记录录入（无法初始化） [英] Record in record (Cannot initialize)

问题描述

我有2条记录如下：

TYPE
 TRecord2= packed record
  i2: Integer;
 end;

 TRecord1= packed record
  i1: Integer;
  R2: TRecord2;
 end;

。

我想初始化将字段记录到零，但是我不想使用FillMemory，所以我声明了2个常量记录，其中我初始化了这些字段。

I want to initialize the record fields to zero but I don't want to use FillMemory so I declared 2 constant records in which I initialize the fields.

CONST
  Record2c: TRecord2=
  (
   i2: 0;
  );

  Record1c: TRecord1=
  (
    i1: 0;
    R2: Record2c;      <------- error line
  );

但是，我不能将Record2c分配给R2字段。编译器说：E2029'（'expected but identifier'Record2c'found。

However, I cannot assign a Record2c to R2 field. The compiler says: E2029 '(' expected but identifier 'Record2c' found.

但是这样做（如果我在评论行错误的地方）：

But this works (if I comment the line where I have the error):

procedure test;
var Record1: TRecord1;
begin
 Record1:= Record1c;      // initialize variable by associating the constant to it
end

那么，我如何初始化R2字段

So, how do i initialize the R2 field?

推荐答案

只能使用真实常量初始化const ，真实的常量没有类型 - 是键入的常量。请参阅 已声明的常量 在Delphi文档中。你的代码中的 Record2c 是一个类型的常量，所以它不能在const表达式中使用，像初始化 Record1c 。你只需要在线定义 Record1c.R2 ：

You can only initialize consts with true constants. True constants do not have types — those are typed constants. See Declared Constants in the Delphi documentation. Record2c in your code is a typed constant, so it cannot be used in const expressions like the one required for initializing Record1c. You'll just have to in-line the definition of Record1c.R2:

const
  Record1c: TRecord1 = (
    i1: 0;
    R2: (i2: 0;);
  );

当您注释掉错误行时，您将离开 R2 字段默认初始化为零。

When you comment out the error line, you're leaving the R2 field default-initialized to zeros.

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