C / C++ / MFC

Re: how to write/read in text file with mfc project??

11-Oct-11 7:29

I'm trying to read text from a text file. I look for in msdn how to read and write in text file, and I found this:
http://msdn.microsoft.com/es-es/library/6337eske.aspx[^]

I made this funtion to read from my text file:

void CDlgResultados::loadFromFile(void)
{
	CString path= GetUserHomeDir() + _T("\\Documents\\file.txt");
	
	TCHAR	szBuffer[256]; 
	UINT    nActual = 0; 
	CFile	myFile;

	if ( myFile.Open(path, CFile::modeCreate |   
	   CFile::modeRead ) )
	{
	   myFile.Write( szBuffer, sizeof( szBuffer ) ); 
	   myFile.Flush();
	   myFile.Seek( 0, CFile::begin );
	   nActual = myFile.Read( szBuffer, sizeof( szBuffer ) ); 
	}
	m_Edit.SetWindowTextW(szBuffer);
}

But when I run the app and I press the button to read the file, I get a error that it said:
You dont have acces to this file.

Richard MacCutchan11-Oct-11 7:49

Re: how to write/read in text file with mfc project??

11-Oct-11 7:49

What is the actual value of the string in your path variable, at the time you try to create the file?

Unrequited desire is character building. OriginalGriff

antonio34311-Oct-11 7:53

Re: how to write/read in text file with mfc project??

11-Oct-11 7:53

this is the value:

C:\Users\Antonio\Documents\file.txt

Richard MacCutchan11-Oct-11 8:08

Re: how to write/read in text file with mfc project??

11-Oct-11 8:08

OK, and does that directory exist and can you create that file manually? If so then check also the suggestions from other commenters below.

Unrequited desire is character building. OriginalGriff

antonio34311-Oct-11 8:30

Re: how to write/read in text file with mfc project??

11-Oct-11 8:30

Yes, this directory exist and I made the file manually.

Maximilien11-Oct-11 7:55

Maximilien

11-Oct-11 7:55

Use the class CStdioFile to read text file.

google for example, there are many.

Watched code never compiles.

Re: how to write/read in text file with mfc project??

Chris Meech11-Oct-11 7:59

Chris Meech

11-Oct-11 7:59

Rule number 0 when working with files. Always check return codes, so you know which call is failing. Smile | :)

Best guess is that when you call to Write() to the file, you do not have permissions, since your Open() call doesn't specify that permission. Maybe the create Permission implies this, but I'm not sure. Smile | :)

Chris Meech
I am Canadian. [heard in a local bar]

In theory there is no difference between theory and practice. In practice there is. [Yogi Berra]

posting about Crystal Reports here is like discussing gay marriage on a catholic church’s website.[Nishant Sivakumar]

Re: how to write/read in text file with mfc project??

Madhu Nair11-Oct-11 8:02

Madhu Nair

11-Oct-11 8:02

antonio343 wrote:
, I get a error that it said:
You dont have acces to this file.

Open the file using

C++

CFile::modeReadWrite OR CFile::modeWrite

it seems you don't have permission to write.

Re: how to write/read in text file with mfc project??

antonio34311-Oct-11 8:19

Re: how to write/read in text file with mfc project??

11-Oct-11 8:19

I changed the mode by modeReadWrite and I get simbols like this:

<pre>쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌쳌﫸Y쳌쳌쳌쳌꣨ɷ쳌쳌偁泇¬</pre>

I also try this:

void CDlgResultados::loadFromFile(void)
{
	CString path= GetUserHomeDir() + _T("\\Documents\\file.txt");
	
	CStdioFile f1;
	f1.Open(path, CFile::modeCreate | CFile::modeRead || CFile::typeText);
	
	CStdioFile f(stdin);
	TCHAR buf[100];

	f1.ReadString(buf, 99);

	m_Edit.SetWindowTextW(buf);
}

But I get simbols.

I think that the problem is the function ReadString doesnt get the text from the file, becouse the simbol that I get are the "rubbish" which is inicializated buf

modified 11-Oct-11 14:37pm.

