OOP: Function (Definitions)

"(1) A defined objective or characteristic action of a system or component. For example, a system may have inventory control as its primary function. (2) A software module that performs a specific action, is invoked by the appearance of its name in an expression, may receive input values, and returns a single value." (IEEE," IEEE Standard Glossary of Software Engineering Terminology", 1990) 

"A set of instructions that operates as a single logical unit, can be called by name, accepts input parameters, and returns information. In programming languages such as C, a function is a named subroutine of a program that encapsulates some logic. The function can be called by name, using parameters to pass data into the function and retrieve data produced by the function." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A block of code that performs a service, such as adding two numbers or printing to the screen." (Jesse Liberty, "Sams Teach Yourself C++ in 24 Hours" 3rd Ed., 2001)

"A program that returns a value to the program or environment from which it is called." (Bill Pribyl & Steven Feuerstein, "Learning Oracle PL/SQL", 2001)

"A routine that processes data inside a program." (Greg Perry, "Sams Teach Yourself Beginning Programming in 24 Hours" 2nd Ed., 2001)

"A block of statements identified by a name that can accept one or more arguments passed to it by value and can optionally return a value. Functions can be local (static) to the file in which they're defined or global, in which case they can be called from functions or methods defined in other files." (Stephen G Kochan, "Programming in Objective-C", 2003)

"A named set of predefined programming language commands that performs a specific task given zero, one, or more arguments and returns a value." (Bob Bryla, "Oracle Database Foundations", 2004)

"A piece of code that operates as a single logical unit. A function is called by name, accepts optional input parameters, and returns a status and optional output parameters. Many programming languages support functions, including C, Visual Basic, and Transact-SQL. Transact-SQL supplies built-in functions, which cannot be modified, and supports user-defined functions, which can be created and modified by users." (Jim Joseph, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"A block of statements identified by a name that can accept one or more arguments passed to it by value and can optionally return a value. Functions can be either local (static) to the file in which they’re defined or global, in which case they can be called from functions or methods defined in other files." (Stephen G Kochan, "Programming in Objective-C" 4th Ed., 2011)

"A packaged set of code that other pieces of code can invoke and that returns a result value." (Rod Stephens, "Stephens' Visual Basic Programming 24-Hour Trainer", 2011)

"A single block of code that accomplishes a single task and can be reused." (Matt Telles, "Beginning Programming", 2014)