关于删除[]与仅删除的问题 [英] Question on delete [] vs just plain delete

问题描述

我是c ++的新手。我最近花了大量的时间来解决一个看似无害的代码片段。虽然我把这段代码缩小了作为罪魁祸首，但我不明白为什么。可以

一些大师有助于启发我吗？谢谢。


//我创建了一个指向对象指针的指针数组：


Object ** obs = new Object * [9] ;


//之后我填充这个数组：


for（int i = 0; i< 9; i ++）{

obs [i] = new Object（i）;

}


//使用它们后我删除了数组：


for（int i = 0; i< 9; i ++）{

删除obs [i];

}


删除[] obs;


删除obs; //这就是问题，在执行程序期间

被绞死。


显然，上面引起了未定义的行为。但我不知道为什么

我不应该这样做。再次感谢您的分享！


干杯，

Damon

解决方案

" DamonChong" <所以******** @ excite.com>在消息中写道

新闻：11 ********************* @ c13g2000cwb.googlegro ups.com ...

我是c ++的新手。我最近花了大量时间来解决一条看似无害的代码。虽然我把这段代码缩小为罪魁祸首，但我不明白为什么。可以帮助一些大师帮我启发吗？谢谢。


虽然大师回答了更难的问题，但我会把这个问题写下来。

//我创建了一个指向对象指针的指针数组：

///////////太好了，你已经分配了一系列指向对象的指示

//之后我填充了这个数组：

for（int i = 0; i< 9; i ++）{
obs [i] = new Object（i）;


///////////现在你已经分配了这些物品。 //

//使用它们后我删除了数组：

for（int i = 0; i< 9; i ++）{
删除obs [i] ;


///////////现在你已经解除了对象的分配。

}

删除[] obs;


///////////现在你已经取消了数组。

///////// //好所以你已经解除了你分配的所有东西。什么都没有

留下来解除分配。


///////////然而......
删除obs; //这就是问题，在执行过程中程序挂了。

///////////所以上一行挂起了你要解除分配的东西

你不应该

你好Damon


Efrat已经回答了你的帖子，但我建议你不要使用

new / delete作为新手C ++程序员。而是专注于标准库

并且不要使用指针。

指针很难，最好不要使用直到你理解基础知识
$ b $ C ++的b - 包括标准库。通过这条路线，您还可以了解现金C ++中实际指针的使用情况。


/ Peter

DamonChong <所以******** @ excite.com> skrev i en meddelelse

news：11 ********************* @ c13g2000cwb.googlegro ups.com ...

我是c ++的新手。我最近花了大量时间来解决一条看似无害的代码。虽然我把这段代码缩小为罪魁祸首，但我不明白为什么。可以帮助一些大师帮我启发吗？谢谢。

//我创建了一个指向对象指针的指针数组：

对象** obs = new Object * [9];
//之后我填充这个数组：

for（int i = 0; i< 9; i ++）{
obs [i] = new Object（i）;
}

//使用它们后我删除了数组：

for（int i = 0; i< 9; i ++）{
删除obs [i ];
}
删除[] obs;

删除obs; //这就是问题，在执行过程中程序挂了。

显然，上面引起了不确定的行为。但我不知道为什么我不应该这样做。再次感谢您的分享！

干杯，
Damon

2005年1月29日01:39:32 - 0800，DamonChong < so ******** @ excite.com>

写道：

delete [] obs;

删除obs; //这是问题，在执行程序期间

通常你在你分配的任何数组上使用delete []告诉

编译器那个ptr你正在删除是一个数组。


它只是你需要学习的那些不明显的c ++规则之一:)


无论如何我建议你使用vector<>而不是数组因为它

更安全，更方便。查看在线帮助/书籍以获取信息。

STL一般可以帮到你很多。


/ ajk

- -

这些是我的原则。如果你不喜欢他们，我还有其他人。

Groucho Marx。

Hi,

I am new to c++. I recently spend an enormous among of time
troubleshooting a seeminly innocuous piece of code. Although I narrow
down this piece of code as the culprit but I don''t understand why. Can
some guru help to enlighten me? Thank you.

// I created an array of pointers to object pointers:

Object ** obs = new Object * [9];

// After that I populate this array:

for(int i=0; i<9; i++){
obs[i] = new Object(i);
}

// After using them i deleted the array:

for(int i=0; i<9; i++){
delete obs[i];
}

delete [] obs;

delete obs; // this is the problem, during execution the program
hanged.

Apparently, the above caused undefined behaviour. But I don''t know why
i shouldn''t do that. Thanks again for any sharing!

Cheers,
Damon

解决方案

"DamonChong" <so********@excite.com> wrote in message
news:11*********************@c13g2000cwb.googlegro ups.com...

Hi,

I am new to c++. I recently spend an enormous among of time
troubleshooting a seeminly innocuous piece of code. Although I narrow
down this piece of code as the culprit but I don''t understand why. Can
some guru help to enlighten me? Thank you.
While the gurus answer more difficult questions, I''ll field this one.

// I created an array of pointers to object pointers:

Object ** obs = new Object * [9];
/////////// Great, you''ve allocated an array of pointers to Object

// After that I populate this array:

for(int i=0; i<9; i++){
obs[i] = new Object(i);
/////////// And now you''ve allocated the objects. }

// After using them i deleted the array:

for(int i=0; i<9; i++){
delete obs[i];
/////////// Now you''ve deallocated the objects.
}

delete [] obs;
/////////// And now you''ve deallocated the array.
/////////// Good. So you''ve deallocated everything you''ve allocated. Nothing
left to deallocate.

/////////// and yet....
delete obs; // this is the problem, during execution the program
hanged.

/////////// So the previous line hangs since you''re deallocating something
which you shouldn''t

Hi Damon

Efrat already answered your post, but I will recommend you do not use
new/delete as a newbie C++ programmer. Instead focus on the standard library
and just don''t use pointers.
Pointers are difficult and better not used until you understand the basics
of C++ - including the standard library. By going this route, you will also
learn how little use there actually is of pointers in modern C++.

/Peter
"DamonChong" <so********@excite.com> skrev i en meddelelse
news:11*********************@c13g2000cwb.googlegro ups.com...

Hi,

I am new to c++. I recently spend an enormous among of time
troubleshooting a seeminly innocuous piece of code. Although I narrow
down this piece of code as the culprit but I don''t understand why. Can
some guru help to enlighten me? Thank you.

// I created an array of pointers to object pointers:

Object ** obs = new Object * [9];

// After that I populate this array:

for(int i=0; i<9; i++){
obs[i] = new Object(i);
}

// After using them i deleted the array:

for(int i=0; i<9; i++){
delete obs[i];
}

delete [] obs;

delete obs; // this is the problem, during execution the program
hanged.

Apparently, the above caused undefined behaviour. But I don''t know why
i shouldn''t do that. Thanks again for any sharing!

Cheers,
Damon

On 29 Jan 2005 01:39:32 -0800, "DamonChong" <so********@excite.com>
wrote:

delete [] obs;

delete obs; // this is the problem, during execution the program

normally you use delete [] on any array you allocate to tell the
compiler that the ptr you are deleting is an array.

it is just one of those not obvious c++ rules you need to learn :)

in any case I would suggest you use vector<> instead of array since it
is safer and more convenient. check up the online help/book for info.
STL in general can help you a lot.

/ajk
--
"Those are my principles. If you don''t like them I have others."
Groucho Marx.

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