object in many programming languages that stores a memory address. This can be that of another value located in computer memory, or in some cases, that of memory-mapped computer hardware. A pointer references a location in memory, and obtaining the value stored at that location is known as dereferencing the pointer. As an analogy, a page number in a book's index could be considered a pointer to the corresponding page; dereferencing such a pointer would be done by flipping to the page with the given page number and reading the text found on that page. The actual format and content of a pointer variable is dependent on the underlying computer architecture.

Using pointers significantly improves performance for repetitive operations, like traversing iterable data structures (e.g. strings, lookup tables, control tables, linked lists, and tree structures). In particular, it is often much cheaper in time and space to copy and dereference pointers than it is to copy and access the data to which the pointers point.

In computer science, a stack is an abstract data type that serves as a collection of elements with two main operations:

• Push, which adds an element to the collection, and
• Pop, which removes the most recently added element.

Additionally, a peek operation can, without modifying the stack, return the value of the last element added (the item at the top of the stack). The name stack is an analogy to a set of physical items stacked one atop another, such as a stack of plates.