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Full Discussion: ARGV help in C
Top Forums Programming ARGV help in C Post 302419826 by Learnerabc on Sunday 9th of May 2010 12:15:19 PM
Old 05-09-2010
Quote:
Originally Posted by fpmurphy
Here is a minimalist example:
Code:
#include <stdio.h>
#include <sys/types.h>
#include <dirent.h>

int
main(int argc, char *argv[])
{
   struct dirent *ent;
   DIR *dir;

   if (argc == 2) {
       if ((dir = opendir(argv[1]))) {
           while((ent = readdir(dir)) != NULL)
               puts(ent->d_name);
       } else
           fprintf(stderr, "Error opening directory %s\n", argv[1]);
   }

   return 0;
}

Thanks Sir,
If you dont mind, can you please explain how this code is working?
 

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DIRECTORY(3)						     Library Functions Manual						      DIRECTORY(3)

NAME
directory, opendir, readdir, rewinddir, closedir, telldir, seekdir - directory routines SYNOPSIS
#include <sys/types.h> #include <dirent.h> DIR *opendir(const char *dirname) struct dirent *readdir(DIR *dirp) void rewinddir(DIR *dirp) int closedir(DIR *dirp) #define _MINIX 1 #include <sys/types.h> #include <dirent.h> long telldir(DIR *dirp) int seekdir(DIR *dirp, long pos) DESCRIPTION
These routines form a system independent interface to access directories. Opendir() opens the directory dirname and returns a pointer to this open directory stream. Readdir() reads one entry from the directory as a pointer to a structure containing the field d_name, a character array containing the null-terminated name of the entry. Rewinddir() allows the directory to be read again from the beginning. Closedir() closes the directory and releases administrative data. The Minix specific functions telldir() and seekdir() allow one to get the current position in the directory file and to return there later. Seekdir() may only be called with a position returned by telldir() or 0 (rewind). These functions should not be used in portable programs. SEE ALSO
dir(5). DIAGNOSTICS
Opendir() returns a null pointer if dirname can't be opened, or if it can't allocate enough memory for the DIR structure. Readdir() returns null if there are no more directory entries or on error. Closedir() and seekdir() returns 0 on success, -1 on error. Telldir() returns -1 on error. All of them set errno appropriately. Readdir() will only set errno on error, not on end-of-dir, so you should set errno to zero before- hand, and check its value if readdir() returns null. NOTES
The return value of readdir() needs to be copied before the next operation on the same directory if it is to be saved. AUTHOR
Kees J. Bot (kjb@cs.vu.nl) DIRECTORY(3)
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