C / C++ / MFC Discussion Boards

Le@rner13-Sep-10 19:37

13-Sep-10 19:37

Hi all,

i m using COleDateTime Ctrl to find out dates.

i want to find out 2nd sat of month,

please tell me how can i do this.

thanks in advance.

Re: How can find 2nd sat of month?

Eugen Podsypalnikov13-Sep-10 20:11

Eugen Podsypalnikov

13-Sep-10 20:11

0. Set a COleDataTimeSpan object (day) to a day
1. Set a COleDataTime object (date) to the desired month of the desired year
2. Build a loop of the incrementation (date += day)
while (1(sat) != date.GetDayOfWeek()) for two times
3. Now you (date) are at the second sat Smile | :)

virtual void BeHappy() = 0;

Re: How can find 2nd sat of month?

CPallini13-Sep-10 22:59

CPallini

13-Sep-10 22:59

Saturday is 7.
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 can find 2nd sat of month?

Eugen Podsypalnikov13-Sep-10 23:23

Eugen Podsypalnikov

13-Sep-10 23:23

virtual void BeHappy() = 0;

Re: How can find 2nd sat of month?

CPallini13-Sep-10 22:58

CPallini

13-Sep-10 22:58

COleDateTime dt(year,month,1,0,0,0);
int add = 14 - dt.GetDayOfWeek();
dt += add;

Pointer Pointing to Itself?

Skippums13-Sep-10 14:45

Skippums

13-Sep-10 14:45

I have a class that acts something like the following:

class Foo {
private:
    int const (&InitPrimes() const)[3] {
        int (*const rval)[3] = new int[1][3];
        (*rval)[0] = 2;
        (*rval)[1] = 3;
        (*rval)[2] = 5;
        return *rval;
    }

public:
    int const (&primes)[3];

    explicit Foo() : primes(InitPrimes()) { }
    virtual ~Foo() { delete[] &primes; }
};

If I have the following code in a main function, all three of the cout statements print the same value:

Foo a;
cout <<  a.primes    << endl;
cout << &a.primes[0] << endl;
cout << &a.primes    << endl;

How is this possible? It seems logical that "a.primes" == "&a.primes[0]", but shouldn't "&a.primes" be a distinct value? If they are the same, then shouldn't the following contradiction be true (assume all three return value 0xF0):

Address 0xF0 (&a.primes   ) is of type "(int*)[3]" and holds the value 0xF0, the location of a.primes
Address 0xF0 ( a.primes   ) is of type " int  [3]" and holds the value 0xF0, the address of the first element in the array
Address 0xF0 ( a.primes[0]) is of type " int     " and holds the value    2, the first prime number

Clearly I am misinterpreting which of these assumptions is false, because I know that address 0xF0 can't be 0xF0 and 2 at the same time (let's not get into a discussion on simultaneity with respect to relativity). If I type

*((int*)0xF0)

into the immediate window (VS 2008), it returns 2, but then why is &a.primes == 0xF0? Any clarification on why the above is happening would be greatly appreciated. Thanks,

Sounds like somebody's got a case of the Mondays

-Jeff

Re: Pointer Pointing to Itself?

Peter_in_278013-Sep-10 19:13

Peter_in_2780

13-Sep-10 19:13

IIRC, the original C idea (almost 40 years ago) was that the "value" of an array symbol was its base address. In other words, array == &array == &(array[0]). This dates from the days when a pointer was a pointer (to anything), and void was not yet a keyword. Somewhere in a standard or pseudo-standard that I can't find right now, there is a statement to the effect that the address-of operator (&) is optional when referring to an array. I remember some fairly energetic debate when I was working on a very early non-PDP11 implementation of Unix and C.
[OT, sort of] I think this is sufficiently removed from the present message in the time dimension for considerations of simultaneity to be of probability zero. Poke tongue | ;-P

]

Cheers from an old-timer,
Peter

Software rusts. Simon Stephenson, ca 1994.

Re: Pointer Pointing to Itself?

Aescleal13-Sep-10 23:30

Aescleal

13-Sep-10 23:30

Your problem is that you say that &a.primes is of type (int *)[3]. (Actually I think you mean int (*)[3] - a pointer to an array of three ints, not an array to three pointers to int, but that's another story) It's not - it's type is int * const.

The name of an array is an alias for the address of the first element in that array. This means that:

T t[ N ];

t == &t[ 0 ];

for all T and N.

Likewise the address of an array is an alias for the first element in that array. Again this means that:

T t[ N ];

&t == &t[ 0 ];

for all T and N.

it also means that the type of &t is T * const, not (T *)[3]; as you asserted in your post.

So t, &t and &t[ 0 ] are synonyms for the same thing and *t, *&t and t[ 0 ] all refer to the same location in memory.

Cheers,

Ash

Re: Pointer Pointing to Itself?

