如何用新的测试内存分配？ [英] How to test memory allocation with new ?

问题描述

你好，


如何处理以下事项：


------>

#include< iostream>

使用命名空间std;


int main（）

{

int n = 0x7FFFFFFF;

char * pp = new char（n）;

if（pp！= NULL）{

pp [0] = 0;

pp [n-1] = 0;

cout<< "确定]; <<结束;

}否则{

cout<< " FAILED" <<结束;

}

}

------>

编译好，但是我运行它，我得到一个分段错误。我认为测试一个NULL值足够用于测试内存分配（或者

也许这是一个错误？我使用gcc（GCC）3.3.4）

问候，

jjleto

Hello,

How do I handle the following :

------>
#include <iostream>
using namespace std;

int main()
{
int n = 0x7FFFFFFF;
char *pp = new char(n);
if ( pp != NULL ) {
pp[0] = 0;
pp[n-1] = 0;
cout << "OK" << endl;
} else {
cout << "FAILED" << endl;
}
}
------>
It compiles OK, but when I run it, I get a segmentation fault. I thought
that testing a NULL value was enough for testing memory allocation (or
perhaps it is a bug ? I use gcc (GCC) 3.3.4)

Regards,
jjleto

推荐答案

" ; jjleto" < JJ **** @ laposte.net>在消息中写道

"jjleto" <jj****@laposte.net> wrote in message

你好，

如何处理以下内容：

------>
#include < iostream>
使用命名空间std;

int main（）
int n = 0x7FFFFFFF;
char * pp = new char（n ）;


这不符合您的想法。它为一个char分配内存，并且
尝试使用0x7FFFFFFF初始化它。分配数组使用 -

char * pp = new char [...];

if（pp！= NULL）{


这是一个很大的误解，即new在失败时返回NULL。事实是

它在失败时抛出std :: bad_alloc异常（除非你指定

nothrow）

pp [0] = 0;
pp [n-1] = 0;


这是您的细分错误的原因。您正在尝试写入

非法内存位置。

cout<< "确定]; << endl;
} else {
cout<< " FAILED" << endl;
}
}

Hello,

How do I handle the following :

------>
#include <iostream>
using namespace std;

int main()
{
int n = 0x7FFFFFFF;
char *pp = new char(n);
This does not do what you are thinking. It allocates memory for one char and
tries to initialize it with 0x7FFFFFFF. To allocate an array use -
char *pp = new char[...];
if ( pp != NULL ) {
This is a big misconception that new returns NULL on failure. The fact is
that it throws std::bad_alloc exception on failure (unless you specify
nothrow)
pp[0] = 0;
pp[n-1] = 0;
This is the cause of your segmentation fault. You are trying to write to an
illegal memory location.
cout << "OK" << endl;
} else {
cout << "FAILED" << endl;
}
}

Sharad

Sharad

> char * pp = new char [...];


谢谢，分段错误实际上是你给出的原因。

尽管如此，我在运行这个程序时仍然有错误（放弃

但不是段错误）


#include< iostream>

使用命名空间std;


int main（）

{

int n = 0x7FFFFFFF;

char * pp = new char [n];

if（pp！= NULL）{

pp [0] = 0;

pp [n-1] = 0;

cout<< "确定]; <<结束;

}否则{

cout<< " FAILED" <<结束;

}

}


如何用新的测试内存分配？

> char *pp = new char[...];

Thanks, the segmentation fault was actually for the reason you gave.

Nevertheless, I still have an error when running this program ("give up"
but not a segfault)

#include <iostream>
using namespace std;

int main()
{
int n = 0x7FFFFFFF;
char *pp = new char[n];
if ( pp != NULL ) {
pp[0] = 0;
pp[n-1] = 0;
cout << "OK" << endl;
} else {
cout << "FAILED" << endl;
}
}

How do I test memory allocation with new ?

" jjleto" < JJ **** @ laposte.net>在消息中写道

"jjleto" <jj****@laposte.net> wrote in message

char * pp = new char [...];

char *pp = new char[...];

谢谢，分段错误实际上是因为你给的原因。
然而，我在运行这个程序时仍然有错误（放弃
但不是段错误）

怎么做我用新的测试内存分配？

Thanks, the segmentation fault was actually for the reason you gave.

Nevertheless, I still have an error when running this program ("give up"
but not a segfault)

How do I test memory allocation with new ?

异常。你需要在try-catch块中包装new（捕获

std :: bad_alloc）。


Sharad

I told you in my earlier reply too that new throws std::bad_alloc on
exception. You need to wrap the new in a try-catch block (catching
std::bad_alloc).

Sharad

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