Detailed introduction to php variable scope

After a variable is defined, by default, it can be used within the function, but not outside the function.

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• Variables can only be used within their scope. This scope is called the variable's scope. Scope

• Variables defined in a function are called local variables

• Variables defined outside the function are called global variables

Code example:

function test (){
    $sum = 36; //局部变量
    return $sum;
}
$sum = 0;	//全局变量
echo text();	//输出结果：36
echo $sum;	//输出结构：0

So how to use global variables in functions?

Parameter passing, global keyword and super global variable $GLOBALS.

Code example:

$snap = 'nihao';
function abc(){
 global $snap;//全局变量的关键词，通常加在变量前。引用全局变量
 return $GLOBALS['snap'];//引用外部变量。定义全局变量
}
echo abc();

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