How to pass ESC/POS to writefile fileapi

Question

0.00/5 (No votes)

See more:

C++

HANDLE	CreateFileResult;
BOOL    bResult;
PSP_INTERFACE_DEVICE_DETAIL_DATA dummy = GetDevices();

if (dummy != 0)
	{
	CreateFileResult = CreateFile(dummy->DevicePath, 
                                      GENERIC_WRITE | GENERIC_READ, 
                                      FILE_SHARE_WRITE | FILE_SHARE_READ, 
                                      NULL, 
                                      OPEN_ALWAYS, 
                                      FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED, 
                                      NULL);

		if (INVALID_HANDLE_VALUE == CreateFileResult) 
        {
		  std::cout << "Handle Failed " << std::endl;
		}
		else
		{
			
		  char cData1[] = { (CHAR)27, (CHAR)112 , CHAR(0), CHAR(255), CHAR(0) };
		  char cData2[] = { 0x1b, 0x70 ,0x00 ,0xFF ,0x00 };
			
			DWORD dwBytesToWrite = (DWORD)strlen(cData2);
			DWORD bytesWritten;
			OVERLAPPED osWrite = { 0,0,0 };
				
			
			WriteFile(CreateFileResult, cData2, dwBytesToWrite, &bytesWritten, &osWrite);
         }

What I have tried:

I have tried many different ways how to pass on the data (see cData1 & cData2). Can anyone help with pointing out the correct way how to pass the command? Thanks, Oliver.

Posted 2-Aug-18 9:16am

Member 12871683

Updated 2-Aug-18 11:20am

Add a Solution

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Rick York · Answer 1 · 2018-08-02T11:16:00

The problem is you are using strlen to determine the length of the data but there are nulls in the string and strlen stops counting when it finds the first one. For example, cData1 has five bytes and strlen will return 2.

You should just count the bytes and set a constant to that value (4 or 5 - I don't know if you want the last null) and use that to test your logic. When you get that working correctly then you can make it more flexible and general purpose.

Jochen Arndt · Answer 2 · 2018-08-02T11:20:00

It does not work because you are using strlen() to get the length of data to be written but your data is binary and contains NULL bytes. So you are writing only two bytes (0x1B and 0x70) which is an incomplete command. Using strlen() won't even work properly when the data does not contain a NULL byte when not appending one as string terminator.

Because you have a char array with fixed size, you can use the array size instead:

DWORD dwBytesToWrite = sizeof(cData2);

That will write all five bytes.

How to pass ESC/POS to writefile fileapi

2 solutions

Solution 1

Solution 2

Add your solution here

Preview 0