original code: function TForm1.fromstr(const cstring: string; const nlen: integer): string; begin if length(cstring) >= nlen then result:= copy(cstring,nlen,succ(length(cstring)-nlen)) else result:='' ; end; function TForm1.Parse(var s: string; const c: string): string; { Parse a string on a given delimitor destructively (s=Right Hand Side(RHS)), returning Left Hand Side(LHS) } var p: Integer; begin p := ansiPos(c,s); if p > 0 then begin Result := Copy(s,1,p-1);{ Left hand side } s := FromStr(s,p Length(c));{ Right hand side } end else begin Result := s; s := ''; end; end; I try to apply parse function: procedure TForm1.Button6Click(Sender: TObject); var i,j :string; begin i:=edit3.text ;{here type c in edit3} j:=edit4.text; {abcedfg in edit4} parse(i,j); showmessage(parse(i,j)); end; The result should return to 'ab' in LHS, 'defg' in RHS. but it returns '' in the showmessage dialog! Q1: why it return ''? Q2: how many results does parse function return? 1 or 2 and which (s or result)? Q3: what are the differences between pos function and antipos function? please show me example if possible. Hope somebody can help me out! thx!

lhh您好：

1、看了下程式，我想应该在edit3处输入abcedfg，在edit4输入c才能正确的得出您所要的结果。原因：在i:=c,j:=abcedfg;看那句p := ansiPos(c,s);时，如果按原来的输入方式代入p:=ansipos(j,i)-->p:=ansipos(abcedfg,c)，所以p始终返回0，也就只有返回您所看到的为空的结果；
2、如果按照您的上述代码，做了第一步的调整（edit3处输入abcedfg，在edit4输入c）之后得出的结果应该是"edfg"只返回定位字符的右边字符，因为代码中返回结果是showmessage(parse(i,j));parse(i,j)只返回一个值,也即fromstr function 的result，但如果您想返回定位字符的左右两边的值，可以改成这样子：
function TForm1.Parse(var s: string; const c: string): string;
var
  p: Integer;
begin
  p := ansiPos(c,s);
  if p > 0 then
    begin
      Result := Copy(s,1,p-1);{ Left hand side }
      showmessage(result);//新增一句,用于返回Parse函数的值
      s := FromStr(s,p Length(c));{ Right hand side }
    end
  else
    begin
      Result := s;
      s := '';
    end;
end;
可以试试看
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thanx so much !deity