Thread: Simple Read Write problem

Sorry guys for the terribly basic question.

I need to open, read and write information from and to a standard file.
Atm I am just trying to write the info to stderr to test if its working but to no avail.
I'm sure there's something very basic I am doing wrong but I havnt been able to find any decent example to show me.

Here is my code:

Code:

	FILE * ffp;
        /* Open Files */
	ffp = open(firstpath, O_RDONLY);
	
	/* check file opened succesfully */
	if(ffp == -1)
	{
		fprintf(stderr, "Error opening first file\n");
		exit(1);
	}

	while(read(ffp, input_buffer, BUFFER) != -1)
	{
		write(stderr, &input_buffer, sizeof(input_buffer)); 
	}

The read command is always returning -1.
This is running on a Solaris machine just so you know.

Thanks for any help.

And errno says what?

It's saying bad address

Ok I realised I wasnt mallocing any space for input_buffer but now the loop is going forever and printing nothing. Errno says bad file number.

You mean EFAULT? Then you need to check how you messed up input_buffer.

EDIT: Okay you fixed that while I was reading. Now: you can't write to stderr. You can printf to stderr, or you can write to 2.

Thanks, thats got something printing but its wrong and all over the place. To read line by line into a file how would I go about that?

Your read is correct. You should probably fix your write statement, if you are not printing what you want.

Thank you very much for your help. I have it running now. The problem was the sizeof(input_buffer). I needed to specify exactly the size which is sizeof(char) * strlen(input_buffer)