c - Using Double Pointers after memory allocated within function -

i playing double pointers in c , wondering if create function initializes table, crashes on going main when try make use of memory allocated initstringtable. believe simple fix make strtable global , believe ok, prefer not more of learning exercise me in passing table around modification i.e. should able modify strtable main or function modifytable after initstringtable. can give.

int main() {     char** strtable;      // allocates memory string table.     initstringtable(strtable);     // below lines should able copy strings newly allocated table.     // below lines cause crash however.     strcpy(strtable[0], "abcdef");      strcpy(strtable[1], "xy"); }  // allocates memory string table. function should create table // of size 10 strings each string 50 chars long. code compiles fine. void initstringtable(char** table) {    int = 0;     table = (char**)malloc(sizeof(char)*10);     for(i = 0; < 10; i++)    {       table[i] = (char*)malloc(sizeof(char)*50);    }     for(i = 0; < 10; i++)    {       memset(table[i], 0, 50);    }     strcpy(table[0], "string1"); } 

c pass value.

the value assigned table lost on returning initstringtable().

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also when allocating pointers char ask room pointers char.

so this:

... = (char**)malloc(sizeof(char)*10); 

shall @ least (assuming c):

... = malloc(sizeof(char*)*10); 

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a possible approach be:

#include <stdlib.h> #include <string.h> #include <errno.h>  int initstringtable(char *** ppptable, const size_t n, const size_t l) {    int result = 0;     if (null == ppptable)    {      result = -1;      errno = einval;    }    else    {      (*ppptable) = malloc(n * sizeof(**ppptable));      if (null == (*ppptable))      {        result = -1;      }      else      {        size_t = 0;        for(; < n; ++i)        {          (*ppptable)[i] = calloc(l, sizeof(*(*ppptable)[i]));          if (null == (*ppptable)[i])          {            result = -1;              /* failing in middle requires clean-up. */            (; > 0; --i)            {              free((*ppptable)[i-1]);            }             free(*ppptable);             (*ppptable) = null;             break;          }        }      }    }     return result;  } 

call this:

#include <stdlib.h> #include <stdio.h>  int initstringtable(char *** ppptable, const size_t n, const size_t l);  int main(void) {   int result = exit_success;   char ** strtable = null;    if ( -1 == initstringtable(&strtable, 10, 42)) //* allocate array 10 "strings" à 42 chars. */   {     perror("initstringtable() failed");     result = exit_failure;   }   else   {     strcpy(strtable[0], "abcdef");     strcpy(strtable[1], "xy");   }    return result; } 

and no, won't ridiculous "you don't wanna 3-star-programmer!" discussion.