Comparing two identical strings returns false in PHP

Question

This one is completely beyond me. I'm trying to compare two strings. When I echo them, they appear to be identical, yet when I compare them with the '==' operator, it returns false. For example, when running the code below on my database. It outputs things like "APPARENTLY Apple does not equal Apple". Can anyone shed any light on this?

if ($this->data['list_text']) { //user has entered into textarea
            $list = nl2br($this->data['list_text']);

            $list_array = explode('<br />',$list);

            $ranking = 1;
            $company_array = $this->CompanyList->CompanyRanking->Company->find('list',null);

            //this is the comparison bit
            foreach ($list_array as $key => $value) {
                $companyId = null;
                foreach ($company_array as $key2 => $value2) {
                    if ($value2 != $value) {
                        echo 'APPARENTLY '.$value2.' does not equal '.$value;                           
                    } else {
                        $companyId = $key2;
                        break;
                    }
                }

                $this->data['CompanyRanking'][$ranking]['ranking'] = $ranking;
                $this->data['CompanyRanking'][$ranking]['company_id'] = $companyId;
                $ranking++;
            }
        }

Answer 1

Try var_dump() instead of echo.

echo 'APPARENTLY '.$value2.' does not equal '.$value;   
echo '<pre>Debug: ';
echo 'value='; var_dump($value);
echo 'value2='; var_dump($value2);
echo '</pre>';

It provides additional information. Eg the actual type. And the length of strings.

Answer 2

Do the strings have any extra whitespace you're not seeing? Try trimming them.

Answer 3

Try to check encoding of both string compared.

maybe it is utf8 compared with iso-5589-1 with some weird chars.

Answer 4

I agree with Olafur. I removed trim and replaced it with a preg_replace due to the fact you are assuming $value and $value2 are companyIDs. You can make a quick modification on these if the companyID is supposed to be alphanumeric, contain hyphens, etc... This version should do it:

if ($this->data['list_text']) { 
    $list = nl2br($this->data['list_text']);
    $list_array = explode('<br />', $list);

    $ranking = 1;
    $company_array = $this->CompanyList->CompanyRanking->Company->find('list',null);

    foreach ($list_array as $key => $value) {

        // remove any non digit characters
        $value = preg_replace('/[^0-9]/i','', $value); 
        $companyId = null;

        foreach ($company_array as $key2 => $value2) {

            // remove any non digit characters
            $value2 = preg_replace('/[^0-9]/i','', $value2); 

            if ($value2 != $value) {
                echo 'values not equal';                
            } else {
                $companyId = $key2;
                break;
            }
        }

        $this->data['CompanyRanking'][$ranking]['ranking'] = $ranking;
        $this->data['CompanyRanking'][$ranking]['company_id'] = $companyId;
        $ranking++;
    }
}

Answer 5

尝试trim（）用于任何空格以及var_dump（）以查看是否有其他任何东西与它一起传递。