[Solved] PHP switch trouble [closed]

the expression ($item>=17) && ($item<=20) evaluates to 0, as the value of $item is 0.
the switch-case statement will merely match the value of $item with case values.
So, your code, in first case is equivalent to

switch($item){
       case (1):
         $case="<16";
         break;
       case ( 0):
         $case=">=17_<=20";
         break;
       case ( 0):
         $case=">=21_<=25";
         break;
 }