Pointer - Array Question/Problem -Revised-

[CNewbie]

Ok this code is just like the code before, but it shows the exact problem, it will compile fine, no errors, no warnings, but when it runs it just gets a "Segmentation Fault", and outputs nothing, but if I // remark out the qsort( funtion line, it compiles fine, and outputs perfectly, albeit unsorted.
Any help, ideas, again, im using linux and gcc.

gcc -g -Wall -I../../../include test.c -o test

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <dirent.h>

char tstring[256];
char tgot[256];
char tname[256];
char tdata[50000][256];
int tfi=0;
int i=0;
DIR *pd;
struct dirent *allp;

static int scomp(const void *p1, const void *p2)
{
char *a = * (char **) p1;
char *b = * (char **) p2;
return strcasecmp(a,b);
}

int main()
{
pd = opendir (&quot;/mnt/winc/Music&quot;
if ( pd != NULL ) {
while ( (allp = readdir(pd)) ) {
sprintf(tstring,&quot;%s&quot;,allp->d_name);
strcpy(tgot,tstring);
strcpy(tname,(&tgot[0]));
sprintf(tdata[tfi],&quot;%s&quot;,tname);
tfi++;
}
}
tfi=tfi-1;
closedir(pd);
qsort(tdata, tfi, sizeof tdata[0], scomp);
i=0;
do {
printf(&quot;%s\n&quot;,tdata);
i++;
}while (i<tfi);
printf(&quot;%d\n&quot;,i);
return 0;
}

 

[Zyrenthian]

I dont think you are sorting how you mean to.

tdata, from what I can assume, will hold up to 50000 words of max length of 256.

I dont know if this is correct but with a small modification we could try

char* tdata[50000];
memset(tdata,0,sizeof(tdata));

//this would require a malloc of strlen(tname)+1 for each
//element
while ( (allp = readdir(pd)) ) 
{
      sprintf(tstring,"%s",allp->d_name);
      strcpy(tgot,tstring);
      strcpy(tname,(&tgot[0]));
      tdata[tfi] = (char*)malloc(strlen(tname)+1);
      sprintf(tdata[tfi],"%s",tname);
      tfi++;
}

// now try qsort call with
qsort(tdata,tfi,sizeof(char*),scomp);

I have not tested this but I think it should work for you. Please post if if you need more help

Matt

 

[CNewbie]

I changed it to:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <dirent.h>

char tstring[256];
char tgot[256];
char tname[256];
char* tdata[50000];

int tfi=0;
int i=0;
DIR *pd;
struct dirent *allp;

static int scomp(const void *p1, const void *p2)
{
char *a = * (char **) p1;
char *b = * (char **) p2;
return strcasecmp(a,b);
}

int main()
{

memset(tdata,0,sizeof(tdata));
pd = opendir (&quot;/mnt/winc/Music&quot;
if ( pd != NULL ) {
while ( (allp = readdir(pd)) ) {
sprintf(tstring,&quot;%s&quot;,allp->d_name);
strcpy(tgot,tstring);
strcpy(tname,(&tgot[0]));
tdata[tfi] = (char*)malloc(strlen(tname)+1);
sprintf(tdata[tfi],&quot;%s&quot;,tname);
tfi++;
}
}
tfi=tfi-1;
closedir(pd);
qsort(tdata,tfi,sizeof(char*),scomp);
i=0;
do {
printf(&quot;%s\n&quot;,tdata);
i++;
}while (i<tfi);
printf(&quot;%d of %d\n&quot;,i,tfi);
return 0;
}


and it worked!!!, thank you so much Zyrenthian, i dont understand why it looks like the array is not 2d, is there a place i can go to read up on this type of thing,

none the less, thank you.