Event-Driven Programming - Computer Science in Simple Words

By: Tasha Kolesnikova

8 min



Event-Driven Programming - Computer Science in Simple Words

The development of the ideas of structured and event-driven programming has significantly increased the productivity of programmers and made it possible to create applications of hundreds of thousands of lines in a reasonable time frame. Therefore, this technology is spoken about in all educational institutions associated with computer programming. If you are faced with this topic for the first time and understand the essence of the concept, we suggest reading our article - we will tell you about event-driven programming in simple words. We also offer coursework, term paper, dissertation help on all computer science topics.

Event-Driven Programming Definition

Event-driven programming is a programming paradigm in which program execution is determined by new user events (mouse clicks, keypresses), sensor outputs, or message passing from other programs. Programmers use Event-driven programming in graphical user interfaces and other applications that focus on performing user actions in response to user input (user clicks).

We can also define event-driven programming as a way of building a computer program, in which, in the essential function of the program, the main event loop of the application is explicitly highlighted in the code, the body of which consists of two parts: fetching the event and event handling. In an event-driven application, the main loop listens for events and triggers a callback function when one of those events is detected.

Event Handlers

An event handler is a function that handles or responds to a specific event. Event-driven programming uses this feature in software development. As a reminder, we provide economics homework help - with our experts, all numbers become easy to understand. So let's take a closer look at the event handler.

A Trivial Event Handler

A trivial event handler has code that checks for events. The main loop is common to applications. We can consider calling event listener OnKeyEnter () as an example. This code contains an argument with a character string corresponding to what the user entered before pressing the ENTER key.

Algorithm for Creating Event Handlers

The algorithm for creating event handlers includes three steps:

  • Writing a series of subroutines or methods. This step is based on the creation of special codes that will handle events and respond to them. Most often, companies provide ready-made event templates, which reduces the work time for the programmer.
  • Binding event handlers to the events themselves. If any event occurs, programmers should trigger the corresponding function. Sometimes graphic editors combine the first and second steps. Double-clicking a button allows the editor to create an event handler associated with the user clicking the button. Then it opens a text box so you can edit the event handler.
  • Writing the main loop. The essence of this function is to check for the presence of an event and call the appropriate event handler. Many companies provide ready-made main loops or tutorials on how to write the main loop. Therefore, the programmer can follow the rules or copy the template.

Exception Handlers in PL/I

An exception is thrown when the PL/I engine encounters an instruction that it cannot execute due to a runtime error. These errors will not be logged at compile-time and need to be handled at run time.

For example, if the PL/I engine receives an instruction to divide any number by "0", then the PL/I engine throws it as an exception. Therefore, the programmer needs to write an application that completely protects all users from errors. Likewise, exception handlers can be provided "ON statements" to callers to offer cleanup procedures to clean up afterward before aborting or performing restore operations and returning to the interrupted process.

Event-Driven Programming Applications

Event-driven programming is generally used in three cases:

  • When programming games in which a set of objects carries out control flow.
  • When creating server applications, it is undesirable to spawn service processes if, for one reason or another.
  • When building user interfaces, including graphical ones.

Programming languages

Different programming languages support Event-driven programming to varying degrees. The following languages have complete event support:

  • JavaScript user actions.
  • Perl events and DAEMON daemons and their PRIO priorities.
  • Delphi programming language.
  • ActionScript 3.0.
  • C # events.

The rest of the languages, for the most part, support events as exception handling.

Key Features And Characteristics Of Event-driven Programming

Below we will look at the features of event-driven programming that make it stand out from other programming methods. We also recommend contacting experienced writers who are well versed in the topic to avoid mistakes in terms. Just say "rewrite my paper," and the expert will save your text from unnecessary typos.


Service-focused is a key feature in event-driven programming used to create programs created for services, and it does not slow down the computer. The service-oriented only take in little of the computer control vitality, and usually, services run in the backdrop of OS.


In motivated event programming, time influenced is a paradigm. From the code that runs on a period trigger, time motivated can be considered a specific code that works in a particular time, which could be once one hour, once a week, or once a month. This means from the pre-set to do the activity. For example, house windows revise is the exemplary case of time motivated, which individual can establish when to revise or when to check and download the revise.

Trigger Functions

Trigger functions in event-driven coding are functions that decide on what code to perform whenever there is a specific event occurs. Programmers use these functions to select which event handler to use for the function when you can find specific event occurred.


Events include mouse, computer keyboard, and user interface, which events have to be triggered in this program. This means the user has to interact with an object in this program, for example, click a button by a mouse, use the computer keyboard to choose a button, etc.

The Simplicity of Programming and Ease of Development

Event-driven programming is simple and much more straightforward to program than another kind of programming as it's very aesthetic. For example, you can place a button by selecting it and place it onto a form and write a code for this. Event-driven development is also easy for the user to place a pre-written code script into an existing application. It allows the user to pause the code while running. Which makes expanding using event-driven programming is easy.

Event-Driven Programming vs. Object-Oriented Programming

Events can be user-generated events that arise due to user actions, system events in the operating system, and software events generated by the program. Event-driven programming is a development of the ideas of top-down design when the reactions of the program to various events are gradually determined and detailed.

Object-oriented programming brings together the best ideas embodied in structured programming and combines them with powerful new concepts to optimally organize programs. Object-oriented programming allows you to decompose a problem into its parts. Each component becomes an independent object containing its codes and data that relate to this object. In this case, the whole procedure is simplified, and the programmer can operate with much larger programs.

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