A brief analysis of how to use PHP to implement a simple calendar program? (with code)

How to use PHP to implement a simple calendar program? This article uses a code example to help you understand how to use PHP to implement a simple calendar program. I hope it will be helpful to you.

Speaking of processing dates and times, we must introduce the writing of calendar programs. Most readers may think that the function of the calendar is only to display the current date on the page. In fact, this is not the case. The calendar is in our plays a more important role in development. For example, when we develop a "notepad", we need to set the date through the calendar. In addition, in some systems, we need to use the calendar to arrange tasks by date, etc.

There are not many date and time functions involved in the examples in this section. They are all introduced before. The main purpose is to consolidate the object-oriented and time function applications introduced earlier by writing a calendar class. At the same time, the examples involve some For front-end knowledge, interested readers can read the HTML tutorial and CSS tutorial provided by this site.

The complete sample code is as follows:

<?php
    class Calendar{
        private $year, $month, $start_week, $days;
        /**
         * 构造方法，用来初始化一些日期属性
         */
        function __construct(){
            $this->year = isset($_GET[&#39;year&#39;])?$_GET[&#39;year&#39;]:date(&#39;Y&#39;);
            $this->month = isset($_GET[&#39;month&#39;])?$_GET[&#39;month&#39;]:date(&#39;m&#39;);
            $this->start_week = date(&#39;w&#39;, mktime(0, 0, 0, $this->month, 1, $this->year));
            $this->days = date(&#39;t&#39;, mktime(0, 0, 0, $this->month, 1, $this->year));
        }
        /**
         * 魔术方法，用来打印整个日历
         * @return string [日历的html代码]
         */
        function __toString(){
            $output = &#39;&#39;;
            $output = &#39;<table>&#39;;
            $output .= $this->changeDate();
            $output .= $this->weeksList();
            $output .= $this->daysList();
            $output .= &#39;</table>&#39;;
            return $output;
        }
        /**
         * 输出周列表
         * @return [string] [html 代码]
         */
        private function weeksList($output=&#39;&#39;){
            $week = array(&#39;日&#39;,&#39;一&#39;,&#39;二&#39;,&#39;三&#39;,&#39;四&#39;,&#39;五&#39;,&#39;六&#39;);
            $output .= &#39;<tr>&#39;;
            for ($i=0; $i < count($week); $i++) {
                $output .= &#39;<th>&#39;.$week[$i].&#39;</th>&#39;;
            }
            $output .= &#39;</tr>&#39;;
            return $output;
        }
        /**
         * 输出日期列表
         * @return [string]
         */
        private function daysList($output=&#39;&#39;){
            $output .= &#39;<tr>&#39;;
            for ($i=0; $i < $this->start_week; $i++) {
                $output .= &#39;<td> </td>&#39;;
            }
            for ($j=1; $j <= $this->days; $j++) {
                $i++;
                if($j == date(&#39;d&#39;) && $this->year == date(&#39;Y&#39;) && $this->month == date(&#39;m&#39;)){
                    $output .= &#39;<td>&#39;.$j.&#39;</td>&#39;;
                }else{
                    $output .= &#39;<td>&#39;.$j.&#39;</td>&#39;;
                }
                if($i%7 == 0) $output .= &#39;</tr><tr>&#39;;
            }
            while($i%7 !== 0){
                $output .= &#39;<td> </td>&#39;;
                $i++;
            }
            $output .= &#39;</tr>&#39;;
            return $output;
        }
        /**
         * 处理上一年的数据
         * @param  [type] $year  [年份]
         * @param  [type] $month [月份]
         * @return [type]        [description]
         */
        private function prevYear($year, $month){
            $year -= 1;
            if($year < 1970) $year = 1970;
            return "year=$year&month=$month";
        }
        /**
         * 处理上一月的数据
         * @param  [type] $year  [年份]
