PHP搜索多重阵列功能始终给出TRUE值

Question

I am a newbie about this php stuff. The function below always returns true. Can you explain how this happens? My purpose was to write a general code for searching in a multiarray however I came across this problem and wondered how this can be. Kind Regards.

<?php

    function existInMultiArray ($demand, $multiarray)
    {
        foreach ($multiarray as $key => $val)
        {
            foreach($val as $key1 => $val1)
            {
                foreach($val1 as $key2 => $val2)
                {
                    if ($key == $demand)
                    {
                        return TRUE;
                    }
                    if($key1 == $demand)
                    {
                        return TRUE;
                    }
                    if ($key2 == $demand)
                    {
                        return TRUE;
                    }
                }   
            }
        }
    return FALSE;
    }


    $demand = 'asdf';
    $multiarray = array
(
    0 => array ('A' => array( 'B' => 'C')),

    1 => array ('D' => array ('E' => 'F')),

    2 => array ('G' => array ('H' => 'J')),

    3 => array ('K' => array ('L' => 'M')),

    4 => array ('N' => array ('O' => 'P')),

    5 => array ('R' => array ('S' => 'T'))
);

var_dump(existInMultiArray($demand, $multiarray)); exit;

Answer 1

This is because $key, $key1, $key2 have integer datatype and $demand have string datatype. If you compare a number with a string or the comparison involves numerical strings, then each string is converted to a number and the comparison performed numerically.

In PHP, the empty string, and the string "0" will both be equal to zero with the equality operator (==).

and in your case, you use === with strict type checking. It means it will check data type as well as value.

<?php
$demand = 'asdf';
$multiarray = array
    (
    0 => array ('A' => array( 'B' => 'C')),
    1 => array ('D' => array ('E' => 'F')),
    2 => array ('G' => array ('H' => 'J')),
    3 => array ('K' => array ('L' => 'M')),
    4 => array ('N' => array ('O' => 'P')),
    5 => array ('R' => array ('S' => 'T'))
);

function existInMultiArray ($demand, $multiarray)
{
    foreach ($multiarray as $key => $val)
    {
        foreach($val as $key1 => $val1)
        {
            foreach($val1 as $key2 => $val2)
            {
                if ($key === $demand)
                {
                    return TRUE;
                }
                if($key1 === $demand)
                {
                    return TRUE;
                }
                if ($key2 === $demand)
                {
                    return TRUE;
                }
            }   
        }
    }
    return FALSE;
}

var_dump(existInMultiArray($demand, $multiarray)); exit;
?>