Lazarus 中的字符串 String,AnsiString,UnicodeString,UTF8String,WideString

  Lazarus 在字符串处理上默认是UTF8编码

UTF8String          = type ansistring;

  如下面这段代码

s:=trim('abcd123');
  lbStrLen1.Caption:=IntToStr(Length(s));   {本身就是UTF8编码}
  lbStrLen2.Caption:=IntToStr(length(Utf8ToAnsi(s)));
  lbStrLen3.Caption:=IntToStr(Length(UTF8Decode(s)));

  将输出 7 ，7 ，7

还是那段代码

s:=trim('附件123');
  lbStrLen1.Caption:=IntToStr(Length(s));   {本身就是UTF8编码}
  lbStrLen2.Caption:=IntToStr(length(Utf8ToAnsi(s)));
  lbStrLen3.Caption:=IntToStr(Length(UTF8Decode(s)));

  结果是 9，7，5

UTF8Decode(s) 解码是 UnicodeString。

话说到这里那可不可以用强制呢！说不定编译器很智能。

s:='复件123';
  Memo3.Append(format('with %20s to %20s  :  len=%d',['AnsiString(s)',s,length(s)]));
  Memo3.Append(format('with %20s to %20s  :  len=%d',['UnicodeString(s)',UnicodeString(s),length(UnicodeString(s))]));
  Memo3.Append(format('with %20s to %20s  :  len=%d',['WideString(s)',WideString(s),length(WideString(s))]));
  Memo3.Append(format('with %20s to %20s  :  len=%d',['UTF8String(s)',UTF8String(s),length(UTF8String(s))]));
  Memo3.Append(format('with %20s to %20s  :  len=%d',['UTF8Decode(s)',UTF8Decode(s),length(UTF8Decode(s))]));
  Memo3.Append(format('with %20s to %20s  :  len=%d',['Utf8ToAnsi(s)',Utf8ToAnsi(s),length(Utf8ToAnsi(s))]));

结果是

with        AnsiString(s) to            复件123  :  len=9
with     UnicodeString(s) to            复件123  :  len=6
with        WideString(s) to            复件123  :  len=6
with        UTF8String(s) to            复件123  :  len=9
with        UTF8Decode(s) to              ??123  :  len=5
with        Utf8ToAnsi(s) to              ??123  :  len=7

强制后长度等于6 ，不明白啊！