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 create a newline character?

Only double quoted strings interpret the escape sequences \r and \n as '0x0D' and '0x0A' respectively, so you want:


Single quoted strings, on the other hand, only know the escape sequences \\ and \'.

So unless you concatenate the single quoted string with a line break generated elsewhere (e. g., using double quoted string "\r\n" or using chr function chr(0x0D).chr(0x0A)), the only other way to have a line break within a single quoted string is to literally type it with your editor:

$s = 'some text before the line break
some text after';

Make sure to check your editor for its line break settings if you require some specific character sequence (\r\n for example).

Ref : https://bit.ly/3hcyege