C / C++ / MFC

28-Oct-09 20:24

Hi
How to print content of a txt file using VC++.

Thanks in advance

«_Superman_»28-Oct-09 20:59

«_Superman_»

28-Oct-09 20:59

Look at the documentation for WritePrinter[^].

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

Benjamin Bruno29-Oct-09 3:35

29-Oct-09 3:35

Hi can anybody give a sample for WritePrinter function , i am confused about getting handle to the printer ,which is obtained by using OpenPrinter function.

OpenPrinter("Printer_Name" ,&pHandle ,NULL )

From the above code ,I am confused about getting printer name, 'cos
suppose I am using more than one printers ,it is not possible to hardcode the printer name.How to get selected printer name?

thanks Smile | :)

David Crow29-Oct-09 4:19

29-Oct-09 4:19

Use GetDefaultPrinter() to get the name of the default printer. If you want the user to select a different printer, use PrintDlg().

"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown

"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

Benjamin Bruno29-Oct-09 19:26

29-Oct-09 19:26

Thanks

dxlee29-Oct-09 4:59

dxlee

29-Oct-09 4:59

The steps:

1. StartDocPrinter
2. StartPagePrinter
3. WritePrinter
4. EndPagePrinter
5. repeat 2, 3, 4 for as many pages as necessary
6. EndDocPrinter

When you are trying to print a text file directly to a printer, there will be no format information such as font, color, etc sent to the printer. The printer will use its default font to print the text file in its natural text flow. The result is not pretty.

Benjamin Bruno29-Oct-09 19:29

29-Oct-09 19:29

Hi
How to format data before printing ?

thanks

dxlee30-Oct-09 5:57

dxlee

30-Oct-09 5:57

To format text you have to print it in graphics mode. Get the printer DC and output to that DC. That way you can choose your font, size, etc. and arrange text to appropriate locations.

David Crow29-Oct-09 3:51

29-Oct-09 3:51

One way would be to use ShellExecute(hWnd, "name of txt file", "print", ...).

Benjamin Bruno29-Oct-09 20:18

Special Significance of CSingleLock and CMultiLock ?????

29-Oct-09 20:18

thanks

Hari_1628-Oct-09 20:16

Hari_16

28-Oct-09 20:16

Hi All,

Is there any spl reason to use CSingleLock and CDoubleLock objects and give the reference of a sync objects , whereas we can directly lock the resource by using CCriticalSection Lock and UnLock methods...

Please clarify me on this ..............

Thanks,
Hari

write problem in ios::in|ios::out|ios::app mode

xbottle28-Oct-09 19:05

xbottle

28-Oct-09 19:05

Hi all,
My code is like this:

#include <iostream>
#include <fstream>
using namespace std;
int main()
{
	fstream f;
	char strMsg[512];
	char buf[512];

	while(1)
	{
		f.open("c:\\1.txt", ios::in|ios::out|ios::app );
		if(f.is_open())
		{
			int i=0;
			char s[512];

			memcpy(s,"hello",512);
			i = strlen(s);
			f<<s<<std::endl;
			f.seekg(0, ios::beg);
			while(f.getline(strMsg, 512))
			{
				int i=0;
				char s[512] = "";
				memcpy(s,"hello",512);
				i = strlen(s);
				f <<s <<std::endl;
			}
			f.close();
		}

	}
}

starting, the file database.txt is empty.
The first "f<

Re: write problem in ios::in|ios::out|ios::app mode [modified]

Randor 28-Oct-09 20:09

Randor

28-Oct-09 20:09

Hi.

Some comments:

1.) I see an infinite while loop without any conditional breakage. Why do you need this?
2.) You are calling strlen on a char array without a NULL terminator. You should probably use strcpy instead of memcpy.

xbottle wrote:
but the second "f<<s<<std::endl" can="" not="" write="" database="" to="" the="" 1.txt="" file.<="" blockquote="">

Your second while loop will never be true on the second pass because you are at the end of the file after you write to the file. However if you fix this it will cause an infinite loop. I would suggest that you redesign your logic flow.

Update your code and come back for a second analysis.

Best Wishes,
-David Delaune

modified on Thursday, October 29, 2009 1:16 AM

Re: write problem in ios::in|ios::out|ios::app mode

xbottle28-Oct-09 21:20

xbottle

28-Oct-09 21:20

thanks for your answer.

