Questions about global! Solution

Questions about global! I found that many programs, such as dede, all like to declare a global variable in a function, but I have searched the whole site and have not seen a globally variable with the same name defined by the outside. for example: functionSetVar ($ k, $ v) {global $ _ vars; questions about global!
I found that many programs, including dede, all like to declare a global variable in a function, but I have searched the entire site and have not seen external defined global variables of the same name,

For example:


Function SetVar ($ k, $ v)
{
Global $ _ vars;
If (! Isset ($ _ vars [$ k])
{
$ _ Vars [$ k] = $ v;
}
}

Function GetVar ($ k)
{
Global $ _ vars;
Return isset ($ _ vars [$ k])? $ _ Vars [$ k]: '';
}

Here $ _ vars; is defined for the first time in the SetVar function, whether it means that a global variable has been defined here, and the following GetVar function

Is $ _ var the same global variable as $ _ var in other places?

What does this mean?





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If this variable is not in global, it will be created as a global variable.
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A variable is declared as global. the variable remains unique throughout the project!
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It is usually defined on the portal page or the page where variables are uniformly defined.

This is a declaration, not a definition. All php variables may become global variables.
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Discussion
I found that many programs, including dede, all like to declare a global variable in a function, but I have searched the entire site and have not seen external defined global variables of the same name,

For example:


Function SetVar ($ k, $ v)
{
Global $ _ vars;
If (! Isset ($ _ vars [$ k])
{
$ _ Vars [$ k] = $ v;
}
}

Function GetVar ($ k ......