Skippums14-Sep-10 3:46

Skippums

14-Sep-10 3:46

Alright, I think that I understand what you are saying (although I'm still confused as to why the designers of C decided to do this). The point of my post was to ensure that class Foo is correctly deallocating the member primes in it's destructor. If I understand you correctly, then all of the following should be equivalent statements, all of which result in no memory leaks:

virtual ~Foo() {
    // Select exactly one of the following
    delete[]  primes;
    delete[] &primes;
    delete[] &primes[0];
}

Is it true that all of these correctly deallocate primes in the example? Thanks,

Sounds like somebody's got a case of the Mondays

-Jeff

Re: Pointer Pointing to Itself?

Aescleal14-Sep-10 3:57

Aescleal

14-Sep-10 3:57

The best way of avoiding delete stress like this is to not bother with fiddling about with multi-dimensional arrays. Use a vector or vector of vectors and you don't have to worry about declaring it properly, sizing it or freeing it. The class does all that for you with very little overhead (bit of space, maybe some run-time cost if your optimiser isn't up to much).

Or another way is to handle the multidimensional bit yourself over a one dimensional array but that's a bit fiddlier and not the sort of thing you want to think about unless you're writing a collection class.

Cheers,

Ash

PS: All those will delete primes - just be careful of what they're pointing to. Arrays of pointers are a good way of going gaga and there's usually a better way of doing them.

PPS: The designers of C designed pointers and arrays to be very close to the hardware - which is why they're a bugger to use properly. Fortunately in C++ you don't need to use them that much, there's almost always a better alternative.

Sending HTTP Post via TCP/IP

Dustin Henry13-Sep-10 11:15

Dustin Henry

13-Sep-10 11:15

So, I'm fairly familiar with socket programming, but I have never before tried to send HTTP arguments to a web page before using WinSock.

I'm trying to duplicate the data in the following URL:
http://www.thewebsite.com/sub/database?action=authenticate&username=test&password=test

First, I am opening a socket to www.thewebsite.com on port 80. Then, I am sending the following:

<br />
std::string message = "POST /sub/database?action=authenticate&username=test&password=test";<br />
send(m_hConnection, message.c_str(), message.length(), 0);<br />

The problem is, I don't receive a response making me assume the format is incorrect since pasting the URL in a browser does return a response. Now, I'm kind of just guessing on the format to send the data in as I can't seem to find a good description online that doesn't involve a 3rd party library.

I have the following code in another thread in attempt to receive this data:

<br />
char recvbuf[MAX_BUFFER_LENGTH];        <br />
int result = recv(m_hConnection, recvbuf, MAX_BUFFER_LENGTH, 0)<br />

Any help is greatly appreciated.

Dustin

Re: Sending HTTP Post via TCP/IP

Dustin Henry13-Sep-10 11:37

Dustin Henry

13-Sep-10 11:37

Found 2 of my problems.

First, it appears there is a problem receiving on the socket from a different thread that the one that created it. Can anyone confirm this and give me a possible solution?

Second, I added "HTTP/1.0\n" after POST in my message, I receive a response on a recv line directly after the send (not in the threaded method), but now I'm getting a response of:

HTTP/1.1 400 Bad Request
Content-Type: text/html
Date: Mon, 13 Sep 2010 21:35:24 GMT
Connection: close
Content-Length: 34

<h1>Bad Request (Invalid URL)</h1>

Any ideas?

Re: Sending HTTP Post via TCP/IP

Moak14-Sep-10 0:32

Moak

14-Sep-10 0:32

Dustin Henry wrote:
Any ideas?

Looks like a violation of the HTTP RFC, when client sends a HTTP 1.0 request the server must not answer with a HTTP 1.1 response as in your example. Well, try to send a HTTP 1.1 request as shown in my post below (including a Host header line), perhaps the server understand only HTTP 1.1. What kind of web server software are you using?

/M

Chat in Europe Java | [Coffee]

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Re: Sending HTTP Post via TCP/IP

markkuk13-Sep-10 11:52

markkuk

13-Sep-10 11:52

Correct HTTP protocol[^] requires sending more than just the request line. If the service responds to pasting the URL to a browser, you must use the GET method instead of POST. The form data[^] is appended to the URL as name=value pairs separated by "&" characters.

Re: Sending HTTP Post via TCP/IP

Dustin Henry13-Sep-10 12:15

Dustin Henry

13-Sep-10 12:15

Thanks for the reply, but linking to a 176 page document is not helpful in answering my simple question. Also, if you would look at the syntax I used I do understand the name=value pairs quite well. If you look at the reply I posted to my own post, I added the correct HTTP/1.0 header and now receive a response, but not a good one. Also, using GET instead of post does not seem to make a difference.

