Reading general file

Question

I'm making a program that reads in a file from stdin, does something to it and sends it to stdout.

As it stands, I have a line in my program:

while((c = getchar()) != EOF){

where c is an int.

However the problem is I want to use this program on ELF executables. And it appears that there must be the byte that represents EOF for ascii files inside the executable, which results in it being truncated (correct me if I'm wrong here - this is just my hypothesis).

What is an effective general way to go about doing this? I could dig up documents on the ELF format and then just check for whatever comes at the end. That would be useful, but I think it would be better if I could still apply this program to any kind of file.

Answer 1

You'll be fine - the EOF constant doesn't contain a valid ASCII value (it's typically -1).

For example, below is an excerpt from stdio.h on my system:

/* End of file character.
   Some things throughout the library rely on this being -1.  */
#ifndef EOF
# define EOF (-1)
#endif

Answer 2

You might want to go a bit lower level and use the system functions like open(), close() and read(), this way you can do what you like with the input as it will get stored in your own buffer.