what is a event

Question

i am wondering about some things related to computer programming.

Answer 1

"In computing, an event is an action or occurrence recognized by software that may be handled by the software. Computer events can be generated or triggered by the system, by the user or in other ways. Typically, events are handled synchronously with the program flow, that is, the software may have one or more dedicated places where events are handled, frequently an event loop. A source of events includes the user, who may interact with the software by way of, for example, keystrokes on the keyboard. Another source is a hardware device such as a timer. Software can also trigger its own set of events into the event loop, e.g. to communicate the completion of a task. Software that changes its behavior in response to events is said to be event-driven, often with the goal of being interactive."   -  Wikipedia

 

Examples:

  --  event triggered by the system:  "File not found."

  --  event triggered by the user:     Clicked on "Refresh"

  --  event triggered by the hardware (e.g., timer):      "Timeout."

 

In many cases, events may occur at any time, independent of the progress of a program.  They may be handled, then allow the program to resume computing where it was interrupted (thus, events may be "interrupts;"  see interrupt-driven systems).

 

Answer 2

 

An event is something that might happen external to your running program.  For example, a mouse click, or key pressed on the keyboard.  Other things can be events too, like messages from other running threads or programs, external sensors, etc.