最近搗鼓瞭通過調高德地圖行政區劃api來獲取城市信息的小demo，但做的項目有一個功能要求通過城市首字母區分城市的功能
類似於這樣：
首先我想的是通過PHP來解決
實現原理是獲取漢字的ASCII碼通過對比判斷然後返回漢字的首字母
獲取首字母代碼如下：
function getFirstCharter($str)
{
$str = mb_convert_encoding($str, 'gb2312','UTF-8');// 如果程序是gbk的，此行就要註釋掉
if (preg_match("/^[x7f-xff]/", $str)) {
$fchar = ord($str {
0});
if ($fchar >= ord("A") and $fchar <= ord("z")) return strtoupper($str {
0});
$a = $str;
$val = ord($a {
0}) * 256 + ord($a {
1}) - 65536;
if ($val >= -20319 and $val <= -20284) return "A";
if ($val >= -20283 and $val <= -19776) return "B";
if ($val >= -19775 and $val <= -19219) return "C";
if ($val >= -19218 and $val <= -18711) return "D";
if ($val >= -18710 and $val <= -18527) return "E";
if ($val >= -18526 and $val <= -18240) return "F";
if ($val >= -18239 and $val <= -17923) return "G";
if ($val >= -17922 and $val <= -17418) return "H";
if ($val >= -17417 and $val <= -16475) return "J";
if ($val >= -16474 and $val <= -16213) return "K";
if ($val >= -16212 and $val <= -15641) return "L";
if ($val >= -15640 and $val <= -15166) return "M";
if ($val >= -15165 and $val <= -14923) return "N";
if ($val >= -14922 and $val <= -14915) return "O";
if ($val >= -14914 and $val <= -14631) return "P";
if ($val >= -14630 and $val <= -14150) return "Q";
if ($val >= -14149 and $val <= -14091) return "R";
if ($val >= -14090 and $val <= -13319) return "S";
if ($val >= -13318 and $val <= -12839) return "T";
if ($val >= -12838 and $val <= -12557) return "W";
if ($val >= -12556 and $val <= -11848) return "X";
if ($val >= -11847 and $val <= -11056) return "Y";
if ($val >= -11055 and $val <= -10247) return "Z";
} else {
return false;
}
}