Callback, also known as a “call-back function,” is a subroutine in computer programming that is used to refer the control to a previous point in a running program. It is an asynchronous process that is used to inform a program of an event occurring in another part of a system. Callbacks are commonly used in operating systems to signal a non-deterministic event, such as an interrupt. Callbacks are used to pass away events from program to program in an object-oriented programming language as well as to transfer data from one program to another.
In C, callbacks are achieved by using pointers to functions. In other languages, the function name or a delegate object may be passed. The runtime environment of some languages, such as JavaScript, can handle callback functions without explicit coding of the function pointer or delegate.
A callback is an argument passed to a function. When the callback function is called, the arguments to the calling function are passed as arguments to the callback. This allows the same function to be used for different purposes depending on the context in which it is used. For example, a sorting algorithm like Quicksort can be used to sort an array of integers or a linked list of strings, depending on the callback passed.
Callbacks can also be used to implement callback chaining, which allows functions to be called in a chain-like fashion. In this way, it is possible for one function to call another function and the called function can call a third function and so on. This allows for an easy and efficient way to execute code in multiple locations.
Using callbacks can make code more readable by separating code into logical blocks and improving the development process of programs. Furthermore, since the callback functions are often written in a high-level language, they can also be used to help integrate various programming languages.
Callback programming is a very powerful feature in computer programming. It allows for asynchronous operation, which can result in faster program execution. Callbacks are used in all types of applications including web development, operating systems, languages, databases, and more.
