Constants

Programming basics^[1]

In computer programming, a constant is an identifier with an associated value which cannot be altered by the program during normal execution – the value of the constant is, well, constant^[2].

A constant is an identifier (name) for a simple value. As the name suggests, that value cannot change during the execution of the script. A constant is case-sensitive by default. By convention, constant identifiers are always uppercase.^[3].

Constants are used when you want to prevent changes to data in a program. This usually happens in larger programs, with multiple programmers. Constants also provide a measure of security, especially in web-based applications. In lower-level languages, constants can provide more efficient use of memory than variables.

Example[edit]

Below is an example of declaring a constant in PHP:

<?php 

# this file is used to demonstrate constants in PHP

define("SCHOOL_YEAR",     "2016 - 2017");

# for the remainder of the running of this program, the value of SCHOOL_YEAR will be 2016 - 2017
# If we wanted to CALL (use) a constant, we might use the following syntax: note the lack of a $ symbol

echo "The school year is " . SCHOOL_YEAR;



?>

Standards[edit]

Define the terms: variable, constant, operator, object.

References[edit]

[1] ttp://www.flaticon.com/

[2] ttps://en.wikipedia.org/wiki/Constant_(computer_programming)

[3] ttp://php.net/manual/en/language.constants.php

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