<?php 
  $array = explode(" ", $_POST["Rechnung"]);
  
    $zahl = array();
    $operator = array();
    $erg = real;
    $z = int;
    $o = int;
    
    $z = 0;
    $o = 0;
  
  for($i=0; $i<count($array); $i++){
    echo $array[$i];
    
    if(is_int($array[$i])){
      $zahl = array_push($zahl, $array[$i]);
      $z = $z + 1;
    }else{
  
    switch($array[$i]){
      case "+":
        $operator = array_push($operator, $array[$i]);
        if(is_int($array[$i+1])){
          $erg = $zahl[$z] + $array[$i+1];
        }else{
          echo "nix da";
        }
      break;
      case "-":
        $operator = array_push($operator, $array[$i]);
      break;
      case "*":
        $operator = array_push($operator, $array[$i]);
        if(is_int($array[$i+1])){
          $erg = $zahl[$z] * $array[$i+1];
        }else{
          echo "nix da";
        }
      break;
      case "/":
        $operator = array_push($operator, $array[$i]);
      break;
      case "(":
        $operator = array_push($operator, $array[$i]);
      break;
      case ")":
        $operator = array_push($operator, $array[$i]);
      break;
      case "sin(":
        $operator = array_push($operator, $array[$i]);
      break;
      case "cos(":
        $operator = array_push($operator, $array[$i]);
      break;
      case "tan(":
        $operator = array_push($operator, $array[$i]);
      break; 
      $o = $o + 1;
    }
    }


  }
  echo "=";  
?>

 5+nix da3*
Warning: array_push() [function.array-push]: First argument should be an array in D:\Programme\Programmieren\PHP\apachefriends\xampp\htdocs\Kellerautomat.php on line 43
nix da26=