CODEWITHSUNDEEP
caccess-violationcalloc
ThSorn
ThSorn

Reputation: 537

Access violation writing location 0x00000000. When increase size of array to calloc

I try to calloc 2d array and initial value of edge cell with 255, it work correctly but when I try to set dimension of array over than 12000*12000, VS2010 show Access violation writing location 0x00000000

my function of calloc 2d array

int **calloc_2d_int(int Rows, int Cols) {
      int *data = (int *)calloc(Rows*Cols,sizeof(int));
      int **array= (int **)calloc(Rows,sizeof(int*));
      for (int i=0; i<Rows; i++)
           array[i] = &(data[Cols*i]);
      return array;
}

main function

int main(int argc, char* argv[]){   

int i,j;

/*convert string to int*/
int row    = atoi(argv[1]);
int column      = atoi(argv[2]); 
int T           = atoi(argv[3]); 

int** s[2];

s[0] = calloc_2d_int(row,column);
s[1] = calloc_2d_int(row,column); 
for(i=0 ; i<row ; i++){
    s[0][i][0]        = 255;   //error at this line 
    s[1][i][0]        = 255;
    s[0][i][column-1] = 255;
    s[1][i][column-1] = 255;
}

for(i=0 ; i<column ; i++){
    s[0][0][i] = 255;
    s[1][0][i] = 255;
    s[0][row-1][i] = 255;
    s[1][row-1][i] = 255;

}
}

Thank you

Upvotes: 1

Views: 783

Answers (1)

Aracthor
Aracthor

Reputation: 5917

Access violation writing location 0x00000000

This means you are trying to write on a NULL pointer. So calloc returned NULL.

As you can read on the calloc manpage, it returns NULL on error, which can be a too big memory request.
Depending of your system, 13000 * 13000 (169 000 000) might be too big.

Always check malloc, calloc and realloc returns for an error.

Upvotes: 4

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