Thread: File Handling in C

How about passing all the files to merge on the command line...

Like
mymerge *.txt

>Could you elaborate a little more? I'm not sure I follow what you are saying

http://cboard.cprogramming.com/showt...threadid=44507?

>Could you elaborate a little more?
When you call the program from the command line, your shell uses wildcards to grab files with similar names. In Salem's case, the command

Code:

mymerge *.txt

Uses the * wildcard, which should grab every file in the current directory that ends with .txt. It then passes all of those files to your program instead of just one.

Originally posted by Salem
How about passing all the files to merge on the command line...

Like
mymerge *.txt

This technique only works in *nix systems. On Windows and DOS you have to use the functions for file traversal.

> On Windows and DOS you have to use the functions for file traversal.
Only if your crummy compiler doesn't include a library to expand argv[] for you.

Originally posted by Salem
> On Windows and DOS you have to use the functions for file traversal.
Only if your crummy compiler doesn't include a library to expand argv[] for you.

Didn't realize compilers did this. Which ones? And how do you pass a '*' without the expansion? I got bit on that poring to a Unix system and had to rewrite a lot of code. Yech!

In the unix world, wildcard expansion is a feature of the shell, and it expands wildcards before spawning the process with the expanded argv[]
In the MS world (DOS/Win), the shell doesn't do this, so an optional library could be linked into the startup code to achieve the same thing.

The archaic MS compilers (probably others of that era as well) usually had some optional library called setargv
http://forums.devshed.com/t90462/s.html

gcc based compilers ported to windows usually expand arguments for you, basically for transparency with the unix world from which they came.



If you didn't link with this library, then
myprog *
got argv[1] = "*"

If you did link with this library, then
myprog *
did the usual unix thing of expanding wildcards

> And how do you pass a '*' without the expansion?
In what - DOS / Win / Unix?
This is a feature of whatever shell you're using
In BASH for instance, you would do this

Code:

echo *
set -o noglob
echo *

Assuming that glob was not turned off, the first echo lists all the filename in the current directory, and the 2nd just prints *