最近项目有个需求，在一个中英文（包括阿拉伯数字0-9）的海量词库中，提取每一个词语的首字母：
gannicus——>G
自由自在——>Z
2B——>E
傻X——>S
private function getfirstchar($s0){
$s=iconv('UTF-8','gb2312', $s0);
if (ord($s0)>128) { //汉字开头
$asc=ord($s{0})*256+ord($s{1})-65536;
if($asc>=-20319 and $asc<=-20284)return "A";
if($asc>=-20283 and $asc<=-19776)return "B";
if($asc>=-19775 and $asc<=-19219)return "C";
if($asc>=-19218 and $asc<=-18711)return "D";
if($asc>=-18710 and $asc<=-18527)return "E";
if($asc>=-18526 and $asc<=-18240)return "F";
if($asc>=-18239 and $asc<=-17923)return "G";
if($asc>=-17922 and $asc<=-17418)return "I";
if($asc>=-17417 and $asc<=-16475)return "J";
if($asc>=-16474 and $asc<=-16213)return "K";
if($asc>=-16212 and $asc<=-15641)return "L";
if($asc>=-15640 and $asc<=-15166)return "M";
if($asc>=-15165 and $asc<=-14923)return "N";
if($asc>=-14922 and $asc<=-14915)return "O";
if($asc>=-14914 and $asc<=-14631)return "P";
if($asc>=-14630 and $asc<=-14150)return "Q";
if($asc>=-14149 and $asc<=-14091)return "R";
if($asc>=-14090 and $asc<=-13319)return "S";
if($asc>=-13318 and $asc<=-12839)return "T";
if($asc>=-12838 and $asc<=-12557)return "W";
if($asc>=-12556 and $asc<=-11848)return "X";
if($asc>=-11847 and $asc<=-11056)return "Y";
if($asc>=-11055 and $asc<=-10247)return "Z";
}else if(ord($s)>=48 and ord($s)<=57){ //数字开头
switch(iconv_substr($s,0,1,'utf-8'))
{
case 1:return "Y";
case 2:return "E";
case 3:return "S";
case 4:return "S";
case 5:return "W";
case 6:return "L";
case 7:return "Q";
case 8:return "B";
case 9:return "J";
case 0:return "L";
}
}else if(ord($s)>=65 and ord($s)<=90){ //大写英文开头
return substr($s,0,1);
}else if(ord($s)>=97 and ord($s)<=122){ //小写英文开头
return strtoupper(substr($s,0,1));
}
else
{
return iconv_substr($s0,0,1,'utf-8');//中英混合的词语，不适合上面的各种情况，因此直接提取首个字符即可
}
}
遗留问题：仍有少量词语无法提取，如亘古不灭，的G 没有提取出来
最终效果如图：
