PHP class doesn't recognize this->method() -

when trying access method i've defined in php class within method in same class, following error:

parse error: syntax error, unexpected '->' (t_object_operator) in /var/www/.../toc.php on line 57

previously, i'd these functions sitting outside of class, including them needed them. having moved them one, @ first thought must having issue this user having, instance of class, can call render method file no problems. commenting out line this->printtreearray($sectionprojects); eliminates error. here's class:

<?php  class toc{      private function printtreearray($sectionprojects){         echo "var tocnodes = [\n";          //print each section, loop print each one's problems         $i = 0;         foreach($sectionprojects $sectionproject){             if($i != 0){                 echo ",\n";             }              $project = $sectionproject->getproject();             //get due date mouseover text             $due = $project->getduedate('f js, y h:i a');              $q = new projectproblemquery();             $projectproblems = $q->findbyrelprojectid($project->getid());              $pid = $i + 1;             echo "{id: $pid, pid: 0, name: \"project $pid\", title: \"due: $due\", isparent: true, open: true}";              //print section's problem list             $probid = 1;             foreach($projectproblems $projectproblem){                 echo ",\n";                  $nodeid = ($pid * 10) + $j;                  echo "{id: $nodeid, pid: $pid, name: \"$pid.$probid\", url: \"#\", target: \"_top\"}";                  $j++;             }              $i++;         }         echo"];\n";     }      public function render($section){         if(! $section instanceof section){             echo "$section not instance of section!";         }         else{             echo "<ul id=\"toctree\" class=\"ztree\"></ul>\n";              echo "<script type=\"text/javascript\">\n";              $sectionprojects = $section->getsectionprojects();              this->printtreearray($sectionprojects);              echo "$(document).ready(function () {                     $.fn.ztree.init($(\"#toctree\"), setting, tocnodes);                 });";             echo "</script>";         }     }   } 

this first time asking question on - i've been able find answers coding dilemmas, 1 has me baffled. realize there's lot of not-elegant stuff going on in class, if there's point of style can use avoid sort of error in future, i'd appreciate getting learn it.

you should use $this instead of this.