![]() |
< Day Day Up > |
![]() |
9.4 Displaying a CalendarThis section puts the date and time functions to work in displaying a calendar. The show_form( ) function in Example 9-17 displays a form that asks for a month and year. The process_form( ) function hands those values off to the show_calendar( ) function, which does the real work of printing a calendar grid for a particular month. The structure of the if( ) statement that controls show_form( ), validate_form( ), and process_form( ) is different in Example 9-17 than in previous form examples. That's because we want to display the form above the calendar. Usually, if the form data is valid, show_form( ) is not called—only process_form( ) is. But here, show_form( ) is called before process_form( ) so that the form is displayed above the calendar and the user can pick another month and year to view. Similarly, the call to show_form( ) that happens when the form has not been submitted (when there is no $_POST['_submit_check'] parameter) is followed by a call to show_calendar( ) to display the calendar for the current month the first time the page is loaded. Example 9-17. Printing a calendar<?php // Use the form helper functions defined in Chapter 6 require 'formhelpers.php'; $months = array(1 => 'January', 2 => 'February', 3 => 'March', 4 => 'April', 5 => 'May', 6 => 'June', 7 => 'July', 8 => 'August', 9 => 'September', 10 => 'October', 11 => 'November', 12 => 'December'); $years = array( ); for ($year = date('Y') - 1, $max_year = date('Y') + 5; $year < $max_year; $year++) { $years[$year] = $year; } if ($_POST['_submit_check']) { if ($errors = validate_form( )) { show_form($errors); } else { show_form( ); process_form( ); } } else { // When nothing is submitted, show the form and then // a calendar for the current month show_form( ); show_calendar(date('n'), date('Y')); } function validate_form( ) { global $months, $years; $errors = array( ); if (! array_key_exists($_POST['month'], $months)) { $errors[ ] = 'Select a valid month.'; } if (! array_key_exists($_POST['year'], $years)) { $errors[ ] = 'Select a valid year.'; } return $errors; } function show_form($errors = '') { global $months, $years, $this_year; // If the form is submitted, get defaults from submitted variables if ($_POST['_submit_check']) { $defaults = $_POST; } else { // Otherwise, set our own defaults: the current month and year $defaults = array('year' => date('Y'), 'month' => date('n')); } if ($errors) { print 'You need to correct the following errors: <ul><li>'; print implode('</li><li>',$errors); print '</li></ul>'; } print '<form method="POST" action="'.$_SERVER['PHP_SELF'].'">'; input_select('month', $defaults, $months); input_select('year', $defaults, $years); input_submit('submit','Show Calendar'); print '<input type="hidden" name="_submit_check" value="1"/>'; print '</form>'; } function process_form( ) { show_calendar($_POST['month'], $_POST['year']); } function show_calendar($month, $year) { global $months; $weekdays = array('Su', 'Mo', 'Tu', 'We', 'Th', 'Fr', 'Sa'); // Find the epoch timestamp for midnight on the first day of the month $first_day = mktime(0,0,0,$month, 1, $year); // How many days are in the month? $days_in_month = date('t', $first_day); // What day of the week (numerically) is the first day of the month? // You need this to put the first table cell in the right place $day_offset = date('w', $first_day); // Print the table header and the row of weekday names print<<<_HTML_ <table border="0" cellspacing="0" cellpadding="2"> <tr><th colspan="7">$months[$month] $year</th></tr> <tr><td align="center"> _HTML_; print implode('</td><td align="center">', $weekdays); print '</td></tr>'; // If the first day of the month is, say, a Tuesday, then you // need to put blank table cells under "Su" and "Mo" in the first // row so that the day 1 table cell goes under "Tu" if ($day_offset > 0) { for ($i = 0; $i < $day_offset; $i++) { print '<td> </td>'; } } // Print a table cell for each day of the month for ($day = 1; $day <= $days_in_month; $day++ ) { print '<td align="center">' . $day . '</td>'; $day_offset++; // If this cell was the seventh in the row, then // end the table row and reset $day_offset if ($day_offset = = 7) { $day_offset = 0; print "</tr>\n"; // If there are more days to come, then // start a new table row if ($day < $days_in_month) { print '<tr>'; } } } // At this point, one table cell has been printed for each day // of the month. If the last day of the month isn't a Saturday // then the last row of the table needs to be padded with // some blank cells out to the end of the row if ($day_offset > 0) { for ($i = $day_offset; $i < 7; $i++) { print '<td> </td>'; } print '</tr>'; } print '</table>'; } ?> In October 2004, Example 9-17 produces a page that looks like Figure 9-2. Figure 9-2. Calendar form and display![]() |
![]() |
< Day Day Up > |
![]() |