dynamic char - realloc use

[collinm]

hi

i expect to find 7 file on a folder... maybe less, maybe more...
i can surely put this number to 1... but i think doing some realloc
will be expensive...

after 7 files, i need to use realoc...

somebody could help me to use realloc?

int searchfile(char *dir, char *filename, int flength, char *ext)
{
DIR *pdir;
printf("dir: %s\n",dir);
pdir = opendir(dir);
struct dirent *pent;
char **fileArray;
int lenFile=20;
int fileCount=0;
int expectedFile=7;
fileArray = (char**) malloc( expectedFile * sizeof(char*) );
 
if (!pdir)
{
printf ("fct: searchfile - %s - Incapable d'utiliser
opendir()\n", strerror (errno));
return 1;
}
 
snprintf(tmp_mnt_dir_www, sizeof(tmp_mnt_dir_www),"%s/%s",
mnt_dir_www, "ihist.htm");
if((fp = fopen(tmp_mnt_dir_www, "w"))!=NULL)
{
while((pent = readdir(pdir)) != NULL)
{
if(strncmp(pent->d_name, filename, 5) == 0 &&
strcmp(pent->d_name + flength, ext) == 0)
{
if(expectedFile<7)
{
fileArray[fileCount] = (char*) malloc( (lenFile+1)
* sizeof(char) );
}
else
fileArray = realloc( (char
*)fileArray,(lenFile+1)*(sizeof (char);
 
fileCount++;
strcpy( fileArray[fileCount], pent->d_name );
}
}
;
fclose(fp);
}
for(i=0;i<fileCount;i++);
free(fileArray[i]);
 
free( fileArray );
closedir(pdir);
return 0;
}
 

thanks

[SM Ryan]

# fileArray = (char**) malloc( expectedFile * sizeof(char*) );

# fileArray = realloc( (char
# *)fileArray,(lenFile+1)*(sizeof (char);

Is that supposed to be sizeof(char*) instead sizeof(char)? That's a fourfold
difference on my machine.

--
SM Ryan http://www.rawbw.com/~wyrmwif/
One of the drawbacks of being a martyr is that you have to die.

[Al Bowers]

collinm wrote:

hi

i expect to find 7 file on a folder... maybe less, maybe more...
i can surely put this number to 1... but i think doing some realloc
will be expensive...

after 7 files, i need to use realoc...

somebody could help me to use realloc?

[code]
int searchfile(char *dir, char *filename, int flength, char *ext)
{
DIR *pdir;
printf("dir: %s\n",dir);
pdir = opendir(dir);
struct dirent *pent;
char **fileArray;
int lenFile=20;
int fileCount=0;
int expectedFile=7;
fileArray = (char**) malloc( expectedFile * sizeof(char*) );

if (!pdir)
{
printf ("fct: searchfile - %s - Incapable d'utiliser
opendir()\n", strerror (errno));
return 1;
}

............ code snipped *********

Ignoring the non-standard code, I see something that doesn't
look right. You have called function malloc to reserve memory
before you check pdir. This will lead to a memory leak should
pdir have value !pdir. Also, you fail to chech the return value
of malloc. The allocation could fail.

You are using dynamic allocations for a fixed size of 7 strings
of 20 chars. You might as well forego dynamic allocations, change
char **fileArray;
to char fileArray[7][20];
and you will have storage

If the insist on dynamic allocations, I would encapsulate
char **fileArray and int fileCount in a struct and write
functions that manipulates the struct.
Example,

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

typedef struct STRINGARR
{
char **String;
size_t nelem;
} STRINGARR;

/* Prototypes */
char *AddSTRINGARR(STRINGARR *p, const char *s);
void PrintSTRINGARR(STRINGARR *p, const char *s);
void FreeSTRINGARR(STRINGARR *p);

int main(void)
{
STRINGARR fnames = {NULL}; /* Emply array of file names */

/************************************************** ******
* TODO: add variables and code to search the directory *
* and for each match call function AddSTRINGARR *
* example: AddSTRINGARR(&fnames, filename); *
************************************************** ******/

/* Example */
AddSTRINGARR(&fnames,"hello.c");
AddSTRINGARR(&fnames,"GoodMorning.c");
AddSTRINGARR(&fnames,"GoodNighe.c");
PrintSTRINGARR(&fnames,"File");
FreeSTRINGARR(&fnames);
return 0;
}

char *AddSTRINGARR(STRINGARR *p, const char *s)
{
char **tmp;

if((tmp = realloc(p->String,(sizeof *tmp)*(p->nelem+1))) == NULL)
return NULL;
if((tmp[p->nelem] = malloc(strlen(s)+1)) == NULL) return NULL;
strcpy(tmp[p->nelem],s);
p->String = tmp;
return p->String[p->nelem++];
}

void PrintSTRINGARR(STRINGARR *p, const char *s)
{
size_t i;

for(i = 0; i < p->nelem; i++)
printf("%s %u. %s\n",s?s:"",i+1,p->String[i]);
return;
}

void FreeSTRINGARR(STRINGARR *p)
{
size_t i;

for(i = 0; i < p->nelem; i++) free(p->String[i]);
free(p->String);
p->String = NULL;
p->nelem = 0;
return;
}
--
Al Bowers
Tampa, Fl USA
mailto: xa******@myrapidsys.com (remove the x to send email)
http://www.geocities.com/abowers822/