Hey,

please consider the following:

#if DEBUG
#define SOMEMACRO(type, name, value) (type) (name) = (value)
#else
#define SOMEMACRO(type, name, value) #define (name) (value)
#endif

If I define DEBUGging, i want the variable (name) to be a variable, but
if not, I want it to be a constant. When I compile this, the preprocessor
starts complaining at the fourth line, because of the second #define. Is
this OT here? And if not, how should I solve this?

the d0ct0r

Hello. When I consult the ISO C++ standard, I notice that in
paragraph 3.6.2.1, the standard states:
"Objects with static storage duration shall be zero-initialized before
any other initialization takes place."

Does this mean all non-local objects will be zero-initialized before
they are initialized by their initializers(if they have)? For example:

int g_var = 3;
int main() {}

Will g_var be first initialized to zero, then to 3?

why virtual destructors are possible but virtual constructors are not?

Hi all,
Newbie question here wrt defining a class that will work on bits read
from a binary file. How would you go about doing it? As an example
please look at the structure of my data given below. The data comes in
40 byte packets via stdin or a binary file.
my_Data_pkt(){
syncByte (8bits)
XML_type (2bits)
XML_subtype (2bits)
record_value (3bits)
playout_flag (1bit)
if (playout_flag=='1') {
playout_length (8bits)
for (i=0; i< playout_length; i++){
playout_data
}
}
payload to fill the rest of the 40 bytes
}
How would this be defined as a class? ...

Sorry about the beginners question

In the header file, each time you define a class or function, it has
to be followed by a semicolon.
But in the source file, the functions do not have to be followed by
semicolon.

What is the reason for this?

Thanks

class Number
{
public:
Number(int num=0):private_number(num) {};

void compare(const Number & another_number_class) const
{
if(this->private_number == another_number_class.private_number)
std::cout<<"the two classes have the same numbers !"< else
std::cout<<"the two classes have different numbers !"< };

private:
int private_number;
};

In this class Number, the function "compare" can reach the private
data member of both current object and "the parameter object". Is this
because both objects belong to the same class?

stonny

I'm using AdaBoost on optical flow data to learn to recognize human
actions. I've split my optical flow data into 5 channels (positive x,
negative x, positive y, negative y, and 'zero'). I know how to use
AdaBoost on a single channel, but I'm not sure how to combine the 5
channels to form a better classifier. Do I run AdaBoost on each
channel, and then pass the 5 outputs to another AdaBoost, or should I
simply concatenate the 5 channels and run AdaBoost once on all of
them?

Thanks,
Mark

Hi,

I want to provide a specialization of a class for any type T that is a
std::map.

template
class Foo
{
// ...
};

template
class Foo >
{
// ...
};

It seems to work - is this the correct way to do this?

Foo uses the normal template, but Foo > for any
types of T1 and T2 uses the specifalization?

Thanks

Is it possible to privately inherit from a class while exposing as one
of the class' base classes?

For example, say I have the following classes,

class Widget { };

class Button : public Widget { };

Now I want to create a MyButton class that privately inherits from
Button for its implementation, but only exposes itself as a Widget.
In other words, I don't want the users of MyButton to be tinkering
with the Button part without going through the MyButton interface.

The kicker is that the code for Widget and Button may not be modified,
so I cannot make Button virtually inherit Widget and use proper
multiple inheritance.

Any takers?

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