如何迭代与Delphi 6初始化的枚举类型，并避免“越界”错误？ [英] How to iterate initialized enumerated types with Delphi 6 and avoid the "out of bounds" error?

问题描述

我正在使用Delphi 6 Professional。我正在与一个声明enumberated类型的DLL libraty接口，如下所示：

$ p $ $ $ $ $ $ TExtDllEnum =（ENUM1 = $ 0，ENUM2 = $ 1， ENUM3 = $ 2，ENUM4 = $ 4，ENUM5 = $ 8，ENUM6 = $ 10）;

正如您所看到的，初始化的值不是连续的。如果我尝试使用for循环迭代类型，如下所示：

  var 
 e：TExtDllEnum; 
开始
为e：=低（TExtToDllEnum）为高（TExtToDllEnum）做
 ... //更多代码
结束; 
  

每个循环调用，Delphi依然递增e，从而为e创建不是成员的数值枚举类型（例如3），并导致越界错误。我怎样才能迭代枚举类型的for循环，只生成枚举类型的有效值？

谢谢。

  type $ b $ 
 b TExtDllEnum =（ENUM1 = $ 0，ENUM2 = $ 1，ENUM3 = $ 2，ENUM4 = $ 4，ENUM5 = $ 8，ENUM6 = $ 10）; 
 
 const 
 CExtDllEnumSet = [ENUM1，ENUM2，ENUM3，ENUM4，ENUM5，ENUM6]; 
 
 
 var 
 e：TExtDllEnum; 
 begin 
 e：= Low（TExtDllEnum）; 
而e <= High（TExtDllEnum）do 
 begin 
如果e在CExtDllEnumSet中，则
 WriteLn（Ord（e））; 
 
 Inc（e）; 
 end; 
 
 ReadLn; 
结束。 
  

---

并作为迭代器实现 - 只是为了好玩。
$ b $ $ $ $

$ b $ TExtDllEnum =（ENUM1 = $ 0，ENUM2 = $ 1，ENUM3 = $ 2，ENUM4 = $ 4， ENUM5 = $ 8，ENUM6 = $ 10）;
const
CExtDllEnumSet = [ENUM1，ENUM2，ENUM3，ENUM4，ENUM5，ENUM6];

类型
TMyIterator =类别
私人
FValue：TExtDllEnum;
public
构造函数Create;
函数Next：TExtDllEnum;
函数HasNext：Boolean;
end;

构造函数TMyIterator.Create;
begin
FValue：= Low（TExtDllEnum）;
end;

函数TMyIterator.HasNext：Boolean;
begin
结果：= FValue <=高（TExtDllEnum）;
end;

函数TMyIterator.Next：TExtDllEnum;
begin
结果：= FValue;

重复
Inc（FValue）;
直到（CExtDllEnumSet中的FValue）或（FValue> High（TExtDllEnum））
end;

var
MyIterator：TMyIterator;
begin
MyIterator：= TMyIterator.Create;

而MyIterator.HasNext做
WriteLn（Ord（MyIterator.Next））;

MyIterator.Free;

ReadLn;
结束。

I am using Delphi 6 Professional. I am interfacing with a DLL libraty that declares an enumberated type as follows:

TExtDllEnum = (ENUM1 = $0, ENUM2 = $1, ENUM3 = $2, ENUM4 = $4, ENUM5 = $8, ENUM6 = $10);

As you can see the initialized values are not contiguous. If I try to iterate the type using a for loop as follows:

var
    e: TExtDllEnum;
begin
    for e := Low(TExtToDllEnum) to High(TExtToDllEnum) do
    ... // More code
end;

Delphi still increments e by 1 each loop invocation and thereby creates numeric values for e that are not members of the enumerated type (for example, '3'), and resulting in an 'out of bounds' error. How can I iterate the enumerated type in a for loop that generates only valid values for the enumerated type?

Thanks.

解决方案

By defining a set of constants...

type
  TExtDllEnum = (ENUM1 = $0, ENUM2 = $1, ENUM3 = $2, ENUM4 = $4, ENUM5 = $8, ENUM6 = $10);

const
  CExtDllEnumSet = [ENUM1, ENUM2, ENUM3, ENUM4, ENUM5, ENUM6];


var
  e: TExtDllEnum;
begin
  e := Low(TExtDllEnum);
  while e <= High(TExtDllEnum) do
  begin
    if e in CExtDllEnumSet then 
      WriteLn(Ord(e));

    Inc(e);
  end;

  ReadLn;
end.

---

and implemented as an iterator - just for fun...

type
  TExtDllEnum = (ENUM1 = $0, ENUM2 = $1, ENUM3 = $2, ENUM4 = $4, ENUM5 = $8, ENUM6 = $10);
const
  CExtDllEnumSet = [ENUM1, ENUM2, ENUM3, ENUM4, ENUM5, ENUM6];

type
  TMyIterator = class
  private
    FValue: TExtDllEnum;
  public
    constructor Create;
    function Next: TExtDllEnum;
    function HasNext: Boolean;
  end;

  constructor TMyIterator.Create;
  begin
    FValue := Low(TExtDllEnum);
  end;

  function TMyIterator.HasNext: Boolean;
  begin
    Result := FValue <= High(TExtDllEnum);
  end;

  function TMyIterator.Next: TExtDllEnum;
  begin
    Result := FValue;

    repeat
      Inc(FValue);
    until (FValue in CExtDllEnumSet) or (FValue > High(TExtDllEnum))
  end;

var
  MyIterator: TMyIterator;
begin
  MyIterator := TMyIterator.Create;

  while MyIterator.HasNext do
    WriteLn(Ord(MyIterator.Next));

  MyIterator.Free;

  ReadLn;
end.

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