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The usage of global in php is: 1. If you use global to declare, you can call variables outside the function; 2. Introduce the [$mk] variable outside the function, and global will be globalized here. The meaning of the variable.
The usage of global in php is:
To introduce a variable in java, it can be passed in the form of parameters , because Java uses object-oriented programming, but there are a lot of process-oriented things in PHP. For example, when an external variable is introduced into a function, under normal circumstances, this external variable is not passed in through parameters. , but introduced directly through global. But this global does not mean globalization. It is a test of the code.
$mk ="Test value"; <br> function initValue() <br> { <br> $va =$mk; <br> echo $va; <br> } <br><br>
The running result is:
- Undefined variable: mk
Because $mk
is only defined in the method , so it is a different variable from $mk
defined before the method. $mk
has no value assigned, so an error is reported.
If it is declared with global, you can call variables outside the function.
$mk ="Test value"; <br> function initValue() <br> { <br> global $mk; <br> $va =$mk; <br> echo $va; <br> } <br> initValue(); <br>
The running result is: Test value. Here, global is used to introduce the $mk
variable outside the function.
In order to test global, here There is no meaning of globalizing variables, so I did another test.
$mk ="Test value"; <br> function initValue() <br> { <br> global $mk; <br> $va =$mk; <br> echo $va; <br> } <br> function initValue2() <br> { <br> $vc =$mk; <br> echo $vc; <br> } <br> initValue(); <br> initValue2(); <br>
The running results are: Test value and - Undefined variable: mk, which shows that even if global is used, it is only valid in a function, so the global here is just to introduce the upper variable
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