类对象初始化 [英] class object initialisation
问题描述
我一直被教导使用inialization列表来初始化数据
班级成员。我意识到初始化基元和指针使用
一个inialization列表与一个赋值完全相同，但对于类
类型它有不同的效果 - 它调用复制构造函数。
我的问题是什么时候不使用初始化列表初始化数据
班级成员？
问候
Adi
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Hi,
I have always been taught to use an inialization list for initialising data
members of a class. I realize that initialsizing primitives and pointers use
an inialization list is exactly the same as an assignment, but for class
types it has a different effect - it calls the copy constructor.
My question is when to not use an initalisation list for initialising data
members of a class?
Regards
Adi
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推荐答案
" A" < A@iprimus.com.au>在留言中写道
新闻：3f ******** @ news.iprimus.com.au ...
|我一直被教导使用一个初始化列表进行初始化
数据
|班级成员。我意识到初始化原语和指针
使用
| inialization列表与赋值完全相同，但对于类
|类型它有不同的效果 - 它调用复制构造函数。
|
|我的问题是何时不使用初始化列表来初始化数据
|班级成员？
只有当你无法做到时，例如当一个涉及
的复杂计算需要几个中间变量而且一个专用函数不需要b $ b bb是有意义的。
IMO初始化列表应始终是首选。
问候，
-
http://ivan.vecerina.com
"A" <A@iprimus.com.au> wrote in message
news:3f********@news.iprimus.com.au...
| I have always been taught to use an inialization list for initialising
data
| members of a class. I realize that initialsizing primitives and pointers
use
| an inialization list is exactly the same as an assignment, but for class
| types it has a different effect - it calls the copy constructor.
|
| My question is when to not use an initalisation list for initialising data
| members of a class?
Only when you are unable to, e.g. when a complex computation involving
several intermediate variables is needed and a dedicated function doesn''t
make sense.
IMO the initialization list should always be preferred.
Regards,
--
http://ivan.vecerina.com
" A" < A@iprimus.com.au>在消息中写道
新闻：3f ******** @ news.iprimus.com.au ...
"A" <A@iprimus.com.au> wrote in message
news:3f********@news.iprimus.com.au...
我一直被教导使用inialization列表来初始化一个类的
数据成员。我意识到初始化基元和指针
使用一个inialization列表与一个赋值完全相同，但对于类
类型它有不同的效果 - 它调用复制构造函数。
我的问题是什么时候不使用初始化列表初始化数据
一个类的成员？
Hi,
I have always been taught to use an inialization list for initialising data members of a class. I realize that initialsizing primitives and pointers use an inialization list is exactly the same as an assignment, but for class
types it has a different effect - it calls the copy constructor.
My question is when to not use an initalisation list for initialising data
members of a class?
基本的经验法则是任何可以去的东西在初始化列表中
应该去那里。显然，你不能把这样的东西放在那里：
if（a）
i = 2;
else
i = 4;
The basic rule of thumb is that anything that can go in the initialize list
should go there. Obviously, you can''t put something like this in there:
if (a)
i = 2;
else
i = 4;
> >
我一直被教导使用一个inialization列表来初始化数据
I have always been taught to use an inialization list for initialising data
一个类的成员。我意识到初始化基元和指针
members of a class. I realize that initialsizing primitives and pointers
使用
一个inialization列表与一个赋值完全相同，但对于类
类型它有不同的效果 - 它调用复制构造函数。
我的问题是什么时候不使用初始化列表初始化一个类的
数据成员？
an inialization list is exactly the same as an assignment, but for class
types it has a different effect - it calls the copy constructor.
My question is when to not use an initalisation list for initialising data members of a class?
基本规则拇指是任何可以进入初始化
The basic rule of thumb is that anything that can go in the initialize
列表的东西都应该去那里。显然，你不能把这样的东西放在那里：
如果（a）
我= 2;
其他
我= 4;
list should go there. Obviously, you can''t put something like this in there:
if (a)
i = 2;
else
i = 4;
很多（如果不是大多数）这些案例都可以被？：运算符覆盖：
MyClass（int a）：i（a？2：4）{ }
/ Erik
Many, if not most, of those cases can be covered by the ?: operator:
MyClass(int a) : i(a ? 2 : 4) {}
/ Erik
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