         * @param  [type] $month [月份]
         * @return [type]        [description]
         */
        private function prevMonth($year, $month){
            if($month == 1){
                $year -= 1;
                if($year < 1970) $year = 1970;
                $month = 12;
            }else{
                $month--;
            }
            return "year=$year&month=$month";
        }
        /**
         * 处理下一年的数据
         * @param  [type] $year  [年份]
         * @param  [type] $month [月份]
         * @return [type]        [description]
         */
        private function nextYear($year, $month){
            $year += 1;
            if($year > 2038) $year = 2038;
            return "year=$year&month=$month";
        }
        /**
         * 处理下一月的数据
         * @param  [type] $year  [年份]
         * @param  [type] $month [月份]
         * @return [type]        [description]
         */
        private function nextMonth($year, $month){
            if($month == 12){
                $year --;
                if($year > 2038) $year = 2038;
                $month = 1;
            }else{
                $month++;
            }
            return "year=$year&month=$month";
        }
        /**
         * 调整年份和月份
         * @param  string $output [html代码]
         * @param  string $url   
         * @return [type]        
         */
        private function changeDate($output=&#39;&#39;, $url=&#39;index.php&#39;){
            $output .= &#39;<tr>&#39;;
            $output .= &#39;<td><a href="&#39;.$url.&#39;?&#39;.$this->prevYear($this->year, $this->month).&#39;">&#39;.&#39;<<&#39;.&#39;</a></td>&#39;;
            $output .= &#39;<td><a href="&#39;.$url.&#39;?&#39;.$this->prevMonth($this->year, $this->month).&#39;">&#39;.&#39;<&#39;.&#39;</a></td>&#39;;
            $output .= &#39;<td colspan="3">&#39;;
            $output .= &#39;<form>&#39;;
            $output .= &#39;<select name="year" onchange="window.location=\&#39;&#39;.$url.&#39;?year=\&#39;+this.options[selectedIndex].value+\&#39;&month=&#39;.$this->month.&#39;\&#39;">&#39;;
            for ($i=1970; $i <=2038; $i++) {
                $selected = ($i == $this->year)?&#39;selected="selected"&#39;:&#39;&#39;;
                $output .= &#39;<option value="&#39;.$i.&#39;" &#39;.$selected.&#39;>&#39;.$i.&#39;</option>&#39;;
            }
            $output .= &#39;</select>&#39;;
            $output .= &#39;<select name="month" onchange="window.location=\&#39;&#39;.$url.&#39;?year=&#39;.$this->year.&#39;&month=\&#39;+this.options[selectedIndex].value">&#39;;
            for ($j=1; $j <=12; $j++) {
                $selected = ($j == $this->month)?&#39;selected="selected"&#39;:&#39;&#39;;
                $output .= &#39;<option value="&#39;.$j.&#39;" &#39;.$selected.&#39;>&#39;.$j.&#39;</option>&#39;;
            }
            $output .= &#39;</select>&#39;;
            $output .= &#39;</form>&#39;;
            $output .= &#39;</td>&#39;;
            $output .= &#39;<td><a href="&#39;.$url.&#39;?&#39;.$this->nextMonth($this->year, $this->month).&#39;">&#39;.&#39;>&#39;.&#39;</a></td>&#39;;
            $output .= &#39;<td><a href="&#39;.$url.&#39;?&#39;.$this->nextYear($this->year, $this->month).&#39;">&#39;.&#39;>>&#39;.&#39;</a></td>&#39;;
            $output .= &#39;</tr>&#39;;
            return $output;
        }
    }
?>
<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>PHP实现简单的日历程序</title>
    <style>
        table{
            border: 1px solid #ccc;
        }
        .fontb{
            color: white;
            background: blue;
        }
        th{
            width: 30px;
        }
        td,th{
            height:30px;
            text-align: center;
        }
        form{
            margin: 0px;
            padding: 0px;
        }
    </style>
</head>
<body>
    <?php
        $calendar = new Calendar;
        echo $calendar;
    ?>
</body>
</html>

The running results are as shown below:

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