C / C++ / MFC Discussion Boards

Kevin McFarlane25-Jun-06 9:03

25-Jun-06 9:03

I've no idea. I've not used C++ in any of the .NET IDEs. Any C++ I do commercially is always in VC++ 6, and I haven't done any commercial C++ for over a year now.

Kevin

.h and .cpp files

Moujan23-Jun-06 17:11

Moujan

23-Jun-06 17:11

What is the principle motivation for having .h and .ccp files in visual C++?

Thanks, Moujan

Re: .h and .cpp files

John M. Drescher23-Jun-06 17:59

John M. Drescher

23-Jun-06 17:59

Seperate the interface from the implementation.

John

Re: .h and .cpp files

Moujan23-Jun-06 20:26

Moujan

23-Jun-06 20:26

Thanks John.

Re: .h and .cpp files

ovidiucucu25-Jun-06 2:36

ovidiucucu

25-Jun-06 2:36

Just an aside note: that's not a Visual C++ issue, but a C++ one in general.

Ovidiu Cucu
Microsoft MVP - Visual C++

CRecordset problem

moodsey21123-Jun-06 16:17

moodsey211

23-Jun-06 16:17

i find it hard to inherit the class CRecordset with the class wizard. Every time i do two set of files with the same name are created. one outside the folder of my project and one inside.

can you show me another way of adding, updating, and deleting values in a database without creating a new class that inherits the CRecord class.

Thanks...

----------------------------Life is simple, you just complicate things--------------------

Re: CRecordset problem

ovidiucucu24-Jun-06 7:16

ovidiucucu

24-Jun-06 7:16

It is not necessary to add with ClassWizard a new CRecordset-derived for each query as long as CRecordset has an Open and a Close method.

Ovidiu Cucu
Microsoft MVP - Visual C++

Re: CRecordset problem

moodsey21124-Jun-06 14:11

moodsey211

24-Jun-06 14:11

can you show me a way on updating, deleting and adding records into a database?

------------------------Life is simple, you just complicate things------------------

Re: CRecordset problem

ovidiucucu29-Jun-06 2:51

ovidiucucu

29-Jun-06 2:51

Answered HERE[^]

source of viewport [modified]

hoa_nguyen23-Jun-06 15:15

hoa_nguyen

23-Jun-06 15:15

I'm writing a programe about MFC by using viewport(win to view), but I don't know how to begin, so could you help me, could you give me some example

-- modified at 21:15 Friday 23rd June, 2006

Re: source of viewport

Hamid_RT23-Jun-06 21:12

Hamid_RT

23-Jun-06 21:12

Can you be more specific

whitesky

How to measure memory consumption?

nysubmarine23-Jun-06 10:47

nysubmarine

23-Jun-06 10:47

Hi, I have a very complex C++ object (with many class members and some of them are shared between different objects).
What is the best way to measure how much memory this object takes?

I tried the following:
before and after creating this object I call
GetProcessMemoryInfo(hProcess, &pmc, sizeof(pmc))
and then use difference in pmc.WorkingSetSize between two calls.

However it doesn't work well since WorkingSetSize increased in balks. So sometimes I get a big memory increase and other times it is zero.

Is there any system function that allow to measure exactly how much memory was allocated between two calls?

Thanks in advance for help!

PS. I develop on Windows using Visual Studio

Re: How to measure memory consumption?

Jun Du23-Jun-06 11:12

Jun Du

23-Jun-06 11:12

Try CRT debug support. Check out this CP article[^]

Best,
Jun

Link errors using std::vector

BuckBrown23-Jun-06 10:22

BuckBrown

23-Jun-06 10:22

Hi,

I am using Visual C++ 6.0 MFC and want to store objects into an array. I tried using CArray but once I got the copy contructor so it would not give me compile errors I then got LINK errors. Since so many people on the internet sugested to others trying to use CArray to use std::vector instead I decided to use std::vector, the compiler gives me couple of warnings, but I still get LINK errors.

If I do this:
std::string strData = "One";
std::vector<std::string> strVector;
strVector.push_back(strData);
std::string strData = "Two";
strVector.push_back(strData);

It compiles, links, and executes just fine.

The object that I am trying to store is,
class CInstrument : public CObject
{
public:
CInstrument();
CInstrument(const CInstrument &Instrument);
CInstrument& operator = (const CInstrument);
virtual ~CInstrument();
int m_dGPIBAddress;
}

The .cpp file implementation is:
CInstrument Instrument;
std::vector<cinstrument> Instruments;
Instrument.m_dGPIBAddress = 9;
Instruments.push_back(Instrument); // If I comment this lin out I do not get link errors

Does anyone see whats wrong here? Also, as a side note, Visual Studio has a popup that comes up after the ObjectName'.' so you can select the objects members. The popup does not come up for the Instruments'.' vector. This shouldn't be this difficult as I have already spent 12 hours trying to build an array of objects of class CInstrument.

Thanks,

Buck

Re: Link errors using std::vector

Neville Franks23-Jun-06 13:27

Neville Franks

23-Jun-06 13:27

You need to use the pre, code, < and > Formatting buttons at the bottom of the editor area otherwise we can't see your code correctly.

You also need to tell us the specific compiler and linker errors you are getting.

Neville Franks, Author of Surfulater www.surfulater.com "Save what you Surf" and ED for Windows www.getsoft.com

API needed

act_x23-Jun-06 9:57

act_x

23-Jun-06 9:57

Need to know if there is an API

1) to get the directory listing

2) To be able to search for a particular file extension

As for eg

Say i have a file i need to search for like AM01.txt in C:\temp1\temp2

I need an API to list the folders --> temp1 and then temp2

Then an API to filter *.txt files in that folder

Any ideas ?

