什么时候应该使用“新”? [英] When should use "new"?
问题描述
对于一个类,MyClass,有两种实例化对象的方法:
1. MyClass * MC = new MyClass();
2. MyClass MC;
一般来说,什么时候应该使用1和2?什么是
使用它们的优点/缺点?
谢谢!
" garyolsen" < GA ******* @ yahoo.com>在留言新闻中写道:l6 ********************** @ bgtnsc05-news.ops.worldnet.att.net ...对于一个类,MyClass,有两种实例化对象的方法:
1. MyClass * MC = new MyClass();
2. MyClass MC;
一般来说,什么时候应该使用1和2?什么是使用其中的优点/缺点?
当#2不够时使用#1。
" garyolsen" < GA ******* @ yahoo.com>在留言中写道
新闻:l6 ********************** @ bgtnsc05-news.ops.worldnet.att.net .. 。对于一个类MyClass,有两种实例化对象的方法:
1. MyClass * MC = new MyClass();
> 2. MyClass MC;
一般来说,什么时候应该使用1和2?
一般情况下,使用第二种形式,必要时使用第一种形式。
什么是使用其中的优点/缺点?
我能想到的第二种形式
的唯一缺点是它可能不足以完成特定任务。
A *可能*第一种形式的缺点是它可能*
表现较差。另一个是它需要你
记得在完成它时删除它。
-Mike
Ron Natalie< ro*@sensor.com>在消息中写道
新闻:3f ********************** @ news.newshosting.com ...
garyolsen < GA ******* @ yahoo.com>在消息中写道
新闻:l6 ********************** @ bgtnsc05-news.ops.worldnet.att .net ...对于一个类MyClass,有两种实例化对象的方法:
1. MyClass * MC =新的MyClass();
2. MyClass MC;
一般来说,什么时候应该使用1和2?什么是使用它们的优点/缺点?
当#2不够时使用#1。
>
你是否想澄清一下#2何时不够?谢谢!
For a class, MyClass, there are two ways to instantiate an object:
1. MyClass *MC = new MyClass();
2. MyClass MC;
In general, when should you have to use 1 and when 2? What''re
advantages/disadvantages of using either?
Thanks!
"garyolsen" <ga*******@yahoo.com> wrote in message news:l6**********************@bgtnsc05-news.ops.worldnet.att.net...For a class, MyClass, there are two ways to instantiate an object:
1. MyClass *MC = new MyClass();
2. MyClass MC;
In general, when should you have to use 1 and when 2? What''re
advantages/disadvantages of using either?
Use #1 when #2 isn''t enough.
"garyolsen" <ga*******@yahoo.com> wrote in message
news:l6**********************@bgtnsc05-news.ops.worldnet.att.net...For a class, MyClass, there are two ways to instantiate an object:
1. MyClass *MC = new MyClass();
2. MyClass MC;
In general, when should you have to use 1 and when 2?
In general, use the second form, use the first when you must.
What''re
advantages/disadvantages of using either?
The only disadvantage I can think of for the second form
is that it might not be sufficient for a particular task.
A *possible* disadvantage of the first form is that it *might*
have poorer performance. Another is that it requires you to
remember to ''delete'' it when done with it.
-Mike
Ron Natalie <ro*@sensor.com> wrote in message
news:3f**********************@news.newshosting.com ...
"garyolsen" <ga*******@yahoo.com> wrote in message
news:l6**********************@bgtnsc05-news.ops.worldnet.att.net...For a class, MyClass, there are two ways to instantiate an object:
1. MyClass *MC = new MyClass();
2. MyClass MC;
In general, when should you have to use 1 and when 2? What''re
advantages/disadvantages of using either?
Use #1 when #2 isn''t enough.
Would you mind to clarify a little bit about when #2 isn''t enough? Thanks!
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