C / C++ / MFC Discussion Boards

Re: threads and their time slots.

Roger Stoltz3-Jul-09 8:39

Roger Stoltz

3-Jul-09 8:39

Souldrift wrote:
it always jumps 15,6ms forward

I doubt the granularity and accuracy of the time value returned by ::GetSystemTimeAsFileTime(). Even though the FILETIME structure is a time value where the least significant bit represents 100 nanoseconds, it doesn't mean that it has an accuracy of 100 nanosecs.
It's like looking at your watch, measuring a time with the needle showing seconds and then multiplying the value by 1,000,000 and claim you measured with microsecond accuracy.

For time measurements of this kind you should you the performance timer; ::QueryPerformanceCounter() and ::QueryPerformanceFrequency().
It will give you the best accuracy available on your hardware.
Read here[^] for more info on the high resolution performance counter.

"It's supposed to be hard, otherwise anybody could do it!" - selfquote
"High speed never compensates for wrong direction!" - unknown

How to make truncation in C++

alikalik2-Jul-09 22:06

alikalik

2-Jul-09 22:06

How can I make a trunc() function in C++,
Example:

trunc(7.1) = 7;
trunc(7.6) = 8;

Re: How to make truncation in C++

Rajesh R Subramanian2-Jul-09 22:09

Rajesh R Subramanian

2-Jul-09 22:09

What function? Just cast it to an integer. Or if you want a function:

__inline int trunc(float f)
{
  return (int)f;
}

It is a crappy thing, but it's life -^ Carlo Pallini

Re: How to make truncation in C++

alikalik2-Jul-09 22:14

alikalik

2-Jul-09 22:14

If I do it in this way, the results are:

trunc(7.1) = 7;
trunc(7.6) = 7; // fractional part is just dropped

Re: How to make truncation in C++

Rajesh R Subramanian2-Jul-09 22:16

Rajesh R Subramanian

2-Jul-09 22:16

Oh sorry, I overlooked your previous post. You can use one of those flooring or ceiling functions.

[Added] OK, Stuart just replied with a floor function at the same time. [/added]

It is a crappy thing, but it's life -^ Carlo Pallini

Re: How to make truncation in C++

Stuart Dootson2-Jul-09 22:16

Stuart Dootson

2-Jul-09 22:16

Presuming you want similar behaviour for numbers < 0

trunc(-7.1) = -7;
trunc(-7.6) = -8;

then this should work

int trunc(double d) { return floor(d+0.5); }

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

Re: How to make truncation in C++

Michael Schubert2-Jul-09 22:19

Michael Schubert

2-Jul-09 22:19

rounded_num = (int)(num + (num < 0 ? -0.5 : 0.5));

Re: How to make truncation in C++

CPallini2-Jul-09 22:36

CPallini

2-Jul-09 22:36

You call it trunc(), but that is the expected behaviour of round() function.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

Re: How to make truncation in C++

Rajesh R Subramanian2-Jul-09 22:50

Rajesh R Subramanian

2-Jul-09 22:50

I was guessing that the OP is trying to implement the functionality himself.

It is a crappy thing, but it's life -^ Carlo Pallini

Re: How to make truncation in C++

CPallini2-Jul-09 22:56

CPallini

2-Jul-09 22:56

Your guess is right, I suppose. However, OP must not give, even to his functions, deceiving names, unless, of course, he is a Klingon programmer.
Smile | :)

Re: How to make truncation in C++

KarstenK3-Jul-09 3:21

KarstenK

3-Jul-09 3:21

you are looking for a rounding function

int round(double d)
{
return (int) (d + 0.5);
}

Press F1 for help or google it.
Greetings from Germany

Re: How to make truncation in C++

Dan3-Jul-09 10:21

Dan

3-Jul-09 10:21

The FPU already does this for you.

   //! Round double to integer
inline int iround(double v){
    int retval;
    __asm fld qword ptr [v]
    __asm fistp dword ptr [retval]
    return retval;

}

//! Round double to unsigned integer
inline unsigned int uround(double v){
    unsigned retval;
    __asm fld qword ptr [v]
    __asm fistp dword ptr [retval]
    return retval;
}

Re: How to make truncation in C++

Michael Schubert3-Jul-09 12:19

Michael Schubert

3-Jul-09 12:19

Nice.

How to make a LONGLONG array ?

krish_kumar2-Jul-09 21:25

krish_kumar

2-Jul-09 21:25

Hiii,,,

The following code doesn't take .

How to make it correct?

UINT64 ui_offset;
LONGLONG ll_array[ ui_offset];

Showing constraint error....!!!

Thank u Cool | :cool:

Re: How to make a LONGLONG array ?

