Re: dynamic char - realloc use



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: xabowers@xxxxxxxxxxxxxx (remove the x to send email)
http://www.geocities.com/abowers822/

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