在delphi中判断字符串是否数字，以及精度处理函数

// 判断是否是数值型   By yangxiao  2007.7.21
function isNumeric(strText: WideString): Boolean;
var
  s: string;
  i, l, p: Integer;
begin
  Result := False;
  l := Length(strText);
  if l = 0 then Exit;
  s := '';
  for i:=1 to l do
  begin
    case strText[i] of
      '0'..'9':
        s := s + strText[i];
      'E', 'e', '+', '-', '.':
      begin
        p := PosEx(strText[i], strText, i+1);
        if p = 0 then
        begin
          case strText[i] of
            'E', 'e':
              if (i=1) or (i=l) then Exit;
            '+', '-':
              if i > 1 then
                case strText[i-1] of
                  'E', 'e':
                    s := s + strText[i];
                else
                  Exit;
                end;
          end;
        end
        else