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php 学习日志- 变量作用域，变量

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Release： 2016-06-13 08:53:04
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php 学习日志- 变量作用域，变量

1、global 函数内访问全局变量

<?<span>php
</span><span>$x</span>=5<span>;
</span><span>$y</span>=10<span>;

</span><span>function</span><span> myTest()
{
</span><span>global</span> <span>$x</span>,<span>$y</span><span>;
</span><span>$y</span>=<span>$x</span>+<span>$y</span><span>;
}

myTest();
</span><span>echo</span> <span>$y</span>; <span>//</span><span> 输出 15</span>
?>
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如果myTest函数里不使用global，无法使用

PHP 将所有全局变量存储在一个名为 $GLOBALS[index] 的数组中。 index 保存变量的名称。这个数组可以在函数内部访问，也可以直接用来更新全局变量。 如$GLOBALS['y']=$GLOBALS['x']+$GLOBALS['y']

2、Static 当一个函数完成时，它的所有变量通常都会被删除。然而，有时候您希望某个局部变量不要被删除。

function myTest()
{
static $x=0;
echo $x;
$x++;
}

myTest();
myTest();
myTest();

0
1
2
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　　每次调用该函数时，该变量将会保留着函数前一次被调用时的值。该变量仍然是函数的局部变量。

Related labels：
global variables
source：php.cn
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