foreach追加有关问题，求高手帮忙看看

foreach 追加问题，求高手帮忙看看。

$citycode = array(
"北京"=>"101010100",
"朝阳"=>"101010300"
);

foreach ($citycode as $arr => $value) {
$citycode[$arr] = "http://weather.xxx.com/".substr($citycode[$arr], 3,4).".txt";
//$citycode[$arr] .= "http://weather.xxx.com/".$citycode[$arr].".txt";
}

/*
功能：按行保存为文件
*/

saveFile('api/weather.txt',implode("\r\n",$citycode));


?>


我想根据数组保存为换行文件，如下：
http://weather.xxx.com/0101.txt
http://weather.xxx.com/101010100.txt
http://weather.xxx.com/0103.txt
http://weather.xxx.com/101010300.txt

要怎么做？
我现在只能做到：
http://weather.xxx.com/0101.txt
http://weather.xxx.com/0103.txt

怎么追加进去呢？
------解决思路----------------------

foreach ($citycode as $arr => $value) {
$citycode[$arr] = "http://weather.xxx.com/".substr($citycode[$arr], 3,4).".txt";
//$citycode[$arr] .= "http://weather.xxx.com/".$citycode[$arr].".txt";
}

你这样明显的用t同样的键值覆盖了之前的值嘛，要不就换个键值如

$citycode[$arr.'1'] = "http://weather.xxx.com/".substr($citycode[$arr], 3,4).".txt";

------解决思路----------------------

$citycode = array(
	"北京"=>"101010100",
	"朝阳"=>"101010300"
);

$tmp = array();

foreach ($citycode as $arr => $value) {
	$tmp[] = "http://weather.xxx.com/".substr($value, 3,4).".txt";
	$tmp[] = "http://weather.xxx.com/".$value.".txt";
}

echo implode("\r\n", $tmp);

//saveFile('api/weather.txt',implode("\r\n",$citycode));

http://weather.xxx.com/0101.txt
http://weather.xxx.com/101010100.txt
http://weather.xxx.com/0103.txt
http://weather.xxx.com/101010300.txt

楼主是想这样么？
------解决思路----------------------
$citycode[$arr] .= "http://weather.xxx.com/".$citycode[$arr].".txt";
这里的$citycode[$arr] 已经被修改了
被上一句$citycode[$arr] = "http://weather.xxx.com/".substr($citycode[$arr], 3,4).".txt";

另外：$citycode[$arr] .= "http://weather.xxx.com/".$citycode[$arr].".txt";
使用拼接的话你忘记换行了。

改这样就可以了

$citycode = array(
"北京"=>"101010100",
"朝阳"=>"101010300"
);

$result = array();

foreach ($citycode as $arr => $value) {
    array_push($result,"http://weather.xxx.com/".substr($value, 3,4).".txt");
    array_push($result,"http://weather.xxx.com/".$value.".txt");
}

/*
 功能：按行保存为文件
*/

saveFile('api/weather.txt',implode("\r\n",$result));

http://weather.xxx.com/0101.txt
http://weather.xxx.com/101010100.txt
http://weather.xxx.com/0103.txt
http://weather.xxx.com/101010300.txt