g****c
发帖数: 299 | 1 google earth 3d is 3d for earth not for map.
ms virtual earth is 3d of map. you can make a virtual tour in New york
street |
|
r****y
发帖数: 26819 | 2 微软这个东西叫做virtual earth 3D，而你却能知道这是3D for map，看来你不是微软的
人也是微软的粉丝啊。
这个virtual tour也没看出和google earth的本质不同出来。何况用的是google的老地
图。基本上就是在一个二维地图上加一个鼠标操作的投影界面，外加一些高层建筑的数
据。 |
|
q**j
发帖数: 10612 | 3 thanks. i mean i am now running pcmanx in virtual desktop2 and i want to
drag it to virtual desktop 1. |
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a********e
发帖数: 78 | 4 在windows machine 上用 virtualbox 装了ubuntu， 请问怎样把windows目录里的文件
转到virtual machine 的目录里。在C 盘里找到virtual box->Hard disks的木录，创
建的机器是以vdi 结尾的，打不开。 |
|
l*****b
发帖数: 82 | 5 I have a remote linux server. What commands I could use to check if the
linux is running on a virtual server? And the system resource allocation
info for the virtual servers?
Thank you |
|
v*****r
发帖数: 1119 | 6 不像 windows, 32bit memory limit 对 Linux 没有太大的影响。
Linux 下的 32bit memory limit 是 4G Virtual address space per process, low
memory 840M reserved for kernel, PTE etc. 实际的 physical memory 可以扩展到
64GB depending on hardware platform.
所以在 Linux 下，32 bit 唯一的问题就是 process 不能一口咬 大于 4G 的 memory
, 但也有 workaround. |
|
d**e
发帖数: 863 | 7 How to understand this comment on virtualization?
"ARM chips are much cheaper than general-
purpose and specialty microprocessors and,
due to their low cost, there is no need to
virtualize, reducing complexity." |
|
d**e
发帖数: 863 | 8 How is virtualization supported by CPU design?
I mean, what extra must be done so that a particular
CPU chip supports virtualization? |
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S*A
发帖数: 7142 | 9 No must. The early x86 CPU can still run virtualization
using binary translations. VMware does that.
The recent CPU change make virtualization easier in a
sense. Not as easy as most people thing though. |
|
d**e
发帖数: 863 | 10
Thank you, actually I asked one question before,
http://www.mitbbs.com/article_t0/Linux/31257399.html
as I read a recent magazine article, ARM
defended its decision to not support virtualization.
That makes me wonder what more are needed to support virtualization. |
|
J****0
发帖数: 2400 | 11 我已经从了wubi了，用virtual PC和virtual box （这个也可以全屏）跑ubuntu实在太
慢。 |
|
J****0
发帖数: 2400 | 12 我已经从了wubi了，用virtual PC和virtual box （这个也可以全屏）跑ubuntu实在太
慢。 |
|
p*****b
发帖数: 291 | 13 想把一台SERVER(32GB,32COREs)（ Redhat)virtualize。请推荐免费的REDHAT上带图形
管理界面的VIRTUALIZATION解决方案。 |
|
w*********t
发帖数: 319 | 14 Could you tell me any situation not to use virtual destructor? Usually I use
virtual destructor in derived classes.
This might related embedded C++ software.
Thanks. |
|
c****e
发帖数: 1453 | 15 Statically, I think you can count the number of virtual functions and times
4.
