Re: Question about reading and writing to a file - C / C++ / MFC Discussion Boards

Re: regular expression library for win32 api c or c++

LunaticFringe9-Jan-10 11:56

LunaticFringe

9-Jan-10 11:56

You should probably go with the TR1 implementation mentioned below; it'll be less likely to be deprecated.

L u n a t i c F r i n g e

Re: regular expression library for win32 api c or c++

Jayapal Chandran10-Jan-10 8:14

Jayapal Chandran

10-Jan-10 8:14

Yeah. i have to. thank you.

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Re: regular expression library for win32 api c or c++

Graham Shanks8-Jan-10 10:39

Graham Shanks

8-Jan-10 10:39

Boost[^] contains a regular expression library called Regex.

The advantage of using this is that Regex is also part of TR1[^], so that it will be part of the C++ standard in the future and will be included as part of the standard library in upcoming C++ compilers (it was include in the April 2008 Visual Studio 2008 Feature Pack and I believe that gcc 4.0 supports it as well).

Graham

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Re: regular expression library for win32 api c or c++

Nemanja Trifunovic8-Jan-10 12:07

Nemanja Trifunovic

8-Jan-10 12:07

If you are using VC++ 2008 (or even 2005 with the feature pack), you already have TR1 regex installed. Here is a small tutorial.[^]

utf8-cpp

Re: regular expression library for win32 api c or c++

Jayapal Chandran9-Jan-10 5:39

Jayapal Chandran

9-Jan-10 5:39

Thank you for all the above replies... this it totally new so it would take some time for me to ...

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Question about reading and writing to a file

amichai228-Jan-10 6:25

amichai22

8-Jan-10 6:25

I am trying to write a triple vector to a file and then read the file back into the triple vector. When I try to read the file back after its been saved the first fifty values come out correct but the rest of the values are garbage. I'd be really appreciative if someone could help me out here. Thanks a lot!

File declaration:

fstream memory_file("C:\\Users\\Amichai\\Pictures\\output.txt", ios::in | ios::out);

The write function:

void save_training_data(fstream &memory_file, vector<vector<vector<long double> > > &training_data)
 {
   int sizeI = training_data.size();
   memory_file.write((const char *)&sizeI, sizeof(int));
   for (int i=0; i < sizeI; i++)
   {
       int sizeJ = training_data[i].size();
       memory_file.write((const char *)&sizeJ, sizeof(int));
       for (int j=0; j < sizeJ; j++) 
       {
           int sizeK = training_data[i][j].size();
           memory_file.write((const char *)&sizeK, sizeof(int));
           for (int k = 0; k < sizeK; k++)
           {
               int temp;
               temp = (int)training_data[i][j][k];
               memory_file.write((const char *)&temp, sizeof(int));
           }
       }
   } 
 }

The read function:

void upload_memory(fstream &memory_file, vector<vector<vector<long double> > > &training_data)
{
     memory_file.seekg(ios::beg);
     int temp=0;
     int sizeK, sizeJ, sizeI; 
     memory_file.read((char*)&sizeI, sizeof(int));
     training_data.resize(sizeI);
     for (int i=0; i < sizeI; i++)
     {
           memory_file.read((char*)&sizeJ, sizeof(int));
           training_data[i].resize(sizeJ);           
           for (int j=0; j < sizeJ; j++)
           {
               memory_file.read((char*)&sizeK, sizeof(int));
               training_data[i][j].resize(sizeK);
               for (int k = 0; k < sizeK; k++)
               {
                    memory_file.read((char*)&temp, sizeof(int));
                    training_data[i][j][k]=temp;
               }
           }
     } 
}

Thanks again,
Amichai

Re: Question about reading and writing to a file

amichai228-Jan-10 6:28

amichai22

8-Jan-10 6:28

Just solved the problem.
The file declaration needs the ios::binary specification.

Re: Question about reading and writing to a file

Nelek8-Jan-10 6:38

Nelek

8-Jan-10 6:38

5 for self-solved and posting the solution Smile | :)

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string array

CODEPC8-Jan-10 5:08

CODEPC

8-Jan-10 5:08

Hi
I need declare a wchar_t array which should looks like:

strarray[1] = "ddgfdgd";
strarray[2] = "ddgfdgd ... sada";
...
strarray[n] = "ddgfdgd";

The "n" is variable.

wchar_t** strarray= new wchar_t[n][];

is not correct.

Any suggestion?

Re: string array

Richard MacCutchan8-Jan-10 5:28

Richard MacCutchan

8-Jan-10 5:28

You need to allocate pointers to wchar_t like so:

wchar_t** strarray = new wchar_t*[n];

I tend to use the Windows types for character pointers like so:

LPWSTR* strarray = new LPWSTR[n];

[edit]Add ref to LPWSTR[/edit]

Re: string array

Rajesh R Subramanian8-Jan-10 6:07

Rajesh R Subramanian

8-Jan-10 6:07

While Richard has answered your query, you'll be much better off using an array of std::string objects (that is - if you don't want to use something like a vector). This means no hand crafted memory allocation or management, plus no dangling pointers or other pointer related failure modes waiting to crash your application.