«_Superman_»2-Jul-09 21:30

«_Superman_»

2-Jul-09 21:30

ui_offset has to be a constant.
Try this -

const UINT64 ui_offset = <value>;
LONGLONG ll_array[ui_offset];

«_Superman_»
I love work. It gives me something to do between weekends.

Re: How to make a LONGLONG array ?

krish_kumar2-Jul-09 21:50

krish_kumar

2-Jul-09 21:50

Hiiii....

I tried with

const UINT64 ui_offset = 1000000;
LONGLONG ll_array[ui_offset];

It works properly...

Thanking you......

GetPrivateProfileString() problem

ashish8patil2-Jul-09 20:22

ashish8patil

2-Jul-09 20:22

What is woring in my following codes run time error is occuring for both code

int main()
{LPTSTR strResult;
LPTSTR strDefault=L"no";

DWORD d=255;
GetPrivateProfileString(L"data",L"Patchcab ",
strDefault,strResult,d,
L"D:\\TMP\\patchpolicy.ini");
printf("%s",strResult);

}

int main()
{
LPTSTR strResult=L"";
LPTSTR strDefault=L"no";

DWORD d=255;
GetPrivateProfileString(L"data",L"Patchcab ",strDefault,strResult
,d,L"D:\\TMP\\patchpolicy.ini");
printf("%s",strResult);
}

Re: GetPrivateProfileString() problem

«_Superman_»2-Jul-09 20:34

«_Superman_»

2-Jul-09 20:34

There is no memory allocated for the LpReturnedString parameter.
You're declaring it as LPTSTR strResult which is only a pointer.
You will need to do this -

TCHAR strResult[255];
DWORD d = 255;

Also change printf to _tprintf.

«_Superman_»
I love work. It gives me something to do between weekends.

Re: GetPrivateProfileString() problem

ashish8patil2-Jul-09 21:31

ashish8patil

2-Jul-09 21:31

thanks a lot.

STL find errors

thelonesquirrely2-Jul-09 13:34

thelonesquirrely

2-Jul-09 13:34

Hey, I think this is just a little mistake somewhere. I am new to using the STL algorithms, so i am totally botching it somehow.

My code looks like this:

typedef std::string Node;
typedef std::vector<Node> Cluster;

and down in the code i want to do this:
bool contains (const Cluster& cl, const Node& n)
{
Cluster::iterator it = find (cl.begin (), cl.end (), n);
(it == cl.end ()) ? return false : return true;
}

is that possible? or am i not allowed to do that? Thanks in advance!

Re: STL find errors

«_Superman_»2-Jul-09 16:49

«_Superman_»

2-Jul-09 16:49

Looks good except for the last return.
It should be return (it == cl.end ()) ? false : true;

«_Superman_»
I love work. It gives me something to do between weekends.

Re: STL find errors

CPallini2-Jul-09 20:48

CPallini

2-Jul-09 20:48

«_Superman_» wrote:
It should be return (it == cl.end ()) ? false : true;

return (it != cl.end());

FFY from me & Jijo. Big Grin | :-D

Re: STL find errors

«_Superman_»2-Jul-09 21:35

«_Superman_»

2-Jul-09 21:35

«_Superman_»
I love work. It gives me something to do between weekends.

Question about some code that should crash but does not (release vs. debug & VS2003 vs. VS2008)

Maximilien2-Jul-09 9:23

Maximilien

2-Jul-09 9:23

Howdy'

I have some very bad code that should crash but I'm having difficulty figuring out why it does not crash (or even give out warnings); it works in VS2003 in release&debug and in VS2008 in debug, not in release.

class Info
{
public:
	Info();
	Info(std::wstring s1, std::wstring s2);// : m_string1(_T("")),m_string2(_T("")){};
	std::wstring m_string2;
};
struct myStruct
{
	std::vector <Info*> m_JobInfoVector;
};

m_MyStruct = (myStruct*)malloc(sizeof (myStruct) );
ZeroMemory(m_MyStruct, sizeof(myStruct));
Info* p = new Info( std::wstring(_T("allo"))  );
m_MyStruct->m_JobInfoVector.clear();

Question : What happens to the vector member when the ZeroMemory is called ? and why it does not crash in debug but it does in release ?
Confused | :confused:

Thanks.
Max.

This signature was proudly tested on animals.

Re: Question about some code that should crash but does not (release vs. debug & VS2003 vs. VS2008)

Stuart Dootson2-Jul-09 10:32

Stuart Dootson

2-Jul-09 10:32

Why worry? The code is erronous, so the result of executing it is undefined. Just replace your malloc with new myStruct...and don't, just don't ever write over a class with something like ZeroMemory - it just doesn't make sense. You have constructors to initialise structs and classes in C++.

But anyway - the error is in comparison of iterators (which clear does) - in VS2008, Debug mode iterators are different to Release mode iterators unless you specifically enable iterator debugging, which probably has something to do with it.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

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