PHP计数函数与关联数组 [英] PHP Count function with Associative Array

问题描述

有人可以向我解释count函数如何与下面的数组一起使用？

Could someone please explain to me how the count function works with arrays like the one below?

我的想法是以下代码输出4，因为有4个元素：

My thought would be the following code to output 4, cause there are 4 elements there:

$a = array 
(
  "1" => "A",
   1=> "B",
   "C",
   2 =>"D"
);

echo count($a);

推荐答案

$ c>工作正如你所期望的，eg它计算数组（或对象）中的所有元素。但是你对包含四个元素的数组的假设是错误的：

count works exactly as you would expect, e.g. it counts all the elements in an array (or object). But your assumption about the array containing four elements is wrong:

• 1等于1，因此 1 => B将覆盖1=> A。


• 因为您定义了1，下一个数字索引将为2，例如C是 2 =>当您分配 2 =>时，C

< D您覆盖了C。

• "1" is equal to 1, so 1 => "B" will overwrite "1" => "A".
• because you defined 1, the next numeric index will be 2, e.g. "C" is 2 => "C"
• when you assigned 2 => "D" you overwrote "C".

因此，您的数组将只包含 1 => B和 2 => D这就是为什么 count 给出2.你可以通过执行 print_r（$ a） / code>。这将给予

So your array will only contain 1 => "B" and 2 => "D" and that's why count gives 2. You can verify this is true by doing print_r($a). This will give

Array
(
    [1] => B
    [2] => D
)

请通过http://www.php.net/manual/en/language.types.array.php 。

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