24 lines
994 B
Markdown
24 lines
994 B
Markdown
---
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title: Constants
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---
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## Constants
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Constants are a type of variable in PHP. The `define()` function to set a constant takes three arguments - the key name, the key's value, and a Boolean (true or false) which determines whether the key's name is case-insensitive (false by default). A constant's value cannot be altered once it is set. It is used for values which rarely change (for example a database password OR api key).
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### Scope
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It is important to know that unlike variables, constants ALWAYS have a global scope and can be accessed from any function in the script.
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### Example
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```PHP
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<?php
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define("freeCodeCamp", "Learn to code and help nonprofits", false);
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echo freeCodeCamp;
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```
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**Output:**
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```text
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Learn to code and help nonprofits
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```
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#### More Information:
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* <a href="https://secure.php.net/manual/en/language.constants.php" rel="nofollow">php.net constants manual</a>
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* <a href="https://secure.php.net/manual/en/function.define.php" rel="nofollow">php.net define() manual</a>
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