open file error

hi all,

i 'm working on mfc program and read text file using createfile()

Code:

---


CString debug;
CString myfile;
myfile = "\\D:\\text.txt";
HANDLE hFile = CreateFile(myfile.GetBuffer(10000), GENERIC_READ | GENERIC_WRITE,
                  FILE_SHARE_READ,
                  NULL,
                  OPEN_ALWAYS,
                  FILE_ATTRIBUTE_NORMAL,
                  NULL);

myfile.ReleaseBuffer();
       

        if (INVALID_HANDLE_VALUE == hFile){// if setting/file not valid
                DWORD dw = GetLastError ();
                debug = "error";
                detail.DetailValue = debug;
        }else{detail.DetailValue = "open file succed";}

---

the file is not opened succed, and i caought the error msg: the data area passed to the system call is too small.
does anyone know this problem?
and can anyone provide succeeded way for reading file?
thanks much!

So why are you trying to use CreateFile in MFC again?

Code:

---

myfile = "\\D:\\text.txt";

---

Invalid. Remove the "\\" before "D:\\".

Code:

---

HANDLE hFile = CreateFile(myfile.GetBuffer(10000), GENERIC_READ | GENERIC_WRITE,

---

Not necessary. You only need to call GetBuffer if you need to pass a char*, but CreateFile expects a const char*, which is completely different. Just pass myfile.

Code:

---

myfile.ReleaseBuffer();

---

Again, get rid of that. It's not necessary if you don't call GetBuffer - and even if you do, it is only necessary if you modify the string buffer (which CreateFile doesn't).

but i still cannot open the file when i cancel the getbuffer method...

now i use open() instead of createfile(), and it display the error: the system cannot find the path specified.
my path is: D:\\text.txt
my file does existed in this path.
does anyone know how to solve this?

thanks!

Does the file you're trying to open actually exist? That sounds like the problem to me.

my file does existed in this path.
how's your problem? also the system can't find the file?

From reading this, I can't figure out why you're passing some ridiculously large number like 10000 to getbuffer.

Try,
after ensuring you can create / open a file at d:\

NOTE: changed the flags on CreateFile()

Code:

---

CString debug;
CString myfile;
myfile = "D:\\text.txt";
HANDLE hFile = ::CreateFile(myfile, GENERIC_READ|GENERIC_WRITE,
                  0,
                  NULL,
                  OPEN_ALWAYS,
                  FILE_ATTRIBUTE_NORMAL,
                  NULL);

        if (INVALID_HANDLE_VALUE == hFile){// if setting/file not valid
                DWORD dw = GetLastError ();
                debug = "error";
                detail.DetailValue = debug;
        }else{detail.DetailValue = "open file succed";}

---

Quote:

---

Originally Posted by novacain

Try,
after ensuring you can create / open a file at d:\

NOTE: changed the flags on CreateFile()

Code:

---

CString debug;
CString myfile;
myfile = "D:\\text.txt";
HANDLE hFile = ::CreateFile(myfile, GENERIC_READ|GENERIC_WRITE,
                  0,
                  NULL,
                  OPEN_ALWAYS,
                  FILE_ATTRIBUTE_NORMAL,
                  NULL);

        if (INVALID_HANDLE_VALUE == hFile){// if setting/file not valid
                DWORD dw = GetLastError ();
                debug = "error";
                detail.DetailValue = debug;
        }else{detail.DetailValue = "open file succed";}

---

---

thanks for reply
the :: makes no difference.

i found that when i use smartdevice dialogue based application and use createFile function, the function cannot work but it works in windows based, does anyone meet this situation and how to solve it?
thanks!

Perhaps your smart device doesn't have a D: drive.

i use emulator to run the application on window, so the d drive exists, and the file path is right...

hi all,

now i use the following code:

Code:

---


CString myfile = L"\\text.txt";
HANDLE hFile = CreateFile(myfile, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, 0,NULL);

---

but i still caught the file not found error. as in pocket pc, i put the file into my device, and for running in emulator, and put the file into the c: drive, why it still can't read the file?
thanks!

Create a file (ie with notepad.exe) called 'text.txt'

Place in the c:\ folder

Use Explorer to find the file and double click to open

[ie test the file exists and you can open it]

change

CString myfile = L"\\text.txt";

to

CString myfile = L"c:\\text.txt";

The code should now work.

If it does not, call GetLastError() as soon as you know the file failed to open. Check the error code returned in your compiler (MSVC->Tools->Error Lookup)

ie 5 == ACCESS DENIED
1006 == File not vaild

just pass the real path to the file:

Code:

---

CString myfile = L"c:\\text.txt";

---

I don't know what you're trying to do with omitting the drive letter, but it looks like the type of thing that would upset CreateFile since "\text.txt" is not a valid file name.

No, "\text.txt" is a valid file name, just as ".\text.txt" or "..\text.txt" are - they are relative filename not absolute filenames, but nevertheless, valid.

no, ".\text" is a name with . + tab + "ext.txt", which is not valid.

Quote:

---

Use any character in the current code page for a name, including Unicode characters, except characters in the range of zero (0) through 31, or any character that the file system does not allow. A name can contain characters in the extended character set (128–255). However, it cannot contain the following reserved characters:

< > : " / \ | ? *

---

It's a path. Though I don't know if CreateFile will interpret an absolute path or directory of if it will just accept a filename in the current directory.

Quote:

---

Originally Posted by Elysia

It's a path. Though I don't know if CreateFile will interpret an absolute path or directory of if it will just accept a filename in the current directory.

---

Ummmm...

No it is not.

A '\' is not a character. A '\' requires a second character in all cases.

'.\\' or '..\\' is a path

As Robwhit said, the compiler reads '\t' as a TAB, making '.\text.txt' == '. ext.txt'

I suggest you try this in your compiler and report your results.

And why don't you just use CFile and CArchive if you are using MFC in the first place??

Quote:

---

Originally Posted by novacain

Ummmm...

No it is not.

A '\' is not a character. A '\' requires a second character in all cases.

'.\\' or '..\\' is a path

As Robwhit said, the compiler reads '\t' as a TAB, making '.\text.txt' == '. ext.txt'

I suggest you try this in your compiler and report your results.

---

We're talking about real paths here, now how you type them in your compiler ;)
Obviously, in a C++ string, you'd have to type ".\\text.txt", which would translate to ".\text.txt".

Quote:

---

And why don't you just use CFile and CArchive if you are using MFC in the first place??

---

Now there's something I just can't agree less with.

Quote:

---

Originally Posted by Elysia

We're talking about real paths here, now how you type them in your compiler ;)
Obviously, in a C++ string, you'd have to type ".\\text.txt", which would translate to ".\text.txt".

---

I am/was not sure the OP understood that.....

EDIT: My previous post was directed at the OP (but reads as if directed at you. Which was not my intention, sorry.)

Alright, no harm done :)