Why doesn't this array search work for me?

I have a simple array search I'm doing with php.

$qs = 'something$';

// check if string has bad characters...
$bad_chars = array('$',',',' ','?','=','&','-','|','@','#','%','^','*','(',')','{','}','|','\\','[',']','/','`','~');

if(in_array($qs,$bad_chars)) {
  echo 'bad characters';
}

To me, th开发者_运维知识库is should echo 'bad characters', but it doesn't.

What am I missing?

UPDATE: benchmark, comparing the 4 answers with code:

100,000 iterations over the test_bad_charachters function, no output:

Jason's answer (for/str/in_array): 32 sec
Mike Lewis' answer (foreach/str_split/in_array): 23 sec
Gaurav's answer (array_intersect/!=): 8 sec
my answer (str_replace/==): 4 sec

UPDATE END

as the other answers point out, in_array($qs, $bad_chars) does not test if the characters of $qs are in $bad_chars, but the whole string $qs (which obviously it is not). to get the expected result, you have to test the single characters of $qs.

here is a solution that should do this fast:

<?php
$qs = 'something$';

// bad characters
$bad_chars = array('$',',',' ','?','=','&','-','|','@','#','%','^','*','(',')','{','}','|','\\','[',']','/','`','~');

// replace all bad characters in $qs with \00. if the resulting string 
// differs from the original string, it has bad characters.
// using a single call to str_replace should make this faster than all 
// other suggested solutions - see the benchmark in the UPDATE.
if (str_replace($bad_chars, '\0', $qs) == $qs) {
  echo 'bad characters';
}

$array = str_split($qs);

if(array_intersect($array, $bad_chars) != array())
{
    echo 'bad characters';
}

Just look at each letter individually instead of the word as a whole.

$qs = 'something$';

$bad_chars = array('$',',',' ','?','=','&','-','|','@','#','%','^','*','(',')','{','}','|','\\','[',']','/','`','~');

for($i=0; $i < strlen($qs); $i++) {
 // check if string has bad characters...
 if(in_array($qs[$i],$bad_chars)) {
  echo 'bad characters';
 }
}

This is because it is seeing if "something$" is an element in $bad_chars, which it isn't.

Edit:

Solution:

<?php
$qs = 'something$';

// check if string has bad characters...
$bad_chars = array('$',',',' ','?','=','&','-','|','@','#','%','^','*','(',')','{','}','|','\\','[',']','/','`','~');

foreach(str_split($qs) as $char){

  if(in_array($char, $bad_chars)){

    echo $char. " was bad char";
  }
}

?>

you are searching for the full "something$"', not just the bad "$" - this is why.

look for doc in http://php.net/in_array .