Kalkulator Sring combo

<?php
$kalimat="";
$hasil="";
$proses="";
date_default_timezone_set("Asia/Jakarta");


 if(isset($_POST["play"])){
    $kalimat=$_POST["kalimat"];
    $proses=$_POST["proses"];
    if($proses=="upper"){$hasil=strtoupper($kalimat);}

    else if($proses=="lower"){$hasil=strtolower($kalimat);}

    else if($proses=="join"){$hasil=$kalimat." dibuat Oleh Heru....";}

    else if($proses=="reverse"){
            $p=strlen($kalimat);
            $hasil="";
                    for($i=1;$i<=$p;$i++){
                    $hasil=$hasil.substr($kalimat,$p-$i,1);}}

    else if($proses=="thumbnail"){$hasil=substr($kalimat,0,1);
                                $hasil=strtoupper($hasil);
                                $p=strlen($kalimat);
                                $hasil2=substr($kalimat,1,$p-1);
                                $hasil2=strtolower($hasil2);
                                $hasil=$hasil.$hasil2;}
    else if($proses=="indexof"){$kalimat=strtolower($kalimat);
                                $cari=strstr($kalimat,"heru");
                                $p=strlen($cari);
                                if($p>0){
                                $hasil="Kalimat tsb ada kata 'heru'";}
                            else{
                                $hasil="Kalimat tsb Tidak ada kata 'heru'";}}

    else if($proses=="replace"){$hasil=str_replace("saya","heru",$kalimat);}

    else if($proses=="array"){$ar=explode(" ",$kalimat);
                            $hasil="";
                            for($i=0;$i<count($ar);$i++){
                            $hasil=$hasil.$ar[$i]." | ";}}


    else if($proses=="count"){$hasil=strlen($kalimat)." karakter";}
    else if($proses=="today"){$hasil=date("Y-m-d");}

    else if($proses=="time"){$hasil=date("H:i:s");}



    }
?>


<form name="form1" method="post" action="">
  <table width="41%" border="1" align="center" bordercolor="#FFFF00">
    <tr>
      <td colspan="3" align="center" bgcolor="#FF0000"><font color="#ffffff">Kalkulator String Combo Box</font></td>
    </tr>
    <tr>
      <td width="18%" bgcolor="#99FF33">Kalimat</td>
      <td width="3%" align="center" bgcolor="#99FF33">:</td>
      <td width="79%" bgcolor="#99FF33"><label for="kalimat"></label>
      <textarea name="kalimat" cols="35" id="kalimat"><?php echo $kalimat;?></textarea></td>
    </tr>
    <tr>
      <td bgcolor="#99FF33">Hasil</td>
      <td align="center" bgcolor="#99FF33">:</td>
      <td bgcolor="#99FF33"><b><font color="#000000"><?php echo $hasil;?></font></b></td>
    </tr>
    <tr>
      <td bgcolor="#99FF33">Combine</td>
      <td align="center" bgcolor="#99FF33">:</td>
      <td bgcolor="#99FF33"><label for="proses"></label>
        <select name="proses" id="proses">
          <option value="-">&gt;&gt;&gt;Combine&lt;&lt;&lt;</option>
          <option value="upper" <?php if($proses=="upper"){echo"selected";}?>>Upper</option>
          <option value="lower" <?php if($proses=="lower"){echo"selected";}?>>Lower</option>
          <option value="join" <?php if($proses=="join"){echo"selected";}?>>Join</option>
          <option value="reverse" <?php if($proses=="reverse"){echo"selected";}?>>Reverse</option>
          <option value="thumbnail" <?php if($proses=="thumbnail"){echo"selected";}?>>Thumbnail</option>
          <option value="indexof" <?php if($proses=="indexof"){echo"selected";}?>>Index Of</option>
          <option value="replace" <?php if($proses=="replace"){echo"selected";}?>>Replace</option>
          <option value="array" <?php if($proses=="array"){echo"selected";}?>>array</option>
          <option value="today" <?php if($proses=="today"){echo"selected";}?>>Today</option>
          <option value="time" <?php if($proses=="time"){echo"selected";}?>>Time</option>
          <option value="count" <?php if($proses=="count"){echo"selected";}?>>Count</option>
      </select></td>
    </tr>
    <tr>
      <td bgcolor="#FF0000">&nbsp;</td>
      <td bgcolor="#FF0000">&nbsp;</td>
      <td bgcolor="#FF0000"><input name="play" type="submit" id="play" value="Play"></td>
    </tr>
  </table>
</form>