C / C++ / MFC Discussion Boards

Re: Read a file on click event

Nishad S15-Oct-07 21:03

Nishad S

15-Oct-07 21:03

Eranga Thennakoon wrote:
I can't read the file, which is open and write something on it before.

Can you show the exact code that is used for open and read?

Eranga Thennakoon wrote:
By the way, since I've define the readString as a CString, it is required to cast?

Since I am unaware of the parameter type, I said to make it sure that casting is proper. If you can see the data written, obviously it is not needed.

- NS -

Re: Read a file on click event

CodingLover15-Oct-07 21:14

CodingLover

15-Oct-07 21:14

For open

<br />
void CSRFToolDlg::OnBnClickedOpen()<br />
{<br />
	char* ReadFileName = "G:\\Work On\\CPP\\SRFTool\\text_file.txt" ; // File path to create<br />
<br />
	if(openFile.Open(ReadFileName, CFile::modeCreate | CFile::modeReadWrite))<br />
	{<br />
		AfxMessageBox("File creates successfully", MB_OK) ;<br />
	}<br />
	else<br />
	{<br />
		AfxMessageBox("Error in file opening", MB_OK) ;<br />
	}<br />
}<br />

For write,

<br />
void CSRFToolDlg::OnBnClickedWrite()<br />
{<br />
	GetDlgItemText(IDC_S_WRITE, readString) ;<br />
	openFile.Write((LPCTSTR)readString, readString.GetLength()) ;<br />
	AfxMessageBox("Data write to the file successfully", MB_OK) ;<br />
}<br />

For read, actually this way is not correct, because it not read the file at all. Just use the string and print.

<br />
void CSRFToolDlg::OnBnClickedRead()<br />
{<br />
	SetDlgItemText(IDC_S_READ, readString) ;<br />
}<br />

I've tried this, but not work.

<br />
void CSRFToolDlg::OnBnClickedRead()<br />
{<br />
	char tempBuffer[256] ;<br />
	UINT readText = 0;<br />
	readText = openFile.Read(tempBuffer, strlen(tempBuffer)) ;<br />
<br />
	SetDlgItemText(IDC_S_READ, readText) ;<br />
}<br />

I appreciate your help all the time...
Eranga Smile | :)

Re: Read a file on click event

Nishad S15-Oct-07 21:33

Nishad S

15-Oct-07 21:33

Eranga Thennakoon wrote:
readText = openFile.Read(tempBuffer, strlen(tempBuffer)) ;

Taking the length of tempBuffer is wrong.

And my doubt is that, before you read, are you sure that the file is opened for read?

- NS -

Re: Read a file on click event

CodingLover15-Oct-07 21:40

CodingLover

15-Oct-07 21:40

No, I'm try to find the length of the string in buffer. strlen() gives it, right? I found it on MSDN. It gives the length of CString.

Actually file is open on previous click event.

I appreciate your help all the time...
Eranga Smile | :)

Re: Read a file on click event

chandu00415-Oct-07 21:44

chandu004

15-Oct-07 21:44

but here, unless you are reading your text from file, how are you able to get its length?
any way, you can see your inbox and see my mail, to which, you can forward it.

Re: Read a file on click event

Nishad S15-Oct-07 22:44

Nishad S

15-Oct-07 22:44

Eranga Thennakoon wrote:
Actually file is open on previous click event.

After that you write the value? If so the file pointer is at the end of content, right? Then you have to reset it to initial position. In the case of CFile, you can use SeekToBegin API

- NS -

Re: Read a file on click event

CodingLover15-Oct-07 22:47

CodingLover

15-Oct-07 22:47

Yes it is true. But those comes later, isn't it? I mean need worried about those things when I use multiple lines of text. At the time I can read at least a single line pal. Cry | :((

That why I need your help.

I appreciate your help all the time...
Eranga Smile | :)

Re: Read a file on click event

Nishad S15-Oct-07 23:55

Nishad S

15-Oct-07 23:55

I am not much clear about what you said. I think you have a file having multiple lines. So when you write a string then you think that the file pointer is not at the end of the file. Am I right?

- NS -

Re: Read a file on click event

CodingLover16-Oct-07 0:09

CodingLover

16-Oct-07 0:09

Actually you no need think in that much.

Right now just write a line of text and want to read it to a edit control and display. That's it.

I appreciate your help all the time...
Eranga Smile | :)

Re: Read a file on click event

chandu00416-Oct-07 0:14

chandu004

16-Oct-07 0:14

sorry! for the delay Eranga

right now i'm called for a meeting.
i will get back by 5:30 pm

and guide u.

till then good luck!

i have some clue for u
in write button,
1.open the file in write mode,
2.write the data
3.close the file.
in read button,
1.open the file in read mode,
2.read the data
3.close the file.

