The role of the php keyword global in defining variables

PHPIf the keyword global is used inside a function, it means that the variable used in this function is global, and global variables can work in the entire page. For example,

$conf = 1;  
function conf_test() {  
global $conf;  
return ++$conf;  
}  
echo conf_test()."< br>";  
echo conf_test()."< br>";

output:

2
3

If there is no global $conf;, the output will be all 1. The role of the PHP keyword global is to declare in function that the $conf used within this function is not local, but globally available. In other words, the $conf defined inside the function is not a variable within the function, but the $conf defined outside the function (that is, $conf = 1;). In fact, if $GLOBALSarray## is used here #, it is easier to understand.

When we declare a variable $conf on the page, it is actually equivalent to defining an item $GLOBALS['conf'] in the $GLOBALS array. And this $GLOBALS is globally visible. So the above code is written in $GLOBALS format as

$conf = 1;  
function conf_test() {  
return ++$GLOBALS['conf'];  
}  
echo conf_test()."<br>";  
echo conf_test()."<br>";

Output:

2
3

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