pointers

Uninitialized pointers** :** One of the easiest ways to create a pointer bug is to try to reference the value of a pointer even though the pointer is uninitialized and does not yet point to a valid address. For example: int *p; *p = 12; The pointer p is uninitialized and points to a random location in memory when you declare it. It could be pointing into the system stack, or the global variables, or into the program’s code space, or into the operating system. [Read More]

One Dimensional Array int \*myarray = malloc(no\_of\_elements \* sizeof(int)); //Access elements as myarray$i$ 2 Dimensional Array Method1 int \*\*myarray = (int \*\*)malloc(nrows \* sizeof(int \*)); for(i = 0; i < nrows; i++) { myarray$i$ = malloc(ncolumns \* sizeof(int)); //allocating 1 D array = number of elements in column } // Access elements as myarray$i$$j$ Method 2 (Contagious Allocation) int \*\*myarray = (int \*\*)malloc(nrows \* sizeof(int \*)); myarray$0$ = malloc(nrows \* ncolumns \* sizeof(int)); for(i = 1; i < no\_of\_rows; i++) myarray$i$ = myarray$0$ + (i \* ncolumns); // Access elements as myarray$i$$j$ In either case, the elements of the dynamic array can be accessed with normal-looking array subscripts: array[i][j]. [Read More]

A pointer which points to an object that no longer exists. Its a pointer referring to an area of memory that has been deallocated. Dereferencing such a pointer usually produces garbage. Using reference counters which keep track of how many pointers are pointing to this memory location can prevent such issues. The reference counts are incremented when a new pointer starts to point to the memory location and decremented when they no longer need to point to that memory. [Read More]