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.

 

[Al Bowers]

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;
}[/QUOTE]
............ 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;
}