How to convert full-width characters to half-width characters

As we know, in Windows, both Chinese and full-width characters account for two bytes and use the ASCII chart 2 (codes 128–255). We can, by this point, detect whether the user entered Chinese and full-width characters. In fact, the first byte of the full-width character is always set to 163, while the second byte is the same half-width character code plus 128 (excluding spaces). If the half angle A is 65, then full-width A is 163 (first byte), 193 (second byte, 128+65). And for Chinese, its first byte is set to be greater than 163, (such as ' A ' is: 176 162), we can detect Chinese without conversion.

The above is only for my personal test results, and I am learning to program less than half a month. If there are errors or leaks, please do not hesitate to enlighten us. Let me give you a routine for your reference.

Create a new form and place Button1, Edit1, and edit2 on the form.

/* Enter full-width characters, Chinese, half-width characters, or promiscuous input in the edit1. Click the text in Button1,edit1 to display in Edit2 and convert all full-width characters. Note that the program does not respond correctly to the special character Furu 255 (press ALT and press the keypad 2, 5, 5 input). */

void __fastcall tform1::button1click(tobject *sender)
{
　int nlength=edit1->text.length();
　if (nlength==0)
　　return;
　ansistring str="";
　char *ctmp=new char[nlength+1];
　strpcopy(ctmp,edit1->text);
　byte c1,c2;
　int i;
　for (i=0;i<nlength;i++)
　{
　　c1=ctmp[i];
　　c2=ctmp[i+1];
　　if (c1==163)//判断是否为全角字符
　　{
　　　str=str+ansistring((char)(c2-128));
　　　i++;
　　　continue;
　　}
　　if (c1>163)//判断是否为文字
　　{
　　　str=str+ansistring((char)c1);
　　　str=str+ansistring((char)c2);
　　　i++;
　　　continue;
　　}
　　if ((c1==161) && (c2==161))//全角空格是个特例，另加处理
　　　{
　　　　str=str+" ";
　　　　i++;
　　　　continue;
　　　}
　　str=str+ ansistring(char(c1));
　}
　edit2->text=str;
　delete ctmp;ctmp=null;
}

The above code is compiled by C++builder5.0/win98 SE.