C function to obtain a list of specific files in a directory

[rpingND]

I am currently working on a project that involves a large number of files (>100000) all with similar file names. ie.(1foo.0001,...,1foo.1223... and 2foo.0001 and so forth). I need a way to be able to somehow obtain a list or an array containing all of these file names. The primitive file names will be passed into the program ./myprog -i 1foo 2foo, for example. Is there a function call in c or c++ that would perform a similar function to ls, but keep returning filenames until all of the files have been processed.

Thanks

[grumpy]

There is no portable (or standard) method in C.

However, most operating systems provide functionality to do this. Under several variants of unix, "man glob" will be a useful starting point.

[itsme86]

What do you mean "returning filenames"? The shell does the filename expansion. So your program will receive all of the filenames in the second parameter passed to main().

If you do ./myprog -i * and your main() definition looked like int main(int argc, char **argv) then argc would contain the count of all of the command-line arguments (plus the name of the command itself) and argv would contain a NULL-terminated list of strings representing those arguments.

argv would look something like:
argv[0] - "./myprog"
argv[1] - "1foo.001"
argv[2] - "1foo.1223"
.
.
.
argv[argc - 1] - "2foo.001"
argv[argc] - NULL

Is that what you're looking for?

itsme@itsme:~/C$ cat cline.c
#include <stdio.h>

int main(int argc, char **argv)
{
  int i;

  printf("argc = %d\n\n", argc);

  for(i = 0;i < argc;++i)
    printf("argv[%d] - %s\n", i, argv[i]);

  return 0;
}

itsme@itsme:~/C$ ./cline foo bar blee
argc = 4

argv[0] - ./cline
argv[1] - foo
argv[2] - bar
argv[3] - blee
itsme@itsme:~/C$

And likewise:

itsme@itsme:~/C$ ls file[0-9].txt
file1.txt  file2.txt  file3.txt
itsme@itsme:~/C$ ./cline file[0-9].txt
argc = 4

argv[0] - ./cline
argv[1] - file1.txt
argv[2] - file2.txt
argv[3] - file3.txt
itsme@itsme:~/C$

[Salem]

> If you do ./myprog -i *
Bear in mind that whilst most shells have a large argument space, it isn't likely to be infinite.

When I have huge numbers of files to process, I typically do something like this

find . -name "foo*" | xargs ./myprog -i
cat filelist | xargs ./myprog -i

find is a really useful tool for finding files based on all sorts of properties.

xargs groups a long list of filenames together and invokes your program with that set of filenames. It keeps doing this until there are no more filenames.