delphi类继承的疑惑 ( 积分: 50 )

D

dysysu

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GUEST, unregistred user!

• 2007-08-22

• #1

TApple是TFruid的子类
TFruid有一个属性id
TApple有一个属性name


function produceID(var fruid:TFruid);
begin
fruid.id:='12345678';
end;

apple:TApple;
fruid:TFruid;
apple:=TApple.Create;
fruid:=apple as TFruid;

produceID(fruid);

apple.name:='This is an apple';

showMessage(intTOstr(apple.id));
showMessage(apple.name);

这样结果不正确

 

D

dysysu

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GUEST, unregistred user!

• 2007-08-22

• #2

问题已解决

 

B

Buddy.Sun

Unregistered / Unconfirmed

GUEST, unregistred user!

• 2007-08-22

• #3

那我来接分

 

L

linuxping

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GUEST, unregistred user!

• 2007-08-23

• #4

fruid:=apple as TFruid
浪费

intTOstr(apple.id))
????

接分

 

D

dysysu

Unregistered / Unconfirmed

GUEST, unregistred user!

• 2007-08-24

• #5

fruid:=apple as TFruid
浪费
为什么浪费?


分配好分数后要怎么给分?

 

T

tianxin7131

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GUEST, unregistred user!

• 2007-08-24

• #6

呵呵 ，和我一样，前天刚发完贴，马上想到错误的出处，再调试果然OK
以后得注意啦，多想想再发贴哦。

 

L

linuxping

Unregistered / Unconfirmed

GUEST, unregistred user!

• 2007-08-30

• #7

fruid是apple 的基类,根本不用强制转换....
只有从父类向子类转换时才用强制转换
l:Tlist;
e:Tedit;

e:=Tedit.create;
l:=Tlist.create;

l.items.add(e);

e:=l.items[0] as TEdit
//l.items[0] 为Tobject类型.从父类向子类转换.

 

D

dysysu

Unregistered / Unconfirmed

GUEST, unregistred user!

• 2007-09-05

• #8

thx

 

D

dysysu

Unregistered / Unconfirmed

GUEST, unregistred user!

• 2007-09-05

• #9

多人接受答案了。