Here is my guess:
suppose we want to know the vtable size of class B.
build D,
class D : public B
{
virtual void test(){}
};
now, in the memory:
D:
+0: pointer to vtable
vtabble:
... v functions in class B
test()
D * pd= new D;
void (*p)()=pd->test;
char * vtable_base=(char *)(*(int *)pd);
vsize=(char *)p - vtable_base; |
|
c*****g
发帖数: 119 | 16 2.是说：程序运行的时候没法知道到底一个object有几个virtual functions。如果
class里virtual function改变了，其他的code相应地都得变。
the |
|
W*********g
发帖数: 409 | 17 不可行。首先vptr在哪不清楚，微软是放在前面，但是更直接的方法是在后面，如果是
这样，对于derived class来说vptr就在中间了，这还没有考虑multiple inherit（多
个vtbl） 和virtual inherit（virtual base class有自己的vtbl）。
其次vtbl里还有其他东西，比如typeid。有些实现会把this pointer adjustment
offsets放在vtbl里。 |
|
b***y
发帖数: 2799 | 18 For base classes, it is ok to have more virtual functions because derived
classes may need to customize these functions. For concrete classes, they
may have their own nonvirtual functions that are not supposed to be
overrided.
Also, if you declare a function as virtual, it can't be a inline function. |
|
g*****g
发帖数: 34805 | 19 Efficiency is the only benefit of non-virtual function.
By making all non-static functions virtual, Java simplifies
its syntax a lot. |
|
F**********r
发帖数: 237 | 20 The more virtual functions you declare, more places you need to worry about
for complicated overriden behavior...You probably should only declare
virtual when it's really necessary |
|
g*****g
发帖数: 34805 | 21 On the contrary, it's more complicated in C++ way.
Let's say Child inherits from Parent, both have a do function.
Parent a = new Child();
Child b = new Child();
In C++, a.do() will call Parent.do(), b.do() will call Child.do() if
do() is not virtual.
but both a and b are an instance of Child in runtime. This can
be confusing, you have to check declaration of Parent before you know
whether it's virtual and which function is called.
In java, it's always calling Child.do().
about |
|
b***y
发帖数: 2799 | 22 ☆─────────────────────────────────────☆
gebitan (she is coming soon...........) 于 (Thu Jul 21 16:54:29 2005) 提到:
I always thought that a pure virtual function can not have implementation. But
after I read scott meyers's effective C++ (2nd ed) item 36, he did make the i
mplementation for the pure virtual function. but I can not understand why he u
se it.What's the advantage of using it? Anybody can explain it a little bit?
Thanks a lot.
☆─────────────────────────────────────☆
crystalike |
|
g****g
发帖数: 310 | 23 tried 12 virtual funcs vs 1 virtual funcs,
NO DIFFERENCE! |
|
b***y
发帖数: 2799 | 24 ☆─────────────────────────────────────☆
supervita (vita) 于 (Mon Nov 24 23:16:16 2008) 提到:
class A
{
virtual void g() {cout<<"A";}
virtual void f() {g();}
};
class B : public A
{
void g() {cout<<"B";}
void f() {A::f();}
};
B iob;
iob.f();
请问这段代码输出的结果是A还是B？并请简要讲解下原因。。 多谢！！
☆─────────────────────────────────────☆
thrust (祝阳阳早日康复) 于 (Mon Nov 24 23:17:33 2008) 提到:
自己试试不就知道了...
☆─────────────────────────────────────☆
supervita (vita) 于 (Mon Nov 24 23:47:27 2008) 提到: |
|
b***y
发帖数: 2799 | 25 ☆─────────────────────────────────────☆
gebitan (job, job) 于 (Thu Sep 1 17:08:27 2005) 提到:
I got an question like this:
class B{public: virtual ~B()=0;};
class D : public B{};
Is there anything wrong?
The answer is nothing wrong. But I can not understand why put destructor as
pure virtual function.
