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PHP中Global和Local范围以及Static变量

程序员文章站 2022-05-02 08:42:08
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1. Local scope

function update_counter()

{

$counter++;//此处$counter为局部变量,与函数外的$counter非同一个

}

$counter = 10;

update_counter();

echo $counter;

//输出:10

2. Global scope

function update_counter()

{

global $counter;//利用global关键字在函数内进行声明即可获取全局域的$counter

$counter++;

}

$counter = 10;

update_counter();

echo $counter;

//输出: 11

function update_counter()

{

$GLOBALS[counter]++;

}

$counter = 10;

update_counter();

echo $counter;

//输出:11

3. Static variables

function update_counter()

{

static $counter = 0;//利用static关键字进行声明$counter,具有局部域

$counter++;

echo "Static counter is now $counter\n";

}

$counter = 10;

update_counter();

update_counter();

echo "Global counter is $counter\n";

/*输出:

Static counter is now 1

Static counter is now 2

Global counter is 10

*/