1.)This is a part of my code.In my code ,it’s a thread code.So I use an infinite while loop.
2.)you let me use strcpy instead of memcpy ,I have used strcpy instead of memcpy.But I think it’s not the reason that I can’t write the file.
3.) My second while loop is really true on the second pass.
I’m not sure the reason. Before my second while loop, “f.seekg(0, ios::beg)”seek the begin of the file,maybe that’s why I’m not at the end of the file after I write to the file.

Re: write problem in ios::in|ios::out|ios::app mode

Randor 28-Oct-09 22:48

Randor

28-Oct-09 22:48

xbottle wrote:
1.)This is a part of my code.In my code ,it’s a thread code.So I use an infinite while loop.

Ok, but how do you plan to end the thread?

xbottle wrote:
2.)you let me use strcpy instead of memcpy ,I have used strcpy instead of memcpy.But I think it’s not the reason that I can’t write the file.

It could cause the application to crash. Always NULL terminate your char arrays before calling CRT functions such as strlen.

xbottle wrote:
3.) My second while loop is really true on the second pass.
I’m not sure the reason. Before my second while loop, “f.seekg(0, ios::beg)”seek the begin of the file,maybe that’s why I’m not at the end of the file after I write to the file.

Ok, I understand you now. The EOF bit has probably been set. Add this at the bottom of your second while loop:

if(f.eof())
	f.clear();

Best Wishes,
-David Delaune

Re: write problem in ios::in|ios::out|ios::app mode

xbottle30-Oct-09 0:33

xbottle

30-Oct-09 0:33

thx.
I probably found the reason.

<br />
#include <iostream><br />
#include <fstream><br />
using namespace std;<br />
int main()<br />
{	<br />
	fstream f;	<br />
	char strMsg[512];<br />
	char buf[512];<br />
	while(1)<br />
	{<br />
		f.open("c:\\1.txt", ios::in|ios::out|ios::app );<br />
		if(f.is_open())		<br />
		{			<br />
			int i=0;			<br />
			char s[512];			<br />
			memcpy(s,"hello",512);			<br />
			i = strlen(s);			<br />
			f.seekp( 0, ios_base::end );<br />
			f<<s<<std::endl;			<br />
			f.seekg(0, ios::beg);			<br />
			while(f.getline(strMsg, 512))			<br />
			{				<br />
				int i=0;				<br />
				char s[512] = "";				<br />
				memcpy(s,"hello",512);				<br />
				i = strlen(s);				<br />
				f.seekp( 0, ios_base::end );<br />
				f <<s <<std::endl;			<br />
			}			<br />
			f.close();		<br />
		}	<br />
	}<br />
}<br />

I add "f.seekp( 0, ios_base::end );" before I write the data.
The code find the end of the file,then "f <<s <<std::endl; "can write the data successful.

Re: write problem in ios::in|ios::out|ios::app mode

enhzflep28-Oct-09 22:53

enhzflep

28-Oct-09 22:53

Goodness me, what makes you think that the file pointer will get reset to the start of the file after each write?

Seriously, have a good hard look at your code - it's making my eyes sore and your logic is hurting me.

1.     f.seekg(0, ios::beg);
2.     while(f.getline(strMsg, 512))
3.     {
4.          int i=0;
5.          char s[512] = "";
6.          memcpy(s,"hello",512);
7.          i = strlen(s);
8.          f << s << std::endl;
9.     }

Quick desk-check:

1. - seek to start of file
2. - strMsg = next line of file (max of 512 chars)
3. -
4. - declare and initialize i = 0 (initialization unnecessary)
5. - s[512] = "\0" (+511 more nulls)
6. - s[512] = "hello\0" (+ 506 more unknown chars)
7. - i = 5
8. - output "hello" + "\n" to the file. File pointer points to end of file

2. - strMsg = next line of text (we're at the end of the file, so there's no more text to read)
10.

Re: write problem in ios::in|ios::out|ios::app mode

David Crow29-Oct-09 3:56

Re: write problem in ios::in|ios::out|ios::app mode

29-Oct-09 3:56

xbottle wrote:
In my code ,it’s a thread code.

At this stage of the game, you should not be doing any multithreading. That's an intermediate/advanced topic.

David Crow29-Oct-09 3:54