Question

我试图在每次调用函数时都这样做，它应该返回两倍于这样的数字：

calls(); // NULL
calls(); // 2
calls(); // NULL
calls(); // 4

这是我的代码：

function calls() {
    if (NULL) {
        return NULL;
    }
    else {
        $calls++;
        return $calls;
    }
}


calls(); // NULL
calls(); // 2
calls(); // NULL
calls(); // 4

Answer 1

不要使用全局变量，在相关函数中使用static变量：

function count_calls() {
     static $count = 0;
     ++$count;
     return ($count % 2 === 0) ? $count : NULL ; 
}

Answer 2

以下是您应该做的例子：

$current = 0;
$current = calls($current); // NULL
echo display($current);
$current = calls($current); // 2
echo display($current);
$current = calls($current); // NULL
echo display($current);
$current = calls($current); // 4
echo display($current);

/**
* Do stuff for your call with in param your last call pointer and returns new pointer
**/
function calls($last) {
     return $last++;
}

/**
* Returns null if not even, else the pointer value
**/
function display($value){

    if ($value % 2 = 0)
         return $value;
    return null;
}

当然，如果你将当前指针存储在$ this-＆gt;当前内容中，对象会更容易，但是我不认为你所显示的代码在适当的时候被你的理解所占用！好好玩吧

$class = new Call();
$class->calls();
echo $class->display();
$class->calls();
echo $class->display();
$class->calls();
echo $class->display();
$class->calls();
echo $class->display();
    class Call {

        private $current = 0;

        /**
        * Do stuff for your call with in param your last call pointer and returns new pointer
        **/
        function calls() {
             $this->current++:
             return $this->current;
        }

        /**
        * Returns null if not even, else the pointer value
        **/
        function display(){

            if ($this->current % 2 = 0)
                 return $this->current;
            return null;
        }
    }

Answer 3

检查此代码：

$calls = 0;

function calls() {
    $GLOBALS['calls']++;
    if ($GLOBALS['calls'] % 2 != 0) {
        return NULL;
    }
    else {
        //$GLOBALS['calls']++;
        return $GLOBALS['calls'];
    }
}


var_dump(calls()); // NULL
var_dump(calls()); // 2
var_dump(calls()); // NULL
var_dump(calls()); // 4

php - 每次调用函数时返回两次

3 个答案: