C- Memory allocation_Method

//Allocating a 2D array using double pointer
long int **key_column;
key_column=(long int **)malloc(sizeof(int long *)*num_of_lines);
        if(key_column==NULL)
        {
            printf("\nNo host memory for the key elelments:");
            exit(0);
        }
        for(k=0;k<num_of_lines;k++)
        {
            key_column[k]=(long int *)calloc(MAX_LIMIT,sizeof(long int));
        }