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The difference between global variables global and $GLOBALS[] in PHP_PHP Tutorial

WBOY
Release： 2016-07-13 10:55:55
Original
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PHP’s global variables are a little different from C language. In C language, global variables automatically take effect in functions unless covered by local variables. This can cause problems, as someone might carelessly mutate a global variable. Global variables in PHP must be declared as global using global when used in functions.

1. Comparison with examples
Example 1:

The code is as follows
 代码如下 复制代码
$var1 = 1;
function test(){
unset($GLOBALS['var1']);
}
test();
echo $var1;
?>  
Copy code
$var1 = 1;

function test(){
代码如下 复制代码
$var1 = 1;
function test(){
global $var1;
unset($var1);
}
test();
echo $var1;
?>
                                                                unset($GLOBALS['var1']); } 

test();
echo $var1;

?>





Because $var1 was deleted, nothing is printed.

Example 2:

function test(){
The code is as follows
 Copy code
$var1 = 1;
global $var1;

              unset($var1);                                             } 

test();

echo $var1;
Related labels：
global php different overall situation the difference variable and have of language
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