数组 – 我可以定义不同类型的数组类型吗？

发布时间：2020-12-15 04:16:27 所属栏目：大数据来源：网络整理

导读：我想定义一个由不同类型组成的数组类型,例如String,Integer,Boolean,Double等,但没有对象,结构或任何这种性质.然后我想将此类型用作函数参数,例如…… type TMyArray = array of ...?...;function GetSomething(const Input: TMyArray): String;var X: Integ

我想定义一个由不同类型组成的数组类型,例如String,Integer,Boolean,Double等,但没有对象,结构或任何这种性质.然后我想将此类型用作函数参数,例如……

type
  TMyArray = array of ...?...;

function GetSomething(const Input: TMyArray): String;
var
  X: Integer;
begin
  for X:= 0 to Length(Input) - 1 do begin
    //Identify type and handle accordingly...
    //Serialize data for the result...

  end;
end;

并像…一样使用它

Variable:= GetSomething(['some string',123,'something else',12.3,false]);

那么,在迭代这样一个数组时,如何识别每个元素的类型？

我很确定这是可能的,但甚至不知道要搜索什么术语.我该怎么做呢？

我是否必须将其定义为Variants数组？或者有没有办法确定数组接受哪些类型？

编辑

不要改变任何问题,但在RRUZ的答案之后,我发现了an intriguing article关于性能的不同方式……

解决方法

如果你的Delphi版本支持RTTI,你可以使用 TValue的数组和Kind属性.

{$APPTYPE CONSOLE}


uses
  System.TypInfo,System.Rtti,System.SysUtils;


function GetSomething(const Input: array of TValue): String;
var
  X: Integer;
  LValue : TValue;
begin
  for LValue in Input  do begin
     case LValue.Kind of
       tkUnknown: Writeln('Unknown');
       tkInteger:  Writeln(Format('The Kind of the element is Integer and the value is %d',[LValue.AsInteger]));
       tkChar: Writeln('Char');
       tkEnumeration: if LValue.TypeInfo=TypeInfo(Boolean) then Writeln(Format('The Kind of the element is Boolean and the value is %s',[BoolToStr(LValue.AsBoolean,True)]));
       tkFloat: Writeln(Format('The Kind of the element is Float and the value is %n',[LValue.AsExtended]));
       tkString: Writeln('String');
       tkSet: Writeln('Set');
       tkClass: Writeln('Class');
       tkMethod:Writeln('method');
       tkWChar: Writeln('WChar');
       tkLString: Writeln('String');
       tkWString: Writeln('String');
       tkVariant: Writeln('Variant');
       tkArray: Writeln('Array');
       tkRecord: Writeln('Record');
       tkInterface: Writeln('Interface');
       tkInt64: Writeln('Int64');
       tkDynArray: Writeln('DynArray');
       tkUString:  Writeln(Format('The Kind of the element is String and the value is %s',[LValue.AsString]));
       tkClassRef:  Writeln('Class Ref');
       tkPointer: Writeln('Pointer');
       tkProcedure:  Writeln('procedure');
     end;
  end;
end;

begin
  try
    GetSomething(['some string',false]);
  except
    on E: Exception do
      Writeln(E.ClassName,': ',E.Message);
  end;
  Readln;
end.

另一种选择是使用const数组

{$APPTYPE CONSOLE}

uses
  SysUtils;


procedure GetSomething(const Input: array of const);
var
  LIndex: Integer;
begin
  for LIndex := Low(Input) to High(Input) do
  begin
    case Input[LIndex].VType of
      vtWideString: Writeln('WideString = ''',WideString(Input[LIndex].VWideChar),'''');
      vtInt64: Writeln('Int64 = ',Input[LIndex].VInt64^);
      vtCurrency: Writeln('Currency = ',CurrToStr(Input[LIndex].VCurrency^));
      vtInteger: Writeln('Integer = ',Input[LIndex].VInteger);
      vtBoolean: Writeln('Boolean = ',BoolToStr(Input[LIndex].VBoolean,True));
      vtChar: Writeln('Char = ''',Input[LIndex].VChar,'''');
      vtExtended: Writeln('Extended = ',FloatToStr(Input[LIndex].VExtended^));
      vtString: Writeln('ShortString = ''',Input[LIndex].VString^,'''');
      vtPChar: Writeln('PChar = ''',Input[LIndex].VPChar,'''');
      vtAnsiString: Writeln('AnsiString = ''',Ansistring(Input[LIndex].VAnsiString),'''');
      vtWideChar: Writeln('WideChar = ''',Input[LIndex].VWideChar,'''');
      vtPWideChar: Writeln('PWideChar = ''',Input[LIndex].VPWideChar,'''');
      vtUnicodeString : Writeln('UnicodeString = ''',string(Input[LIndex].VUnicodeString),'''');
    else
      Writeln('Unsupported');
    end;
  end;
end;

begin
  try
    GetSomething(['some string',E.Message);
  end;
  Readln;
end.

（编辑：李大同）

【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容!