string - strpos function issue in PHP not finding the needle -

in php have open .php file , want evaluate lines. when $table_id , $line variables assigned value.

within text file have:

...   $table_id = 'crs_class';                      // table name $screen   = 'crs_class.detail.screen.inc';    // file identifying screen structure ... 

amongst other lines. if statement below never detects occurance of $table_id or $screen (even without $ prepended). can't understand why won't work strpos statement below looking 'require' works fine.

so, why isn't if statement getting hit?

while ($line=fgets($fh)) {     //echo "evaluating... $line <br>";     **if ((($pos = stripos($line, '$table_id')) === true) || (($pos = stripos($line, '$screen'))===true))**     {         // todo: not evaluating tableid , screen lines correctly fix.         // set $table_id , $screen variables task scripts         eval($line);     }      if (($pos=stripos($line, 'require')) === true) {          $controller = $line;     } } 

use !==false instead of ===true
stripos returns position integer if needle found. , that's never ===bool.
might interested in php's tokenizer module or lexer package in pear repository.