Creating a random number once and keeping it

bgs · 02-14-2012, 04:35 PM

Hi,

I'm just beginning to learn PHP (day 2) and I can't really seem to figure this one out. My idea is a simple number guessing game that works something like this:

$num = rand(0,100);

(Accept $guess from user input)

if $num < $guess echo 'too low' etc.

The form references itself and sends the guess via POST. My problem is that the random number is getting set each time. I come from a forms/console development background and this is the first time I've delved into web programming, so there's some element here regarding the 'session' that isn't quite straight in my head.

Please feel free to enlighten me, poke fun at my code, etc.! Thanks for your help.

This is my code. It's almost entirely lifted from "Sams Teach Yourself PHP, MySQL and Apache" but I've modified the functionality to attempt to use a random number.

Code:

<?php
	$num = rand(0,100);
	if (!isset($_POST["guess"]))
	{
		$message = "What number am I thinking of?";
	}
	else if ($_POST["guess"] > $num)
	{
		$message = "Too high, guess again!";
	}
	else if ($_POST["guess"] < $num)
	{
		$message = "Too low, guess again!";
	}
	else
	{
		$message = "Correct!";
	}
?>

<html>
<head><title>Number guess</title></head>
<body>
<?php echo $message ?>
<form action="<?php echo $_SERVER["PHP_SELF"]; ?>" method="POST">
<input type="text" name="guess" />
<p><input type="submit" value="Submit"/></p>
</form>
<?php echo $num ?> <!-- just so I can see the output -->
</body>
</html>

bgs · 02-14-2012, 05:03 PM

Well, I've fixed it by using a hidden input and passing the value along via POST. Here's the working code:

Code:

<?php

	if (!isset($_POST["guess"]))
	{
		$message = "What number am I thinking of?";
		$num = rand(0,100);
	}
	else
	{
		$num = $_POST['num'];
		if ($_POST["guess"] > $num)
		{
			$message = "Too high, guess again!";
		}
		else if ($_POST["guess"] < $num)
		{
			$message = "Too low, guess again!";
		}
		else
		{
			$message = "Correct!";
		}
}
?>

<html>
<head><title>Number guess</title></head>
<body>
<?php echo $message ?>
<form action="<?php echo $_SERVER["PHP_SELF"]; ?>" method="POST">
<input type="text" name="guess"/>
<input type="hidden" name="num" value="<?php echo $num ?>" />
<p><input type="submit" value="Submit"/></p>
</form>
<?php echo $num ?>
</body>
</html>

tony · 02-15-2012, 04:50 AM

The thing about web development is that it is stateless due to the nature of http requests. Meaning that you can't save state between requests (for example when you submit a form or click on a link). There is a few things you can do here to save the random number between requests, you can use a cookie to save it and then obtain it later, another would be using sessions (which sometimes are implemented using cookies). The cookies are saved on the client while the sessions are most of the time saved in client and sometimes in server. But on the server side you can also save it in a database or a local file.

Or you can also use the hidden input tag to keep it in the between requests.

The next is an example of how it would look using the hidden input. Just gotta make sure the

PHP Code:

<?php
$message = "What number am I thinking of?";
$num = $_POST['num'] ? $_POST['num'] : rand(0,100);
if (isset($_POST["submit"])) {
  $num = $_POST['num'];
  if ($_POST['guess'] > $num) {
    $message = "Too high, guess again!";
  } elseif ($_POST['guess'] < $num) {
    $message = "Too low, guess again!";
  } else {
    $message = "Correct!";
  }
}
?>

<html>
<head><title>Number guess</title></head>
<body>
<?php echo $message ?>
<form action="<?php echo $_SERVER["PHP_SELF"]; ?>" method="POST">
<input type="text" name="guess"/>
<input type="hidden" name="num" value="<?php echo $num ?>" />
<p><input type="submit" name="submit" value="Submit"/></p>
</form>
<?php echo isset($_POST['submit']) ? $num : ''; ?>
</body>
</html>

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