Kerala Plus Two Computer Science (DHSE) key terms

A variable that stores the memory address of another variable instead of a data value; dereferencing it with * accesses the stored object.

The unary * operator applied to a pointer, which gives access to the value stored at the address the pointer holds.

The unary & operator that returns the memory address where a variable is stored, commonly used to initialise a pointer.

A pointer that holds no valid address, usually written as nullptr in modern C++; dereferencing it is an error that can crash the program.

An alias for an existing variable, declared with & in C++; changes through the reference affect the original object directly.

A user-defined C++ data type grouping variables of possibly different types under one name, with members accessed using the dot operator.

A fault where dynamically allocated memory is never released with delete, so the program keeps consuming memory until it ends.

Reserving memory at run time with operators new and delete, so the size of storage can be decided while the program executes.

A collection of elements of the same type stored in consecutive memory locations and accessed by an index starting at zero.

A search that checks elements one by one from the start until the target is found or the list ends; works on unsorted data.

A search on a sorted array that repeatedly halves the search range by comparing the target with the middle element.

A linear structure following last-in-first-out order, where insertion (push) and deletion (pop) happen only at one end called the top.

A linear structure following first-in-first-out order, where elements are inserted at the rear and removed from the front.

A queue implemented so the rear wraps around to the beginning of the array, reusing freed slots and avoiding false overflow.

The error condition arising when an insertion is attempted into a stack or queue that already holds its maximum capacity.

The error condition arising when a deletion is attempted from an empty stack or queue, leaving nothing to remove.

A chain of nodes where each node stores data plus a pointer to the next node, allowing growth without contiguous memory.

The basic building block of a linked list, holding a data field and one or more link fields pointing to neighbouring nodes.

A blueprint in object-oriented programming that bundles data members and member functions; objects are instances created from it.

A concrete instance of a class that owns its own copy of the data members and can call the class member functions.

Wrapping data and the functions that operate on it inside one unit and restricting direct outside access, usually through private members.

Keeping class members private so that outside code cannot read or change them except through permitted public functions.

A keyword such as private, public or protected that decides which code may use a class member.

A special member function with the same name as its class, called automatically when an object is created, used to initialise members.

A member function named with a leading tilde that runs automatically when an object is destroyed, typically to free resources.

Declaring several constructors in one class with different parameter lists so objects can be created in different ways.

Deriving a new class from an existing one so the derived class reuses and extends the members of the base class.

The ability of the same function name or operator to behave differently depending on the object or arguments involved.

Defining multiple functions with the same name in one scope but different parameter lists, resolved by the compiler from the call.

A column or set of columns whose values uniquely identify each row of a table and which cannot be null.

A column in one table whose values must match a primary key value in another table, enforcing referential integrity between them.

The rule that a foreign key value must either be null or correspond to an existing primary key value in the referenced table.

Data Definition Language: SQL statements such as CREATE, ALTER and DROP that define or change the structure of database objects.

Data Manipulation Language: SQL statements such as SELECT, INSERT, UPDATE and DELETE that work on the data inside tables.

A SQL function such as SUM, AVG, COUNT, MIN or MAX that computes one summary value from a set of rows.

A SQL clause that arranges rows into groups sharing equal values in the listed columns, so aggregates are computed per group.

A markup instruction in HTML enclosed in angle brackets that tells the browser how to structure or present content.

A name-value pair written inside an HTML start tag that supplies extra information, such as href on a link or src on an image.

Cascading Style Sheets: rules that control the appearance of HTML elements, kept separate from content for easier maintenance.

The part of a CSS rule before the braces that states which elements the declaration block applies to, such as a tag, class or id.

Document Object Model: the tree of objects a browser builds from an HTML page, which scripts can read and modify.

A scripting language that runs in the browser to make web pages interactive, handling events and changing page content dynamically.

Code executed on the user's browser rather than the server, giving quick responses but visible to the user.

Code that runs on the web server to generate pages, process forms and access databases before sending output to the browser.

A server-side scripting language embedded in HTML using blocks, widely used with databases to build dynamic pages.

A way to keep data about one user across several page requests, stored on the server and identified by a session id.

A small piece of data a website stores in the user's browser and receives back on later requests to recognise the user.

HyperText Transfer Protocol: the request-response rules browsers and web servers use to exchange pages and other resources.

Uniform Resource Locator: the address identifying a resource on the web, giving its protocol, server name and path.

Domain Name System: a distributed service that translates human-readable domain names into the numeric IP addresses computers use.

A numeric label assigned to a device on a network so data can be routed to it; IPv4 uses four decimal octets.

An agreed set of rules governing how data is formatted, sent and acknowledged between devices on a network.

The core suite of internet protocols: IP handles addressing and routing of packets, while TCP provides reliable ordered delivery.

The arrangement of nodes and links in a network, such as star, bus, ring or mesh, which affects cost and fault tolerance.

Local Area Network: a network covering a small area such as a school or office, usually owned and managed by one organisation.

Discarded electronic equipment such as old computers and phones, which needs careful recycling because it contains toxic materials.

Designing and using computers in ways that reduce energy consumption and environmental harm, including recycling and virtualisation.

Delivering computing services such as storage and software over the internet on demand, instead of owning local hardware.

Using information technology to deliver government services and information to citizens more efficiently and transparently.