Define Functions in computer programming?

Question

What are the classes of functions?

Answer 1

Computer programming (often simply programming or coding) is the craft of implementing interrelated abstract algorithms and concepts using a particular programming language to produce a concrete computer program. Programming has elements of science, mathematics, and engineering. In software engineering, programming (implementation) is regarded as one phase in a software development process.


The only programming language a computer can directly execute is machine language (sometimes called "machine code"). Originally all programmers worked out every detail of the machine code, but this is hardly ever done anymore. Instead, programmers write source code, and a computer (running a compiler, an interpreter or occasionally an assembler) translates it through one or more translation steps to fill in all the details, before the final machine code is executed on the target computer. Even when complete low-level control of the target computer is required, programmers write assembly language, whose instructions are mnemonic one-to-one transcriptions of the corresponding machine language instructions.

Different programming languages support different styles of programming (called programming paradigms). Part of the art of programming is selecting one of the programming languages best suited for the task at hand. Different programming languages require different levels of detail to be handled by the programmer when implementing algorithms, often resulting in a compromise between ease of use and performance (a trade-off between "programmer time" and "computer time").

In some languages, an interpretable p-code binary (or byte-code) is generated, rather than machine language. Bytecode is used in the popular Java programming language by Sun Microsystems as well as Microsoft's recent .NET family of languages (MS.NET's P-Code is called the Intermediate Language or IL) and Visual Basic previous to the .NET version.

A brief history of programming
The earliest programmable machine (that is, a machine that can adjust its capabilities based upon changing its "program") can be said to be the Jacquard Loom, which was developed in 1801. The machine used a series of pasteboard cards with holes punched in them. The hole pattern represented the pattern that the loom had to follow in weaving cloth. The loom could produce entirely different weaves using different sets of cards. This innovation was later refined by Herman Hollerith of IBM in the development of the famous IBM punch card.

Another early use of computer programs were made using a soldering iron and a large number of vacuum tubes (later transistors). As programs became more complex, this became almost impossible, as one mistake would likely render the whole program useless. As data storage media became more advanced, it became possible to re-use one program for many things according to the content of the memory. A person would spend quite some time making punch cards that would hold a list of instructions for a computer. Every model of computer would be likely to need different instructions to do the same task. As computers became more powerful, and storage media became re-usable, it became possible to use the computer to make the program. Programmers quickly began to favor text over 1s and 0s, and punch cards were phased out. Over time and especially thanks to the manufacture and the development of Integrated Circuits computers have become extremely powerful, and this has resulted in a branch of programming called scripting. Programming has become gradually easier as new languages are invented but this has opened the scene to script kiddies, who are generally seen as an annoyance because of their lack of skill whilst often claiming to be hackers.


Examples of Programming Languages
C is a compiled procedural programming language made popular as the basis of Unix.
[[C++]] is an object oriented compiled programming language and one of the most widely-used programming languages currently available. It is often considered to be the industry-standard language of game development, but is also very often used to write other types of computer software applications. C++ was developed by Bjarne Stroustrup and was based on the programming language C. C++ retains the syntax and many familiar functions of C, but also adds various object-oriented programming concepts such as classes.
Python is complex and flexible yet easy to use language. It can be used to create program objects, that is, programs that can be recycled. Python can be integrated with other languages and it can be run on virtually any platform. The language Python is even available for some cell phones.
Java is an object oriented interpreted programming language. It has gained popularity in the past few years for its ability to be run on many platforms, including Microsoft Windows, Linux, Mac OS, and other systems. It was developed by Sun Microsystems.
JavaScript is a scripted language and is the basic client end language of the web.
Lisp is a functional, sometimes scripted, programming language often used in AI.
Pascal is a general-purpose structured language named after the famous mathematician and philosopher Blaise Pascal. It was very popular during the 80's and 90's.
PHP is a widely-used general-purpose open source scripting language that is especially suited for Web development and can be embedded into HTML.
Visual Basic a very basic programming concepts language used specifically for the creation of standard applications as opposed to video games and other programs requiring complex animation procedures, designed and developed by Microsoft.

Answer 2

a function is a block of reusable code that generally (but not always) returns a single value

typical examples are mathematical funtions (such as log or tan), string functions (such as finding occurrences of one string within another) and date functions (such as the number of days between 2 dates)

in languages like SQL (databases) functions can also return tables

Answer 3

Multi-user vs. Single-user A multi-user operating system allows multiple users to access a computer system concurrently. Time-sharing system can be classified as multi-user systems as they enable a multiple user access to a computer through the sharing of time. Single-user operating systems, as opposed to a multi-user operating system, are usable by a single user at a time. Being able to have multiple accounts on a Windows operating system does not make it a multi-user system. Rather, only the network administrator is the real user. But for a Unix-like operating system, it is possible for two users to login at a time and this capability of the OS makes it a multi-user operating system.

Answer 4

functions are block of codes that are written to perform a specific task.they have return types and parameters.
they get arguments from the calling module and
they perform the operation and return the result as specified in their definition and return types to the calling module.