How many access methods are there for variables in php?
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Description: in php, variables are divided into three access methods (scope): local variables, global variables, static variables.
1. Global variable
Description: variables defined outside the function are global variables. Normally, it can only be used outside the function. The scope is outside the function.
Sample code:
/ / the scope of the global variable $name = 'admin'; / / the global variable cannot be used inside the function because the storage location is different function user () {echo $name;} user (); / / the error cannot be reported using $name 2. Local variable
Description: the variable defined in the function is a local variable. Normally, it can only be used inside the function.
Sample code:
/ / Local variable scope $name = 'admin';echo $name;// adminfunction user2 () {$name2 =' qingyu'; / / local variable echo $name2; / / qingyu} user (); echo $name2; / / local variable cannot be used externally. Static variable
Note: normally variables are destroyed after running the current page (php's own mechanism). If you don't want to destroy, you can use static variables.
Declaration of static variables: static variable name
Sample code:
/ / static variable scope $age = 18 position variables + Echo $age; / / 19function age1 () {$age = 18; echo $age;} age1 (); / / 18function age2 () {$age = 18; echo $age; $age++;} age2 (); age2 () / / 18 18 18 function age3 () {/ / static variable declaration, the current page will not destroy the variable after the static variable declaration, but keep static $age = 18; echo $age; $age++;} age3 (); / / 18age3 (); / / 19age3 (); / / 20age3 (); / / 21age3 (); / 22 4. Global and local conversion
Description: local variables can be declared as global variables within the function, at this time the local can be used outside the function.
Manner of declaration:
$GLOBALS variable name
Global variable name
Globas $sex = 'male'; / / error reporting does not work in this way $sex = 'male'; function user () {globas $name,$sex; / / local to global, global to local $name = 'admin'; echo $sex;} user (); echo $name; is all the content of this article entitled "how many access methods are divided into variables in php". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!
