In computer programming, command refers to an instruction to the computer to perform a specific task. Every program interacting with a human programmer responds to set of commands. The procedure of entering a set of commands and the syntax is called user interface. There are different forms of commands. For example, programmer inputs special keywords for the program to understand. The keywords work as commands. Another example of a command is the graphics object on the screen. A web page development expert adds various buttons or graphical objects on the screen for users to click on it, thus triggering an action.
With the EVAL command can work with data not known at load time (example: a user entered data). It takes any string provided by programmers and executes it by returning a result, if applicable. Programmers in websites development firm use this command in a variety of activities. For example, a list of field names can be reduced to a simple array and loop using the EVAL command.