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This chapter is from the book

Creating Random Numbers

The last function you’ll learn about in this chapter is rand(), a random-number generator. All it does is output a random number:

$n = rand(); // 31
$n = rand(); // 87

The rand() function can also take minimum and maximum parameters, if you prefer to limit the generated number to a specific range:

$n = rand (0, 10);

These values are inclusive, so in this case 0 and 10 are feasible returned values.

As an example of generating random numbers, let’s create a simple “Lucky Numbers” script.

To generate random numbers:

  1. Begin a new document in your text editor or IDE, to be named random.php (Script 4.6):
    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
       "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
    <head>
      <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
      <title>Lucky Numbers</title>
    </head>
    <body>

    Script 4.6. The rand() function generates a random number.

    1    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    2       "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    3    <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
    4    <head>
    5       <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    6       <title>Lucky Numbers</title>
    7    </head>
    8    <body>
    9    <?php // Script 4.6 - random.php
    10   /* This script generates 3 random numbers. */
    11
    12   // Address error handling, if you want.
    13
    14   // Create three random numbers:
    15   $n1 = rand (1, 99);
    16   $n2 = rand (1, 99);
    17   $n3 = rand (1, 99);
    18
    19   // Print out the numbers:
    20   print "<p>Your lucky numbers are:<br />
    21   $n1<br />
    22   $n2<br />
    23   $n3</p>";
    24
    25   ?>
    26   </body>
    27   </html>
  2. Include the PHP tags and address error management, if you need to:
    <?php // Script 4.6 - random.php
  3. Create three random numbers:
    $n1 = rand (1, 99);
    $n2 = rand (1, 99);
    $n3 = rand (1, 99);

    This script prints out a person’s lucky numbers, like those found on the back of a fortune cookie. These numbers are generated by calling the rand() function three separate times and assigning each result to a different variable.

  4. Print out the numbers:
    print "<p>Your lucky numbers
    are:<br />
    $n1<br />
    $n2<br />
    $n3</p>";

    The print statement is fairly simple. The numbers are printed, each on its own line, by using the HTML break tag.

  5. Close the PHP code and the HTML page:
    ?>
    </body>
    </html>
  6. Save the file as random.php, place it in the proper directory for your PHP-enabled server, and test it in your Web browser circle-a.jpg. Refresh the page to see different numbers circle-b.jpg.
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