PHP: Constants


A constant is an identifier for a simple value. The value cannot be modified during the script's execution. A valid constant name starts with a letter or underscore (no dollar($) sign before the name) and by convention constant identifier are always uppercase.

Constants are defined by using the define() function or by using the const keyword outside a class definition as of PHP 5.3.0. The name of the constant and the value must be placed within the parentheses. After defining it can never be changed or undefined. Only scalar data i.e. boolean, integer, float and string can be contained in constants.

PHP valid and invalid constant names

//Valid constants name
define("COUNTRY_NAME", "India");
define("CITYNAME", "New Delhi");
define("2NO_OF_STUDENTS", 60);

Example of a PHP constant

define("COUNTRY_NAME", "India");

Output :


View this example in browser

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PHP: Tips of the Day

PHP: How to fix error with xml2-config not found when installing PHP from sources?

All you need to do instal install package libxml2-dev for example:

sudo apt-get install libxml2-dev


sudo yum install libxml2-devel

Ref : https://bit.ly/34hOrfG