How to set value of input field by php variable’s value

PHP – Set value in HTML-Form

echo "<input name="Titel" type="text" size="30" value="<?php echo $alben[$i]['Titel']; ?>">";

you need escape the quotes and remove the 2nd echo

echo "<input name=\"Titel\" type=\"text\" size=\"30\" value=\"" . $alben[$i]['Titel'] . "\">";

We have a simple php calculator which code is:

<html>
 <head>
 <title>PHP calculator</title>
 </head>

<body bgcolor="orange">
<h1 align="center">This is PHP Calculator</h1>
<center>
<form method="post" action="phptest.php">
Type Value 1:<br><input type="text" name="value1"><br>
Type value 2:<br><input type="text" name="value2"><br>
Operator:<br><input type="text" name="sign"><br>
Result:<br><input type"text" name="result">
<div align="center"><input type="submit" name="submit" value="Submit"></div>

</form>
</center>

<?php
 if(isset($_POST['submit']))
 {
 $value1=$_POST['value1'];
 $value2=$_POST['value2'];
 $sign=$_POST['sign'];

if($value1=='') {
 echo "<script>alert('Please Enter Value 1')</script>";
 exit();
 }

if($value2=='') {
 echo "<script>alert('Please Enter Value 2')</script>";
 exit();
 }

if($sign=='+') {
 echo "Your answer is: " , $value1+$value2;
 exit();
 }

if($sign=='-') {
 echo "Your answer is: " , $value1-$value2;
 exit();
 }

if($sign=='*') {
 echo "Your answer is: " , $value1*$value2;
 exit();
 }

if($sign=='/') {
 echo "Your answer is: " , $value1/$value2;
 exit();
 }


}
?>

All I want to do is that answer should be displayed in the result input field instead of echoing them separately. Please help? I Know its simple but I am new in PHP.

Answer: One way to do it will be to move all the php code above the HTML, copy the result to a variable and then add the result in the <input type=”text” /> tag.
Try this –

<?php
//Adding the php to the top.
if(isset($_POST['submit']))
{
 $value1=$_POST['value1'];
 $value2=$_POST['value2'];
 $sign=$_POST['sign'];
 ...
 //Adding to $result variable
 if($sign=='-') {
 $result = $value1-$value2;
 }
 //Rest of your code...
}
?>
<html>
<!--Rest of your tags...-->
Result:<br><input type"text" name="result" value = "<?php echo (isset($result))?$result:'';?>">