Richard MacCutchan11-Oct-11 8:36

Re: how to write/read in text file with mfc project??

11-Oct-11 8:36

In your original code you were writing from an uninitialised buffer, hence the garbage recorded in your file. Check the logic of your code thus:

Create the file with access for writing
Write some text either from a constant string, or from some data built by the program
Close the file
Open the file with access for reading
Read the text into a buffer
Close the file

In each case check the results of your function calls to ensure that your code has completed without error. You can also create your file manually using Notepad or similar text editor.

Unrequited desire is character building. OriginalGriff

antonio34311-Oct-11 8:51

Re: how to write/read in text file with mfc project??

11-Oct-11 8:51

Yes, I know, I try to do that, and the file is created manually.
But I dont know how to read or write in mfc.

Richard MacCutchan11-Oct-11 10:58

Re: how to write/read in text file with mfc project??

11-Oct-11 10:58

See CFile[^], and in particular the Read() and Write() functions.

Unrequited desire is character building. OriginalGriff

David Crow11-Oct-11 10:28

David Crow

11-Oct-11 10:28

antonio343 wrote:
f1.Open(path, CFile::modeCreate | CFile::modeRead || CFile::typeText);
TCHAR buf[100];
f1.ReadString(buf, 99);

You are creating an empty file and then attempting to read from it. Is that really what you want?

Also, you may want to revise your usage of the | and || operators.

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

"Show me a community that obeys the Ten Commandments and I'll show you a less crowded prison system." - Anonymous

Re: how to write/read in text file with mfc project??

antonio34311-Oct-11 14:12

Re: how to write/read in text file with mfc project??

11-Oct-11 14:12

Nooo.

I have a text file that I created manually,and I'd like to read the text from it.

I made a mistake when I write ||, but it is not the error

modified 11-Oct-11 20:20pm.

enhzflep11-Oct-11 14:32

enhzflep

11-Oct-11 14:32

`So, why are you asking for the the file to be Created?

C++

if ( myFile.Open(path, CFile::modeCreate | CFile::modeRead ) )

| is a bitwise OR, || is a logical OR

Re: how to write/read in text file with mfc project??

antonio34311-Oct-11 15:03

Re: how to write/read in text file with mfc project??

11-Oct-11 15:03

Yes you are right, I didnt know what mean this argument, if I dont put this argument, everything run rightly

enhzflep11-Oct-11 15:39

enhzflep

11-Oct-11 15:39

I continue to feel very fortunate that the vast majority of programming (that I see) is done in english.
I understand that with function/variable names in my own language I am at an advantage to those for whom they are in a different language. Thumbs Up | :thumbsup:

How to get list of COM Ports in Win32

pandit8411-Oct-11 0:57

pandit84

11-Oct-11 0:57

Is there any API which gives me list of Seial Ports available on system. I am trying to use QueryDosDevice () but its failed to provide any result .
Thanks

App_11-Oct-11 1:03

App_

11-Oct-11 1:03

Have a look there

Madhu Nair11-Oct-11 1:15

Madhu Nair

11-Oct-11 1:15

pandit84 wrote:
Is there any API which gives me list of Seial Ports available on system.

SerialPort.GetPortNames Method[^] is available as a.Net library method.

You could also try Another serial port enumerator[^] which uses a different approach to find serial ports by enumerating registry keys.

-OR-

Enumerating serial ports - W2K style [^]- Enumerating the serial ports using the SetupDi* API provided with Win2K and later

pandit84 wrote:
QueryDosDevice () but its failed to provide any result .

I have also found this support page [^] on why QueryDosDevice fails.

modified 11-Oct-11 7:31am.

Albert Holguin11-Oct-11 4:23

Albert Holguin

11-Oct-11 4:23

Good answer overall, but considering this is the "C/C++/MFC" forum, don't think pointing out things in the .Net library are applicable. +5 for the other info though...

Madhu Nair11-Oct-11 6:44

Madhu Nair

11-Oct-11 6:44

@Albert,thanks!

Albert Holguin12-Oct-11 5:16

Albert Holguin

12-Oct-11 5:16

Thank you for contributing... Smile | :)