如果为false，则计数为1；如果为空，则计数为false.为什么? [英] count of false gives 1 and if of an empty array gives false. why?

问题描述

我有一个只返回一行作为数组的函数.

I have a function which returns only one row as array.

我给出一个查询作为参数，该查询将只给出一行.

I give a query as a parameter which will exactly gives only one row.

function getFields($query)
{
    $t =& get_instance(); 
    $ret = $t->db->query($query);
    if(!$ret)return false;
    else if(!$ret->num_rows()) return array();
    else return $ret->row_array();
}
$ret = getFields('query string');

我以为是...

1. 如果有错误，那么我可以像if(！$ res)//echo错误一样检查它
2. 如果它是空的，我可以像if(！count($ res))//没有行一样检查它
3. 否则，我假设有一行并继续该过程...

但是

1. 出现错误时，将返回false.在if(count($ ret))给出1.
2. 如果我作为空数组返回，则if($ ret)条件失败(给出错误).

1. when there is an error false is returned. In if(count($ret)) gives 1.
2. If($ret) conditions fails (gives false) if i return as empty array.

//

$ret = getFields('query string');
if(!$fes)jerror('status,0,msg,dberror');        
if(!count($fes))jerror('status,1,msg,no rows');     
// continue execution when there atleast one row.

此代码使用ajax调用.所以我返回了一个json响应.

this code is called using ajax. so i return a json response.

为什么count为1，如果空数组为false.

why count gives 1 and if empty array gives false.

我只是想用逻辑条件进行编码，而不是提供更多的关系条件.只是为了减少代码.

我在哪里可以得到所有这些php的烦人的东西，以便可以确保自己最终不会犯上述类似的逻辑错误.

Where can i get all these BUGGING stuff of php so that i can make sure i should not end up making logical errors like the above.

BUGGING-在以上句子中 我指的不是错误，而是 事情困扰着我们.令我们着迷的东西 逻辑错误.

BUGGING - in the above sentence bugging i referred as not a bug but things bugs us. things which makes us logical errors.

---

---

我编辑了以下代码，包括以下内容，同时我得到了 https://stackoverflow的答复.com/users/451672/andrew-dunn

---

---

I edited this following code to include the following meanwhile i got this as the reply by https://stackoverflow.com/users/451672/andrew-dunn

我可以这样做，但是我仍然想知道为什么要进行上述解释

i can do it like this but still i want to know why for the above explanation

if($fes===false)jerror();
if(!$fes)jsuccess('status,4');      

推荐答案

为什么计数为1"-请参见 http://docs.php.net/count :

"why count gives 1" - see http://docs.php.net/count:

如果var不是数组，则将返回[...] 1.

If var is not an array [...] 1 will be returned.

并且如果空数组为false." -请参见 http://docs.php.net/language.types .boolean#language.types.boolean.casting :

"and if empty array gives false." - see http://docs.php.net/language.types.boolean#language.types.boolean.casting:

转换为布尔值时，以下值为FALSE:
[...]

• 具有零个元素的数组

When converting to boolean, the following values are considered FALSE:
[...]

• an array with zero elements

这篇关于如果为false，则计数为1；如果为空，则计数为false.为什么?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！