What exactly is the meaning of an API? [closed]

Answer 1

1. an API(Application Programming Interface) is a set of defined functions and methods for interfacing with the underlying operating system or another program or service running on the computer.

2. It is usually used by establishing a reference to a library in your software or importing a function from a dll.

3. It is used in one form or another in almost all software, being explicitly called in your program or implicitly called by the compiler.

Answer 2

An API defines the interfaces by which one piece of software communicates with another at the source level. It provides abstraction by providing a standard set of interfaces - usually functions - that one piece of software (typically a higher-level piece) can invoke from another piece of software (usually a lower-level piece).

For example, an API might abstract the concept of drawing text on the screen through a family of functions that provide everything needed to draw the text. The API merely defines the interface; the piece of software that actually provides the API is known as the implementation of the API.

It is common to call an API a "contract". This is not correct, at least in the legal sense of the term, as an API is not a two-way agreement. The API user (generally, the higher-level software) has zero input into the API and its implementation. It may use the API as-is, or not use it at all: take it or leave it!

A real-world example of an API is the interfaces defined by the C standard and implemented by the standard C library. This API defines a family of basic and essential functions, such as memory management and string manipulation routines.

Answer 3

1) What is an API?

API is a contract. A promise to perform described services when asked in specific ways.

2) How is it used?

According to the rules specified in the contract. The whole point of an API is to define how it's used.

3) When and where is it used?

It's used when 2 or more separate systems need to work together to achieve something they can't do alone.

Answer 4

It is a set of software components that interact with one another. It provides a set of functions, variables, and object classes for the creation of an application, operating system or any other thing.

Answer 5

An API is the interface through which you access someone elses code or through which someone else's code accesses yours. In effect the public methods and properties.

Answer 6

API stands for Application Programming Interface, i.e. API is the way for an application to interact with certain system/application/library/etc.

For example, there are API's for OS (WinAPI), API's for other applications (like databases) and for specific libraries (for example, image processing), etc.

APIs are usually developed in a form consumable by a client application. For C/C++ applications, it a set header files and dynamic/static libraries. For Java - set of jars. And so on.