☆─────────────────────────────────────☆
wy (Parry Otter) 于 (Thu Sep 1 17:25:38 2005) 提到:
so that its concrete derive must implement a destructor ya. ft
☆────────────────────────────────── |
|
i***h
发帖数: 12655 | 26 class Base {
void foo();
};
class Derived: Base {
virtual void foo();
};
这个和把 virtual 放在 Base 里等价么? |
|
i***h
发帖数: 12655 | 27 也就是说Base function 不是 virtual 的
对我上面的例子来说等于没有virtual
(假定没有class 继承 Derived)
比如
Base *b = new Derived;
b->foo();
还是会调用 Base::foo()
这么理解对么? 谢谢
class |
|
d****b
发帖数: 25 | 28 c++中 overload << operator 是用 friend function, 但是如果在derived class 中
也overload <<, 因为是friend, 不能virtual, 怎么搞呢, 是不是只能是自己定义一个
virtual void show() 的函数? 谢谢大家 |
|
s****n
发帖数: 1237 | 29 下面这段代码输出的是 Class B func1 x = 2， 我有几个疑问
1. 为啥调用的是B的func1但是x却是用了A的缺省值？
2. B的func1我特地设为private，为啥还是能调用？我试过直接B ojbB，就不能用ojbB
.func1();
3. 这里面涉及哪些相关的知识点，有什么好的quick tutorial可以推荐。
谢谢。
#include
using namespace std;
class A
{public:
virtual void func1 (int x = 2) {
cout << "Class A func1 x = " << x << "\n";
}
};
class B: public A
{private:
virtual void func1 (int x = 8){
cout <<"Class B func1 x = " << x << "\n";
}
};
void main () {
A *aPtr = new B;
aPtr -> func |
|
p****o
发帖数: 1340 | 30 1. values of default arguments are resolved at compilation time
2. a function is virtual is virtual, and the "private" clause only
constraints the use of class B outside B.
kind of feeling strange at first, and it makes sense eventually.
ojbB |
|
P********e
发帖数: 2610 | 31 机子空闲的人可以试试
这样：
class A
{
virtual void f1(){};
.
.
.
virtual void f129(){}
};
void (*A::fp)() = &A::f129();
A a;
(a.*fp)(); |
|
g*********s
发帖数: 1782 | 32
is
virtual). it
pointer,
is
assume such an implementation to support static virtual:
for b->x(), we first know "this" has dynamic type D, then we lookup
class D's static method list to find x().
here i don't see any problem on prototype uniqueness...
of course, the principle of programming board is "trust is always right
on c++" and i honor it. :) but i just want to have a deeper
understanding through the discussion. |
|
d*****l
发帖数: 8441 | 33 【 以下文字转载自 Windows 讨论区 】
发信人: digital (你是疯儿我是傻？), 信区: Windows
标 题: Windows Virtual Machine编程？
发信站: BBS 未名空间站 (Thu Aug 11 22:48:16 2011, 美东)
比如从host os启动virtual PC中的程序（包括guest application的编程），然后等待
其运行完毕并退出啥的。
有啥资料、例子（语言不限）给推荐一下？
谢谢！ |
|
c**********e
发帖数: 2007 | 34 【 以下文字转载自 JobHunting 讨论区 】
发信人: careerchange (Stupid), 信区: JobHunting
标 题: C++ Q98: Call member function in virtual function
发信站: BBS 未名空间站 (Fri Oct 21 20:04:02 2011, 美东)
What is the output of the following code? Why?
#include
using namespace std;
class base {
public:
void pay() { cout << "Base::pay" << endl; }
virtual void eat() { pay(); }
};
class derived: public base {
public:
void pay() { cout << "Derived::pay" << endl; }
};
void main() {
base* p = new derived;
... 阅读全帖 |
|
c**********e
发帖数: 2007 | 35 1. What are the disadvantages of any of declaring a destructor virtual?
2. Do you think that C++ should simply default to making all destructor
virtual? |
|
c**********e
发帖数: 2007 | 36 1. Is it possible to call a pure virtual method that has not been defined?
2. Is it possible to call a pure virtual method that has been defined? |
|
x*p
发帖数: 4 | 37 Got the message of "Virtual memory exceeded in 'new'".
The message is not from the source code anywhere.
Is this message coming from the O.S.? The machine I am
using is a DEC Alpha with 4GB of RAM and tons of virtual
space. I expected my program to take a huge amount of
memory, but 4GB should be large enough.
BTW, There is no other processes running on the machine
at the same time. Anyone has some good insight?
