wifstream with getline - OD OA issue - C / C++ / MFC Discussion Boards

Re: how to recognize a original file after changing its file type?

C^hris L^osinger5-Dec-11 3:31

C^hris L^osinger

5-Dec-11 3:31

Le@rner wrote:
i am reading file properties,

from where?

image processing toolkits | batch image processing

Re: how to recognize a original file after changing its file type?

Le@rner5-Dec-11 18:45

Le@rner

5-Dec-11 18:45

using CComPtr<ishellfolder2> pShellFolder2;

Re: how to recognize a original file after changing its file type?

Albert Holguin5-Dec-11 3:20

Albert Holguin

5-Dec-11 3:20

I was thinking the same thing... those file types he named aren't even anything alike. D'Oh! | :doh:

Re: how to recognize a original file after changing its file type?

User 74293385-Dec-11 7:34

User 7429338

5-Dec-11 7:34

As Richard MacCutchan mentioned, the file content can give you a hint. Although programs are free to write whatever they want in files, many popular file types contain signatures that make them recognisable.

This[^] page contains a list with many file extensions and their signatures, including Microsoft Office files.

modified 13-Sep-18 21:01pm.

Re: how to recognize a original file after changing its file type?

Le@rner5-Dec-11 19:12

Le@rner

5-Dec-11 19:12

i chked.

my all word,excel or ppt file had D0 CF 11 E0 A1 B1 1A E1

and no hint find on 512 byte offset,

now how can i idetify the file.

Re: how to recognize a original file after changing its file type?

Richard MacCutchan5-Dec-11 22:40

Richard MacCutchan

5-Dec-11 22:40

As I said before, there is no guaranteed method to identify file types. Much of Microsoft's software uses specific patterns as identifiers within their files but the information tends to change and is generally not published.

Unrequited desire is character building. OriginalGriff
I'm sitting here giving you a standing ovation - Len Goodman

Re: how to recognize a original file after changing its file type?

Stefan_Lang6-Dec-11 0:01

Stefan_Lang

6-Dec-11 0:01

Assuming by 'interchange' you mean rename, then no.

If you mean you load it into MS Office as one type and then use 'save as' to store it in another format (e. g. load a .xls into a word document and then store the rsulting document as .doc), then you can no longer expect to be able to open it with the original program. You may be able to convert it back, but usually you'll lose a lot of extra information that way.

In any case, on Windows file name suffixes are directly tied to applications. That is why, when you try to rename a file suffix in Explorer, you will get a warning that you may no longer be able to properly open and work with that file.

Unfortunately MS never thought to force aplications to store file types right into the file itself rather than encoding it into fickle properties such as a name suffix. It makes too much sense I suppose...

wifstream with getline - OD OA issue

jkirkerx4-Dec-11 9:14

jkirkerx

4-Dec-11 9:14

I have my getline working, and I have just been schooled in file formats, such as UTF8, UTF16LE and UTF16BE. I also learned about the BOM, to figure out what kind of file I have, in case the customer modifies the original.

So I can use my wifstream to open a UTF8 SQL Text file, and read it correctly, with no 16 bit gaps. I originally used ifstream and wifstream to read a Unicode UC2 file, and got the every other character sequence, So I exported the file as UTF8, and tried again.

The getline puzzles me, and it has something to do with \n.

sqlDBFile->getline(szCommandLine, 1024);

First line reads ok
i>>?--SQL Comment --
second line is missing the first char.
REATE instead of CREATE

Here's my theory
0x000d 0x000A is end/begin mark, and getline is terminating beyond the \n.

I really need that first character, so I can detect the word GO, instead of getting O.

Re: wifstream with getline - OD OA issue

jkirkerx4-Dec-11 13:19

jkirkerx

4-Dec-11 13:19

Well I got it finally, documentation is poor, but it was there.

getline - gets the line, and keeps the /n
gets - get the line, and discards the /n

I used a do loop with a while (sqlDBFile->get()) at the end, so it was chopping off the first char of the next line.

So this is what I ended up with, but I'm not sure if I need the conv at the top

typedef std::codecvt<wchar_t, wchar_t, mbstate_t> nullcodecvt;
const nullcodecvt &conv =
std::use_facet<nullcodecvt>(std::wcin.getloc());
const std::locale from(std::wcin.getloc(), &conv);

std::wifstream *sqlDBFile = new std::wifstream;
sqlDBFile->open( szFilePath, std::ios_base::in );

// if the file stream opened
if (sqlDBFile->is_open() ) {

    if (_wcsicmp(szEncoding, L"UTF8") == 0 ) {
        sqlDBFile->seekg(3, std::ios::beg);
    }

    // Make a temp sql command buffer
    WCHAR *pzSQLCommand = new WCHAR[8192];
    wcsncpy_s(pzSQLCommand, 8192, L"-- SQL Command Buffer --\n", wcslen(L"-- SQL Command Buffer --\n") );

    // While file stream is in memory
    while (sqlDBFile->good() ) {
        while (!sqlDBFile->eof() ) {
            WCHAR szCommandLine[1024];
            for (int i = 0; i<1024; ++i) {
                szCommandLine[i] = 0xcccc;
            }

            sqlDBFile->getline(szCommandLine, 1024);

            // Check for Comment Line
            if (szCommandLine[0] == 0x002d)
                    continue;
            // Check for Unknown Line - Can't Remember this one
            if ((szCommandLine[0] == 0x0000) && (szCommandLine[1] == 0x0000))
                continue;
            // Check for Blank Line
            if ((szCommandLine[0] == 0x0000) && (szCommandLine[1] == 0xcccc))
                continue;

            if (_wcsicmp(szCommandLine, L"GO") == 0 ) {
                // if text = GO, terminate the buffer and execute the buffered command
                hr = pICommandText->SetCommandText( DBGUID_DBSQL, pzSQLCommand );
                hr = pICommandText->QueryInterface( IID_ICommandProperties, ( void ** ) &pICommandProperties );
                hr = pICommandText->Execute( NULL, IID_IRowset, NULL, &cRowsAffected, ( IUnknown ** ) &pIRowset );

                // Clear the main command buffer for next use
                for (int i = 0; i<8192; ++i) {
                    pzSQLCommand[i] = 0xcccc;
                }
            }
            else {
                // if text != GO, cat to main command buffer
                szCommandLine[wcslen(szCommandLine)] = L'\0';
                wcsncat_s(pzSQLCommand, 8196, szCommandLine, wcslen(szCommandLine) );
                continue;
            }
        }
    }

    delete pzSQLCommand;

    // close the sql command file
    sqlDBFile->close();
    sqlDBFile = NULL;
}

Error in RtlZeroMemory [SOLVED]

vishalgpt3-Dec-11 16:59

vishalgpt

3-Dec-11 16:59

RTL_QUERY_REGISTRY_TABLE query_table[2];

RtlZeroMemory(&query_table[0],sizeof(query_table));

RtlZeroMemory gives error
//Error: expression must have (pointer-to-)function type

please guide..

Answer:

Firstly sorry for late reply,

It was really a very strange error, or one can call it a bug.

I just uninstalled the visual studio express ide and re-installed it. After that RtlZeroMemory error had gone. I guess some exception or bug had occured in the ide or compiler or god knows. But it worked.

Thank you all, for sharing your precious time with me.

Regards,
Vishal