Thanks,
Dustin

Re: Sending HTTP Post via TCP/IP

Moak14-Sep-10 0:22

Moak

14-Sep-10 0:22

Dustin Henry wrote:
I'm trying to duplicate the data in the following URL:
http://www.thewebsite.com/sub/database?action=authenticate&username=test&password=test

This would be a GET request not a POST, translated into HTTP 1.1:

GET /sub/database?action=authenticate&username=test&password=test HTTP/1.1\r\n
Host: www.thewebsite.com\r\n\r\n

Does this help? Smile | :)

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Re: Sending HTTP Post via TCP/IP

Dustin Henry14-Sep-10 7:02

Dustin Henry

14-Sep-10 7:02

Thank you, this helps a lot. Along with the GET, adding the correct formatting you've shown at the end of my request makes it work.

Thanks for the help Smile | :)

Dustin

Validating console input

Danzy8313-Sep-10 7:33

Danzy83

13-Sep-10 7:33

Hello, I getting worried over this input validation as follows:

int age(0);

while (true)
{
    cout << "\nEnter your age: ";
    cin >> age;

    if (cin.fail())
    {
        cin.clear();

        cout << "Please enter a digit (number) only.\n";
      
        continue;
    }

    // Get the newline character
    cin.get();

    break;
}

I don't get any problems when I enter a digit. In a way to validate input, I intentionally entered a letter. The test for cin.fail() is executed and the loop starts again. But when the loop restarts and gets to cin >> age, it does not wait for me to enter anything. It continues as if something has been entered, then the cin.fail() condition statements are executed again and again... I would like to know what I should do so that when the loop restarts and gets to where the application expects input, it waits for user input rather than continuing. Thanks.

Re: Validating console input

mk1488213-Sep-10 9:08

mk14882

13-Sep-10 9:08

I first thought it was so simple.

Please see this for answer: http://www.parashift.com/c++-faq-lite/input-output.html#faq-15.3[^]

Re: Validating console input

Aescleal13-Sep-10 11:10

Aescleal

13-Sep-10 11:10

You need to remove any guff that's currently gumming up the stream. Have a look here[^] for a canned solution.

The bit you're missing is at the end of the second if in the while loop.

Cheers,

Ash

delete option in IE8 address bar

inza113-Sep-10 7:04

inza1

13-Sep-10 7:04

hi,
i would like to write a control that works the same as the IE8 address bar with the auto complete option , and implement the delete that appear on each address.
in .NET i have the option of auto complete - is it also in MFC?
and regarding the delete i have no idea how to start....

thanks!!

someone?any idea?

inza122-Sep-10 4:50

inza1

22-Sep-10 4:50

should it be list box or combo box?

Calling APIs Problem In Drivers

Coder-12345613-Sep-10 7:00

Coder-123456

13-Sep-10 7:00

Hi I want to write a device driver and I need to include ntddk.h, ndis.h, ipFirewall.h and windows.h too (for calling some APIs for example MessageBox). When I compile the source file I get some errors like redefinition structures or constant values. Why? OMG | :OMG:

And tel me how I can use APIs like GetDriveType, MessageBeep, etc in drivers.
Look at these:

1>d:\winddk\7600.16385.1\inc\api\ntdef.h(1418) : error C2027: use of undefined t
ype 'LIST_ENTRY64'
1>d:\winddk\7600.16385.1\inc\api\ntdef.h(1418) : error C2227: left of '->Blink'
must point to class/struct/union/generic type
1>d:\winddk\7600.16385.1\inc\ddk\mce.h(137) : error C2079: '_MCA_EXCEPTION::Time
Stamp' uses undefined union '_LARGE_INTEGER'
1>d:\winddk\7600.16385.1\inc\ddk\wdm.h(408) : error C2011: '_M128A' : 'struct' t
ype redefinition
1>d:\winddk\7600.16385.1\inc\ddk\wdm.h(417) : error C2011: '_XSAVE_FORMAT' : 'st
ruct' type redefinition
1>d:\winddk\7600.16385.1\inc\ddk\wdm.h(456) : error C2011: '_XSAVE_AREA_HEADER'
: 'struct' type redefinition

Thanks a lot Sleepy | :zzz:

Re: Calling APIs Problem In Drivers

JudyL_MD13-Sep-10 11:07

JudyL_MD

13-Sep-10 11:07

Reza Mirabdolhagh wrote:
how I can use APIs like GetDriveType, MessageBeep, etc in drivers

short answer - you can't. It's a driver - it executes in kernel mode not user mode hence no user-mode APIs

Judy

Be wary of strong drink. It can make you shoot at tax collectors - and miss.
Lazarus Long, "Time Enough For Love" by Robert A. Heinlein

Set the RibbonComboBox to Drop List type by code

coolhem13-Sep-10 4:23

coolhem

13-Sep-10 4:23

I've created a derived class of CMFCRibbonCombobox. How to set the RibbonComboBox to Drop List type by code? the default type is Dropdown.
Thanks！

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