Constants in PHP
By: Andi, Stig and Derick in PHP Tutorials on 2008-11-22
In PHP, you can define names, called constants, for simple values. As the name implies, you cannot change these constants once they represent a certain value. The names for constants have the same rules as PHP variables except that they don't have the leading dollar sign. It is common practice in many programming languages - including PHP - to use uppercase letters for constant names, although you don't have to. If you wish, which we do not recommend, you may define your constants as case-insensitive, thus not requiring code to use the correct casing when referring to your constants.
Tip: Only use case-sensitive constants both to be consistent with accepted coding standards and because it is unclear if case-insensitive constants will continued to be supported in future versions of PHP.
Unlike variables, constants, once defined, are globally accessible. You don't have to (and can't) redeclare them in each new function and PHP file.
To define a constant, use the following function:
define("CONSTANT_NAME", value [, case_sensitivity])
Where:
- "CONSTANT_NAME" is a string.
- value is any valid PHP expression excluding arrays and objects.
- case_sensitivity is a Boolean (true/false) and is optional. The default is true.
An example for a built-in constant is the Boolean value true, which is registered as case-insensitive.
Here's a simple example for defining and using a constant:
define("MY_OK", 0);
define("MY_ERROR", 1);
...
if ($error_code == MY_ERROR) {
print("There was an error\n");
} Add Comment
This policy contains information about your privacy. By posting, you are declaring that you understand this policy:
- Your name, rating, website address, town, country, state and comment will be publicly displayed if entered.
- Aside from the data entered into these form fields, other stored data about your comment will include:
- Your IP address (not displayed)
- The time/date of your submission (displayed)
- Your email address will not be shared. It is collected for only two reasons:
- Administrative purposes, should a need to contact you arise.
- To inform you of new comments, should you subscribe to receive notifications.
- A cookie may be set on your computer. This is used to remember your inputs. It will expire by itself.
This policy is subject to change at any time and without notice.
These terms and conditions contain rules about posting comments. By submitting a comment, you are declaring that you agree with these rules:
- Although the administrator will attempt to moderate comments, it is impossible for every comment to have been moderated at any given time.
- You acknowledge that all comments express the views and opinions of the original author and not those of the administrator.
- You agree not to post any material which is knowingly false, obscene, hateful, threatening, harassing or invasive of a person's privacy.
- The administrator has the right to edit, move or remove any comment for any reason and without notice.
Failure to comply with these rules may result in being banned from submitting further comments.
These terms and conditions are subject to change at any time and without notice.
- Data Science
- Android
- React Native
- AJAX
- ASP.net
- C
- C++
- C#
- Cocoa
- Cloud Computing
- HTML5
- Java
- Javascript
- JSF
- JSP
- J2ME
- Java Beans
- EJB
- JDBC
- Linux
- Mac OS X
- iPhone
- MySQL
- Office 365
- Perl
- PHP
- Python
- Ruby
- VB.net
- Hibernate
- Struts
- SAP
- Trends
- Tech Reviews
- WebServices
- XML
- Certification
- Interview
categories
Related Tutorials
Send push notifications using Expo tokens in PHP
PHP convert string to lower case
A Basic Example using PHP in AWS (Amazon Web Services)
Different versions of PHP - History and evolution of PHP
PHP code to write to a CSV file for Microsoft Applications
PHP code to write to a CSV file from MySQL query
PHP code to import from CSV file to MySQL
Password must include both numeric and alphabetic characters - Magento
Resume or Pause File Uploads in PHP
PHP file upload prompts authentication for anonymous users
PHP file upload with IIS on windows XP/2000 etc
Comments