将阿拉伯数字转换为中文书面数字

前几天有人在群里写这个，好像挺纠结的样子，就顺手帮他写了一个。

主要思路是中文的数字读法是四位四位分的，高位数字的读法就是xxxx亿xxxx万xxxx。

void Start () {
//测试数据
Debug.Log (full_toword(987654321));
Debug.Log (full_toword(907654321));
Debug.Log (full_toword(9000900654321));
Debug.Log (full_toword(9000900000000));
}


string full_toword(long i){
long[] a=new long[4];//按照万亿兆拆分输入数字
a [0] = i/1000000000000;
a [1] = i / 100000000 % 10000;
a [2] = i / 10000 % 10000;
a [3] = i % 10000;
string[] s = new string[4];//每4位数字对应的字符串
s [0] = thousand_toword ((int)a [0],"兆");
s [1] = thousand_toword ((int)a [1],"亿");
s [2] = thousand_toword ((int)a [2],"万");
s [3] = thousand_toword ((int)a [3],"");
for (int j = 0; j < 4; j++) {
if (0 == a [j])
s [j] = "";//除去高位零
else
break;
}
for (int j = 3; j >= 0; j--) {
if (0 == a [j])
s [j] = "";//除去低位零
else
break;
}
int max;//获取数字中最大的单位
for (max = 0; max < 4; max++) {
if (a [max] != 0)
break;
}
for (int j = max + 1; j < 4; j++) {
if ((0 != a [j]) && (a [j] / 1000 == 0))
s [j] = "零" + s [j];//如果该四位数字不是零，并且不是最高位，那么在前面加一个零
}
string _out = s[0]+s[1]+s[2]+s[3];
return _out;
}

///输出四位数字的读法
string thousand_toword(int i,string ss){
int[] a=new int[4];
a [0] = i / 1000;
a [1] = i / 100 % 10;
a [2] = i / 10 % 10;
a [3] = i % 10;
string[] s = new string[4];
s [0] = toword (a [0],"千");
s [1] = toword (a [1],"百");
s [2] = toword (a [2],"十");
s [3] = toword (a [3],"");
for (int j = 0; j < 4; j++) {
if (0 == a [j])
s [j] = "";//除去高位零
else
break;
}
for (int j = 3; j >= 0; j--) {
if (0 == a [j])
s [j] = "";//除去低位零
else
break;
}
for (int j = 0; j < 3; j++) {
if (("零" == s [j]) && ("零" == s [j+1]))
s [j] = "";//将连续的零合并为一个，比如1001这样的数字
}
string _out = s[0]+s[1]+s[2]+s[3]+ss;
return _out;
}

//将对应的一位阿拉伯数字转换为汉字
string toword(int i,string s){
switch (i) {
case 0:
return("零");
case 1:
return("一"+s);
case 2:
return("二"+s);
case 3:
return("三"+s);
case 4:
return("四"+s);
case 5:
return("五"+s);
case 6:
return("六"+s);
case 7:
return("七"+s);
case 8:
return("八"+s);
case 9:
return("九"+s);
default: 
return("");

}
}
}

附一张输出结果，没问题