意外转换为布尔值? [英] unexpected cast to boolean?

问题描述

输入以下内容: http://example.com/item.php? room = 248& supply_id = 18823 ，以下2个块应该产生相同的结果.他们为什么不呢?除了咖啡，我还想念什么?

Given this input: http://example.com/item.php?room=248&supply_id=18823, the following 2 blocks ought to produce the same result. Why don't they? What am I missing other than coffee?

此块给出了期望值:

if (isset($_GET['supply_id']) && isset($_GET['room'])) {
    $id=validkey($_GET['supply_id']); //18823
    $room=validkey($_GET['room']); //248
    $arr=array('s'=>$id,'r'=>$room); //s=>18823, r=>248
}

但是如果我一步完成检查和赋值，$ id最终等于1而不是18823.为什么?

But if I do the check and the assignment in one step, $id ends up equal to 1 instead of 18823. Why?

if (isset($_GET['supply_id']) && isset($_GET['room'])) {
    if($id=validkey($_GET['supply_id']) && $room=validkey($_GET['room'])) 
        $arr=array('s'=>$id",'r'=>$room); //s=>1, r=>248
}

这是我正在使用的功能:

This is the function I'm using:

function validkey($value){
    if(is_scalar($value)){
        $value=(int)$value;
        return ($value>0) ? $value : false;
    }
    return false;
}

推荐答案

您应该使用括号:

if(($id=validkey($_GET['supply_id'])) && ($room=validkey($_GET['room']))) 

否则，将validkey($_GET['supply_id']) && $room=validkey($_GET['room'])的结果分配给$id变量，因为&&运算符的优先级高于=

Otherwise the result of validkey($_GET['supply_id']) && $room=validkey($_GET['room']) is assigned to $id variable because && operator has higher precedence than =

这篇关于意外转换为布尔值?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！