“Follow your bliss.” – Joseph Campbell

Re: string array

Cedric Moonen8-Jan-10 7:35

Cedric Moonen

8-Jan-10 7:35

A std::wstring in his case Wink | ;)

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Re: string array

Rajesh R Subramanian8-Jan-10 7:51

Rajesh R Subramanian

8-Jan-10 7:51

Ah, the joys of being a nitpick. Smile | :)

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Re: string array

Cedric Moonen8-Jan-10 8:06

Cedric Moonen

8-Jan-10 8:06

Rajesh R Subramanian wrote:
Ah, the joys of being a nitpick.

Rajesh R Subramanian wrote:
OT: How's married life? Probably too early to comment?

Honnestly, there's not much differences... We were already living together for 3 years so, not much of a change.

Cédric Moonen
Software developer

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Re: string array

Richard MacCutchan8-Jan-10 8:59

Richard MacCutchan

8-Jan-10 8:59

Cedric Moonen wrote:
Honnestly, there's not much differences

Don't tell her that...

Re: string array

CPallini9-Jan-10 4:56

CPallini

9-Jan-10 4:56

Richard MacCutchan wrote:
Cedric Moonen wrote:
Honnestly, there's not much differences

Don't tell her that...

Ouch, I already told her! Big Grin | :-D

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Chesnokov Yuriy8-Jan-10 5:04

Chesnokov Yuriy

8-Jan-10 5:04

Will be there any problems with static libs linkage and what function will be linked and executed?

There are 2 lib files generated from the same project:

1) somelib.lib
2) somelib_updated.lib

Both contain the same function names, but updated has some enhanced functionality, but all the function names are the same.

3) oneimplementation.lib has static linkage with somelib.lib
4) otherimplementation.lib has static linkage with somelib_updated.lib

In 3) it provides myfunction() which uses somelib.lib code
In 4) it provides myfunction_updated() which uses somelib_updated.lib.

Thus is it targeted that due to the fact that we can not change naming in 1) and 2) we are trying to provide wrappers for them for a final exe.

The final exe build scheme is:

1) -> 3)
---------------->final exe app
2) -> 4)

Final exe linkes only to 3) and 4)

Which functions will be linked to final exe? How to make sure 1) and 2) code will be different?

Чесноков

Migounette8-Jan-10 12:40

Migounette

8-Jan-10 12:40

From your explainations, it will depend on your link command line.

in fact if you link 1 with 3 without providing 2 in the path, you library will have the code from 1.
It's because your are in static, so the library will copy the code during the link operation.

Otherwise you will have an error : duplicate symbols detected

My two cents

Chesnokov Yuriy10-Jan-10 1:34

Chesnokov Yuriy

10-Jan-10 1:34

The code is copied. I checked 3) and 4) it does contain message strings from 1) and 2) correspondingly.

But once you compile exe calling both 3) and 4) only function from 1) is called. If you compile it calling only 4) then 2) is called

Чесноков

Saurabh.Garg9-Jan-10 14:34

Saurabh.Garg

9-Jan-10 14:34

Is it possible to make oneimplementation.lib and otherimplementation.lib as DLL's?

-Saurabh

Chesnokov Yuriy10-Jan-10 1:32

Chesnokov Yuriy

10-Jan-10 1:32

I need them all to be in static libs

Чесноков

converting float from host to network order

Vishal Kumar Soni8-Jan-10 5:01

Vishal Kumar Soni

8-Jan-10 5:01

There are function to convert int and short in to network oder but not for float.
Can any one tell that how can we convert float in to network byte order?

Regards,
Vishal Soni

Re: converting float from host to network order

Moak8-Jan-10 8:36

Moak

8-Jan-10 8:36

Vishal Kumar Soni wrote:
There are function to convert int and short in to network oder but not for float.

They have never been standardised. Floats and doubles need to be serialised as described in Beej's guide to network programing: Serialization—How to Pack Data[^], e.g. simply by using sprintf() and atof(). A more elaborate variation, also described in the linked document, would be converting into a portable binary form of the IEEE 754 standard format[^].

Hope this helps.
/M

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Re: converting float from host to network order

Vishal Kumar Soni8-Jan-10 23:57

Vishal Kumar Soni

8-Jan-10 23:57

Moak,
Thanks very much!!

Regards,
Vishal Soni

Re: converting float from host to network order

Graham Shanks8-Jan-10 11:26

Graham Shanks

8-Jan-10 11:26

The following will work:

float htonf(float value)
{
  float result;
  char* pSource = reinterpret_cast<char*>(&value);
  char* pDest = reinterpret_cast<char*>(&result);
  pDest[0] = pSource[3];
  pDest[1] = pSource[2];
  pDest[2] = pSource[1];
  pDest[3] = pSource[0];
  return result;
}

Warning: once a value has been converted to network order do not try to use it on the host, since it is almost certainly an invalid IEEE 754 format number.

Note that the above function also converts from network to host format.

Converting doubles is similar:

double htonf(double value)
{
  double result;
  char* pSource = reinterpret_cast<char*>(&value);
  char* pDest = reinterpret_cast<char*>(&result);
  pDest[0] = pSource[7];
  pDest[1] = pSource[6];
  pDest[2] = pSource[5];
  pDest[3] = pSource[4];
  pDest[4] = pSource[3];
  pDest[5] = pSource[2];
  pDest[6] = pSource[1];
  pDest[7] = pSource[0];
  return result;
}

Graham

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