PHP数组只返回字符串的第一个字符

Question

I'm using check-boxes to alter an SQL query.

The HTML:

        <input type="checkbox" name="chapter" value="7"  /><label>ch. 7</label><br />
        <input type="checkbox" name="chapter" value="13"  /><label>ch. 13</label>

The PHP:

   //adjust query for chapter
   $chap = $_POST['chapter'];
   $chapter = "";
   if(!empty($chap)){
        $N = count($chap);
        if($N == 1){
         $chapter .= " AND chapter = '".$chap[0]."'";
        }else{
         $chapter .= " AND (chapter = '".$chap[0]."' OR chapter = '".$chap[1]."')";
        }
   }    

       $zquery = "SELECT * FROM records WHERE ".$zipcodes.$chapter;

When the check boxes are left unchecked it works fine. When the chapter 7 box is checked it works fine. The trouble is with that 13 box. When I check that, $chap[] only returns a value of "1" instead of "13". For example, when I var_dump $zquery I get string(3384) "SELECT * FROM records WHERE (party_zip='34683' OR party_zip='34682' ) AND chapter = '1'".

Also, $N is always returning 1, even if I check both boxes. Is $_POST['chapter'] not an array? Why is it only returning the first character in the string?

Namaste

Answer 1

Both Dr. Molle and Douglas are correct, but I'd like to expand a little on their answers.

$_POST is an array. It can contain a variety of values, either in a key => value structure or in a series of values indexed numerically. Each value can be any other type of data. In this case, your variable:

$_POST['chapter']

is a string, most likely - PHP interprets the array index ([0], etc) as a character index when used against a string (or against a variable that can be trivially cast to string, like an integer or float.) This is why you're getting the first letter out instead of the first value: there's only the one value to get!

Of course, you might run into situations where the value of an array is itself an array - in which case you could access the value by typing, say, $array[0]['candles'] or something, but that's not going to happen with the $_POST array (which is always an array of strings.)