Engineering is the effort !

Re: API needed

cje23-Jun-06 9:59

cje

23-Jun-06 9:59

have you looked at CFileFind class?

Re: API needed

David Crow23-Jun-06 10:00

David Crow

23-Jun-06 10:00

act_x wrote:
1) to get the directory listing

Use the FindFirstFile()/FindNextFile() pair.

act_x wrote:
2) To be able to search for a particular file extension

See above, just use *.txt in the pattern.

If you know the exact name of the file, and simply want to check for existence, use _access() or GetFileAttributes() instead.

"The largest fire starts but with the smallest spark." - David Crow

"Judge not by the eye but by the heart." - Native American Proverb

Re: API needed

act_x23-Jun-06 10:05

act_x

23-Jun-06 10:05

Thanks for your responses

Engineering is the effort !

Re: API needed

Hamid_RT23-Jun-06 21:08

Hamid_RT

23-Jun-06 21:08

See

<br />
(1)<br />
TCHAR lpt[260];<br />
lpt[0]='\0';<br />
strcat(lpt,"c:\\");<br />
GetCurrentDirectory(sizeof(lpt),lpt);<br />
DlgDirList(lpt,IDC_LIST2,NULL,DDL_DIRECTORY|DDL_ARCHIVE);//IDC_LIST2 is CListBox<br />
-----------------------------<br />
(2)<br />
WIN32_FIND_DATA find;<br />
HANDLE handle=FindFirstFile("*.*",&find);<br />
while(FindNextFile(handle,&find)!=0)<br />
m_List2.AddString(find.cFileName);//m_List2 is CListBox<br />
FindClose(handle); <br />

maybe it is some helpful to you

whitesky

Binary File IO

Jumpin' Jeff23-Jun-06 9:06

Jumpin' Jeff

23-Jun-06 9:06

I'm having trouble grasping Binary file I/O.

I am trying to read back a binary file that includes the following example...

char type[9]="File Type"
short MajorVersion = 1
short MinorVersion = 0

Using most methods found, I can read "File Type" but it's got garbage appended to it, so I cannot compare with a known type.

Also, I'm having trouble going beyond that. Meaning, I cannot access the version shorts.

The examples I've come across doesn't go into any depth about multiple types, or how to retrieve multiple items from a single buffer read.

Do I need to flush the buffer, and reposition my pointer?

What's the best way about getting this information out of my file?

Can someone give me a quick example of how to retrieve this data, and what method is most efficient?

Jeff

Re: Binary File IO

David Crow23-Jun-06 9:10

David Crow

23-Jun-06 9:10

Jumpin` Jeff wrote:
Using most methods found, I can read "File Type" but it's got garbage appended to it...

Exactly how are you reading the file? If you are reading nine bytes from the file, it should work.

Try this:

struct
{
    char type[9];
    short MajorVersion;
    short MinorVersion;
} myStruct;
 
FILE *pFile = fopen(..., "rb");
fread(&myStruct, sizeof(myStruct), 1, pFile);
fclose(pFile);

Depending on what you do with type, you may need room for a \0 character.

"The largest fire starts but with the smallest spark." - David Crow

"Judge not by the eye but by the heart." - Native American Proverb

Re: Binary File IO

Jumpin' Jeff23-Jun-06 9:41

Jumpin' Jeff

23-Jun-06 9:41

Thank you for such a quick responce David!

Using your example, I come up with similar to previous results....

The version shorts should have been Unsigned, My bad, but I used the following to display the extracted information....

cout << myStruct.type << "\n" << myStruct.MajorVersion<<"."<

Re: Binary File IO

David Crow23-Jun-06 9:53

David Crow

23-Jun-06 9:53

Jumpin` Jeff wrote:
File Type@ <- Actually a smiley symbol...

You will not be able to treat it as a nul-terminated string unless it actually ends with a \0 character.

"The largest fire starts but with the smallest spark." - David Crow

"Judge not by the eye but by the heart." - Native American Proverb

Re: Binary File IO [modified]

Zac Howland23-Jun-06 10:02

Zac Howland

23-Jun-06 10:02

Just a recommendation:

Instead of assuming your string is X number of characters long, write the string length first, followed by the characters in the string:

struct FileData<br />
{<br />
char* String;<br />
short MajorVersion;<br />
short MinorVersion;<br />
};<br />
<br />
// to write the file<br />
FileData data;<br />
// assuming data has already been filled in<br />
FILE pFile = fopen(..., "wb");<br />
long size = strlen(data.String);<br />
fwrite(&size, sizeof(size), 1, pFile);<br />
fwrite(data.String, size, 1, pFile);<br />
fwrite(&data.MajorVersion, sizeof(short), 1, pFile);<br />
fwrite(&data.MinorVersion, sizeof(short), 1, pFile);<br />
<br />
// to read the file<br />
FileData data1;<br />
FILE pReadFile = fopen(..., "rb");<br />
long readSize = 0;<br />
fread(&readSize, sizeof(readSize), 1, pReadFile);<br />
assert(readSize > 0);<br />
// create and initialize the new string<br />
data1.String = new char[readSize + 1];<br />
memset(data1.String, 0, readSize + 1);<br />
fread(&data1.String, readSize, 1, pReadFile);<br />
fread(&data1.MajorVersion, sizeof(short), 1, pReadFile);<br />
fread(&data1.MinorVersion, sizeof(short), 1, pReadFile);<br />

If you write the structure as a class, you can put the serialization code as a class member and have your code just call MyClass.Read/Write to make it very simple.

If you decide to become a software engineer, you are signing up to have a 1/2" piece of silicon tell you exactly how stupid you really are for 8 hours a day, 5 days a week

Zac

-- modified at 16:03 Friday 23rd June, 2006

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