On Mon, Jun 19, 2006 at 11:59:07PM +0100, Yianni wrote:
[...]
OK, I'll bite. Here is a little program implementing a dynamic array
with the help of realloc. Basically it defines a data type (as a pointer
to a struct holding the max number of slots allocated, the number of
actually used slots and a pointer to an (initially empty) array of
character pointers, which gets resized as needed.
Three functions comprise the interface to this thing:
filelist_new() returns a new (empty) filelist thingie
filelist_add(fl, name) adds a name to the filelist
filelist_delete() frees all allocated space.
Of course, for more fancy stuff, the rich data types offered by glib are
worth a look. Sometimes, a GList or a GSList are just more flexible
(albeit with more overhead).
Here it goes (but it's getting quite off-topic):
(WARNING: very lightly tested. Error recovery next to non-existent. Use
at your own risk. Yadda, yadda, yadda).
+------------------------------------------------------------
| /* filelist.c */
| #include <stdio.h>
| #include <stdlib.h>
| #include <string.h>
| #include <sys/types.h>
| #include <dirent.h>
|
| typedef struct {
| int nnames;
| int maxnames;
| char **names;
| } _filelist;
|
| typedef _filelist* filelist;
|
| filelist filelist_new()
| {
| filelist fl = malloc(sizeof(_filelist));
| fl->nnames = fl->maxnames = 0;
| fl->names = NULL;
| return fl;
| }
|
| void filelist_add(filelist fl, char *name)
| {
| void *blub;
| if(fl->nnames >= fl->maxnames) { /* no room: grow */
| /* adjust growth and start size to your tastes */
| int newmax = fl->maxnames;
| if(newmax > 5) newmax *= 1.2; /* 20 percent growth */
| else newmax = 16; /* arbitrary start size, should be >= 5 */
| fl->names = realloc(fl->names, newmax*sizeof(char *));
| fl->maxnames = newmax;
| }
| fl->names[fl->nnames++] = strdup(name);
| }
|
| void filelist_delete(filelist fl)
| {
| int i;
| for(i=0; i<fl->nnames; i++) free(fl->names[i]); /* free strings */
| free(fl->names); /* free array of pointers */
| free(fl); /* free struct */
| }
|
| int main(int argc, char *argv[])
| {
| DIR *d;
| struct dirent *e;
| filelist fl;
| int i;
|
| if( (d = opendir("/home/tomas")) == NULL ) {
| fprintf(stderr, "AAARGH\n");
| exit(1);
| }
|
| fl = filelist_new();
|
| while( (e = readdir(d)) != NULL ) {
| filelist_add(fl, e->d_name);
| }
|
| closedir(d);
|
| for(i=0; i<fl->nnames; i++) {
| printf("%s\n", fl->names[i]);
| }
| return 0;
| }
+------------------------------------------------------------
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