Many thanks! |
|
l***h
发帖数: 139 | 38 i have 1G memory. my virtual memory is set to like 300M.
you always need to set the min and max the same to improve performance,
to prevent windows from resizing virtual memory -- otherwise, too many frac-
tions. |
|
N*********r
发帖数: 40 | 39 Agree. Another tip is to defrag HD before setting virtual memory size
to a fix value, and if the computer allows (enough physical memory),
disable the virtual memory (or set to 0 size) before the defragment,
then set it back. |
|
f******g
发帖数: 111 | 40 seriously not a joke. i have been using it on my 2G Hz 2G RAM machine. it runs
well.
the problem is its increasing virtual disk which slows down the speed when you
use it for months time.
whether it fits your need depends on your application. You can use virtual PC
in many ways:
1/ host a topology on a single box; server consilidation
3/ remotely control shutting down a server and reboot to another partition to
do maintenance tasks.
4/ run hybrid systems, Windows/Linux/Unix on a single box
5/ Fa |
|
B******y
发帖数: 9065 | 41 我看了新出的Virtual PC 2007的说明，想问一下是否如果我装了一台64位的机器，然
后在64位的Vista里面装了Virtual PC以后，就可以安装32位的XP，那么原来的一些应
用软件就都可以在XP里面运行了？会不会还是有32位与64位之间的冲突问题？多谢了。 |
|
m*t
发帖数: 843 | 42 I use firefox and maxthon to open many webpages at same time
then from time to time, vista complain virtual mem (auto managed) is too low
and some program starts to shutting down due to that
Then I increase the virtual mem to 100GB, after a week or so, it starts to
complain again becasue all 100GB is filled up.
This sucks
Any idea?
3xs |
|
b****s
发帖数: 1300 | 43 报告一下：
VirtualBox比Virtual PC好得不是一点点。首先可控性好很多，其次Guest OS的运行速
度几乎是Native的，而在Virtual PC 2007同样配置下，则慢多了，而且总是出问题。
另外，VB的seamless mode简直太棒了（当然还不是很完美）。
VMware没有试，考虑到安装占用空间太大。 |
|
b*********s
发帖数: 3863 | 44 thanks,just figured out
actually you can not locate it that way.
it should be c:/users/xxx/appdata/local/microsoft/windows virtual machine/
*.vhd
took me a while
Then use my computer -> manage -> action -> mount that x.vhd to mount the
virtual hard drive to view and modify... |
|
|
|
|
w*******y
发帖数: 60932 | 48 Valid 2/18/12
Dell Inspiron Laptop - Intel Core i3 Processor, 3GB Memory, 320 GB Hard
Drive - $349.99 + Shipping & Handling
Model: I15N-1908BK
o IntelCore(TM) i3-380M processor (3MB L2 cache and 2.53GHz processor
speed)
o3GB DDR3 memory
o 15.6" WLED high-definition display
o 320GB hard drive (5400 rpm)
o IntelHD graphics
o Built-in 0.3MP webcam
Online Offer. Limited Quanities
Also, M-Audio - Venom 12-Voice Virtual Analog Synthesizer (White):
http://www.bestbuy.com/site/M-Audio - Venom 12-Voice ... 阅读全帖 |
|
w*******y
发帖数: 60932 | 49 Free ebooks: Great content from Microsoft Press that won't cost you a penny
the following page contains links to individual titles:
Link:
http://iway.org/9601251
Introducing Microsoft SQL Server 2012
Introducing Microsoft SQL Server 2008 R2
Introducing Windows Server 2008 R2
Understanding Microsoft Virtualization Solutions, From the Desktop to the
Datacenter
Microsoft Office 365: Connect and Collaborate Virtually Anywhere, Anytime
First Look Microsoft Office 2010
Security and Privacy for Microso... 阅读全帖 |
|
O**********g
发帖数: 3962 | 50 也不算virtual，你可以在家一边喝咖啡一边视频 |
|
