PHP练手：日历（代码简单，扩展容易）

<?php
    class Calendar{
        public $weekarray = array(&#39;星期日&#39;,&#39;星期一&#39;,&#39;星期二&#39;,&#39;星期三&#39;,&#39;星期四&#39;,&#39;星期五&#39;,&#39;星期六&#39;);
        public $firstDay = &#39;&#39;;//当月第一天
        public $firstNum = &#39;&#39;;//返回当月第一天对应的星期数字
        public $firstDayNum = &#39;&#39;;//当月第一天对应的中文星期
        
        /**
        *   指定日是星期几
        *   eg:$date=&#39;2014-07-21&#39;
        */
        public function getWeek($date){
            $date = strtotime($date);//strtotime() 函数将任何英文文本的日期时间描述解析为 Unix 时间戳
            $num = date(&#39;w&#39;,$date);//数字型的星期几，如: "0" (星期日) 至 "6" (星期六)
            return $num;
        }

        /**
        *   取得指定月有多少天
        *   eg:$month = &#39;2014-07&#39;
        */
        public function getMonthNum($month){
            $month = strtotime($month);
            return date(&#39;t&#39;,$month);//指定月份的天数
        }
        
        /**
        *   显示日历
        */
        public function show(){
            //取得当前日期
            $year = date(&#39;Y&#39;);
            $month = date(&#39;m&#39;);
            $day = date(&#39;d&#39;);
            echo &#39;<table border="1" style="text-align:center;">&#39;;
            echo &#39;<tr><td colspan="7">&#39;.$year.&#39;-&#39;.$month.&#39;</td></tr>&#39;;
            echo &#39;<tr><th>星期日</th><th>星期一</th><th>星期二</th><th>星期三</th><th>星期四</th><th>星期五</th><th>星期六</th></tr>&#39;;
            //取得当前月有多少天
            $yearMonth = &#39;$year."-".$month&#39;;
            $monthNum = $this->getMonthNum($yearMonth);
            //取得当前月第一天是星期几
            $this->firstDay = $year."-".$month."-01";
            $this->firstNum = $this->getWeek($this->firstDay);
            $this->firstDayNum = $this->weekarray[$this->firstNum];
            
            echo &#39;<tr>&#39;;
                for($i=1;$i<=$monthNum+($this->firstNum);$i++){
                    echo &#39;<td>&#39;;
                    if($i >= $this->firstNum+1){
                        $a = $i-$this->firstNum;
                        if($a == $day){
                            echo &#39;<p style="background-color:blue;color:#fff;">&#39;.$a.&#39;</p>&#39;;
                        }else{
                            echo &#39;<p>&#39;.$a.&#39;</p>&#39;;
                        }
                    }
                    echo &#39;</td>&#39;;
                    if($i%7 == 0){//每输出7列就换一行
                        echo &#39;</tr>&#39;;
                    }
                }
            echo &#39;</table>&#39;;
        }

    }
    
    $calendar = new Calendar();
    $calendar->show();