using printf for uchar* datatype

[Alex Blekhman]

How to use printf for uchar* datatype. For e.g., If I have
a structure
called A with one of its member as uchar* data then how do
i print the value
of data using printf??

What is it `uchar'? Unsigned shar? Wide char? You can print
wide string with `printf' with "%ls" format:

printf("Here's wide string: %ls", L"Hello");

Alex

[Giovanni Dicanio]

How to use printf for uchar* datatype. For e.g., If I have a structure
called A with one of its member as uchar* data then how do i print the
value
of data using printf??

Do you mean wchar_t * ? (i.e. Unicode UTF-16 strings)

If so, you might find the documentation and samples for printf and wprintf
to be interesting:

http://msdn2.microsoft.com/en-us/library/wc7014hz(VS.80).aspx

BTW: You should better use the "safe" versions (e.g. wprintf_s ...)

Giovanni

[Igor Tandetnik]

How to use printf for uchar* datatype. For e.g., If I have a structure
called A with one of its member as uchar* data then how do i print
the value of data using printf??

What's contained in this field? If it just contains ASCII characters,
use %s as you would for char* .

[kunal s patel]

Hi,

I am sorry for incomplete information. uchar is defined as unsigned char.
Now here's what i am doing

Within a function, I am receiving payload as function argument.

void process (uchar *pay)

Now I have structure called A with uchar data as its member. So in function
body i do the following

struct A a;
memcpy((char*)&a,(char*)pay,sizeof(A));

Now I want to print out the value of a.data. How do i do that?

Kunal

Post by Igor Tandetnik

How to use printf for uchar* datatype. For e.g., If I have a structure
called A with one of its member as uchar* data then how do i print
the value of data using printf??

What's contained in this field? If it just contains ASCII characters,
use %s as you would for char* .
--
With best wishes,
Igor Tandetnik
With sufficient thrust, pigs fly just fine. However, this is not
necessarily a good idea. It is hard to be sure where they are going to
land, and it could be dangerous sitting under them as they fly
overhead. -- RFC 1925

...

[Brian Muth]

Post by kunal s patel
Hi,
I am sorry for incomplete information. uchar is defined as unsigned char.
Now here's what i am doing
Within a function, I am receiving payload as function argument.
void process (uchar *pay)
Now I have structure called A with uchar data as its member. So in function
body i do the following
struct A a;
memcpy((char*)&a,(char*)pay,sizeof(A));
Now I want to print out the value of a.data. How do i do that?

It depends. You haven't told us whether the payload is text or binary.

If it's text and you know the length of the payload, then try:

printf ("%.50s\n", a.data); // for example if the payload is 50 chars

If it's binary, you might want to print out hex using %x, using a for loop.

Brian

[kunal s patel]

Post by Brian Muth

Post by kunal s patel
Hi,
I am sorry for incomplete information. uchar is defined as unsigned char.
Now here's what i am doing
Within a function, I am receiving payload as function argument.
void process (uchar *pay)
Now I have structure called A with uchar data as its member. So in function
body i do the following
struct A a;
memcpy((char*)&a,(char*)pay,sizeof(A));
Now I want to print out the value of a.data. How do i do that?

It depends. You haven't told us whether the payload is text or binary.
printf ("%.50s\n", a.data); // for example if the payload is 50 chars
If it's binary, you might want to print out hex using %x, using a for loop.
Brian

...

[Igor Tandetnik]

Post by kunal s patel
I am sorry for incomplete information. uchar is defined as unsigned
char. Now here's what i am doing
Within a function, I am receiving payload as function argument.
void process (uchar *pay)
Now I have structure called A with uchar data as its member. So in
function body i do the following
struct A a;
memcpy((char*)&a,(char*)pay,sizeof(A));
Now I want to print out the value of a.data. How do i do that?

What type is a.data, and what kind of data is stored there?

[Alex Blekhman]

Post by kunal s patel
Hi,
I am sorry for incomplete information. uchar is defined as
unsigned char.
Now here's what i am doing
Within a function, I am receiving payload as function
argument.
void process (uchar *pay)
Now I have structure called A with uchar data as its
member. So in function
body i do the following
struct A a;
memcpy((char*)&a,(char*)pay,sizeof(A));
Now I want to print out the value of a.data. How do i do
that?

You print one single-byte character like this:

printf("%hc", a.data);

If you want to print its numerical value, then just cast it
to `unsigned int':

printf("%u", (unsigned)a.data);


Alex

[Kenneth Porter]

Post by kunal s patel
Within a function, I am receiving payload as function argument.
void process (uchar *pay)
Now I have structure called A with uchar data as its member. So in
function body i do the following
struct A a;
memcpy((char*)&a,(char*)pay,sizeof(A));
Now I want to print out the value of a.data. How do i do that?

printf only knows about certain builtin types with unambiguous
interpretation. "unsigned char" has no implicit meaning. So you need to
assign it a meaning.

I suggest that instead of using printf, you use iostream. You then
implement an inserter (operator <<) for your struct A and render an
appropriate interpretation of the data to the stream. You can then say:

A a;
std::cout << a;

[Giovanni Dicanio]

Post by Kenneth Porter
I suggest that instead of using printf, you use iostream. You then
implement an inserter (operator <<) for your struct A and render an
A a;
std::cout << a;

To provide some code to the OP, I think Kenneth's idea is something like
this:

<code>

class A
{
public:
...

// operator<< can access private data in A
friend std::ostream & operator<<( std::ostream & os, const A & a );
};

std::ostream & operator<<( std::ostream & os, const A & a )
{
// Print data fields into os
// ... os << a.field1 ...

return os;
}

</code>

However, it seems that for localization, it is better to use the printf-like
formatting (maybe using more modern CString.FormatMessage) than <<
inserters...
(There was a thread about that on the MFC newsgroup, IIRC).

Giovanni

[Kenneth Porter]

Post by Giovanni Dicanio
However, it seems that for localization, it is better to use the
printf-like formatting (maybe using more modern CString.FormatMessage)
than << inserters...
(There was a thread about that on the MFC newsgroup, IIRC).

Or you could use C++ locales and facets. A quick google turned up this page
on the subject:

http://www.tacc.utexas.edu/resources/user_guides/pgi/pgC++_lib/stdlibug/sta
_9169.htm