php获取各城市72小时天气预报[中国天气网]

function getweather($city,$data='data.txt')//获取天气预报内容
{
    $urlarr=unserialize(file_get_contents($data));
    if($urlarr[$city])
    {
        $url = $urlarr[$city];$text=$city;
        $lines_string = file_get_contents($url);
        $lines_string = explode("<!--day",$lines_string);
        if(!$lines_string[1]){return "无法获取到该城市的天气信息!";exit;}
        $lines_string_3=explode("未来",$lines_string[3]);
        $lines_array =array(str_replace('1-->','',$lines_string[1]),str_replace('2-->','',$lines_string[2]),str_replace('3-->','',$lines_string_3[0]));
        for($i=0;$i< count($lines_array); $i ++)
        {
            $tiqian=array("℃","高温","低温");$tihou=array("度","","");$nowarray=str_replace($tiqian,$tihou,strip_tags($lines_array[$i]));
            $datearray=explode("日",$nowarray);$wtext[$i]=trim($datearray[0])."日";//获取日期
            $weather=explode("白天",$nowarray);$weather=explode("夜间",$weather[1]);
            $baiarr=wchangearray(explode("r",$weather[0]));//白天天气
            $yearr=wchangearray(explode("r",$weather[1]));//夜间天气
            if($baiarr[0]==$yearr[0]){$wtext[$i].=$baiarr[0];}else{$wtext[$i].=$baiarr[0]."转".$yearr[0];}//将天气添加到返回值里
            $wtext[$i].=$baiarr[1]."到".$yearr[1];//将气温添加到返回值里
            if($baiarr[2]==$yearr[2]){$wtext[$i].=$baiarr[2];}else{$wtext[$i].=str_replace("风","",$baiarr[2]."转".$yearr[2]);$wtext[$i].="风";}//将风向添加到返回值里
            if($baiarr[3]!="微风"){$wtext[$i].=$baiarr[3];}//将风力添加到返回值
        }
        return $text.implode("",$wtext);
    }else{
        return "无法获取到该城市的天气信息!";
    }
}

function wchangearray($arr)//对数组进行键值排序
{
	foreach($arr as $v)
	{if(!trim($v))continue;
	$value[]=trim($v);}return $value;
}