Re: Read a file on click event

CodingLover16-Oct-07 0:15

CodingLover

16-Oct-07 0:15

Thanks for the tip. I'll work it on.

I appreciate your help all the time...
Eranga Smile | :)

Re: Read a file on click event

Nishad S16-Oct-07 1:14

Nishad S

16-Oct-07 1:14

Eranga Thennakoon wrote:
write a line of text and want to read it

For this, I have said to use SeekToBegin. Hope it will work.

- NS -

Re: Read a file on click event

CodingLover16-Oct-07 1:22

CodingLover

16-Oct-07 1:22

Something like this.

<br />
void CSRFToolDlg::OnBnClickedRead()<br />
{<br />
TCHAR tempBuffer[256] ;<br />
UINT readText = 0;<br />
openFile.SeekToBegin();<br />
readText = openFile.Read(tempBuffer, 256 ) ;<br />
SetDlgItemText(IDC_S_READ, tempBuffer ) ;<br />
}<br />

This code given by Naveen.R and seems it is work. But one issue is there, can't read line of text more than 256 characters.

I appreciate your help all the time...
Eranga Smile | :)

Re: Read a file on click event

Nishad S16-Oct-07 1:37

Nishad S

16-Oct-07 1:37

You are reading only 256 at the maximum.

Eranga Thennakoon wrote:
openFile.Read(tempBuffer, 256 ) ;

- NS -

Re: Read a file on click event

CodingLover16-Oct-07 1:41

CodingLover

16-Oct-07 1:41

Actually that what I'm try to change. Want to set it to the length of a line of test(a string).

I appreciate your help all the time...
Eranga Smile | :)

Re: Read a file on click event

Nishad S16-Oct-07 1:48

Nishad S

16-Oct-07 1:48

One solution can be as follows...

while( Not EOF file)
{
read the file.
add to a cstring.
}
set the cstring to edit control

- NS -

Re: Read a file on click event

chandu00416-Oct-07 1:40

chandu004

16-Oct-07 1:40

come on,
now initiate a loop, and read character by character and save them to an array.
or
i think, CFile returns you the nuymber of bytes in the file, so, read that many number of bytes. iam not sure but just try it.

Re: Read a file on click event

CodingLover16-Oct-07 1:46

CodingLover

16-Oct-07 1:46

I think it is possible using CFile::GetLength(). Wait, I'll test it now.

I appreciate your help all the time...
Eranga Smile | :)

Re: Read a file on click event

chandu00416-Oct-07 2:05

chandu004

16-Oct-07 2:05

did u get it?
hope so.

Re: Read a file on click event

chandu00415-Oct-07 21:15

chandu004

15-Oct-07 21:15

forward me your application i shall see it.

Re: Read a file on click event

CodingLover15-Oct-07 21:22

CodingLover

15-Oct-07 21:22

Sure.

But how can I attach them. I can't see your mail address. If I past on the mail-body here in the forum it can be a real mess.

I appreciate your help all the time...
Eranga Smile | :)

Re: Read a file on click event

Naveen15-Oct-07 21:12

Naveen

15-Oct-07 21:12

Eranga Thennakoon wrote:
void CSRFToolDlg::OnBnClickedRead()
{
char tempBuffer[256] ;

I think _UNICODE is defined your project so you are writing some wchar and trying to read some multi byte cahracters. try changing the following way

void CSRFToolDlg::OnBnClickedRead()<br />
{<br />
TCHAR tempBuffer[256] ;<br />
UINT readText = 0;<br />
readText = openFile.Read(tempBuffer, 256 ) ;<br />
SetDlgItemText(IDC_S_READ, readText) ;<br />
}

nave

[OpenedFileFinder]

Re: Read a file on click event

CodingLover15-Oct-07 21:18

CodingLover

15-Oct-07 21:18

I think the issue is on UINT. Is says that cannot convert parameters of SetDlgItemText() from 'UINT' to 'LPCTSTR'

I appreciate your help all the time...
Eranga Smile | :)

Re: Read a file on click event

Naveen15-Oct-07 21:27

Naveen

15-Oct-07 21:27

I just noticed you are trying to set the number of bytes returned by the read() function. If you want to set the read text change the readText with tempBuffer.

SetDlgItemText(IDC_S_READ, tempBuffer) ;

nave

[OpenedFileFinder]

Re: Read a file on click event

CodingLover15-Oct-07 21:33

CodingLover

15-Oct-07 21:33

I want to print the text which is write to the file. No need to find the number of bytes. Initially I've tried this one also. What happened is print some annoying text on the edit control. It is true, because the buffer is size of 256 which I've defined.

I appreciate your help all the time...
Eranga Smile | :)

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