Notes for some basic PHP knowledge

What are some basic PHP knowledge records? PHPdefine () function? Define and use the define () function to define a constant. Constants are similar to Variables. The difference is that, after a constant is set, the constant value cannot change the dollar sign ($) that does not need to begin with the constant name) the scope does not affect constant access. the constant value can only be a string or number syntax :? De PHP basic knowledge record

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PHP define () function

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Definition and usage

The define () function defines a constant.

Constants are similar to variables, except that:

• After setting, the constant value cannot be changed.
• The constant name does not need to start with the dollar sign ($)
• The scope does not affect constant access.
• A constant value can only be a string or number.

Syntax:

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define(name,value,case_insensitive)

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Parameter description

Name	Required. Specifies the name of a constant.
Value	Required. Specifies the value of a constant.
Case_insensitive	Optional. Specifies whether the constant name is case sensitive. If it is set to true, it is not case sensitive. The default value is false (case sensitive ).

Example 1

Defines a case-sensitive constant:

 define("GREETING","Hello world!");echo constant("GREETING");?>

Output:

Hello world!

Example 2

Defines a case-insensitive constant:

 define("GREETING","Hello world!",TRUE);echo constant("greeting");?>

Output:

Hello world!

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