PHP字符串比较，===或strcmp不起作用

I have a hash map which contains certain keys which are the sorted versions of their values. For example,

$hash = array( "abc" => "cab",
               "aas" => "sas"
        );

I also have an array of sorted strings($sorted_words) and I want to compare all these strings with the keys of the above hash map and if a match is found, store the corresponding value in a string. I use === and also strcmp(), but neither works. It always says the strings didn't match. Here is my code :

foreach($sorted_words as $sc) {
    foreach($hash as $key => $value) {
        if(strcmp($sc, $key) == 0) { // or if($sc === $key)
            $string_match .= $value; // store the corresponding value for the matched key.
        }
    }
}

But the comparison fails as strcmp() always returns greater than 1 and '===' never returns true. Can anyone tell what's wrong ? I'm pretty sure there are strings that will match.

Try this :

$string_match  = "";
foreach($sorted_words as $sc) {
   if(array_key_exists($sc, $hash)){
      $string_match .=  $hash[$sc];
   }

}

When a programmer stuck, they have to start debugging

foreach($sorted_words as $sc) {
    foreach($hash as $key => $value) {
        if($sc === $key) {
            $string_match .= $value; key.
        }
        var_dump($sc, $key, $sc === $key);
    }
}

and then study the output.
This is the only way to be sure, if there are any strings that match.
While your current "pretty sure" is a mere guess.