SE250:HTTB:Pointers:Pointers to pointers

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Pointers to Pointers

Named "double indirection"

"indirection" refers to indirect actions eg. an action is performed on the address to which a pointer points to. "double indirection" means indirect action on an indirect action

  • Syntax is similar

Declarations use an extra " * " eg. 

int **ptr

meaning pointer to a pointer of int, or address of pointer is stored in another pointer


Example:

First declaring 3 int objects:

  • A number 2
  • Pointer to int
  • Pointer to a pointer to int
int num = 2;
int *ptrONE;
int **ptrTWO;

Points the first pointer to the number 2 

ptrONE = #

Points the second pointer to the first pointer 

ptrTWO = &ptrONE;

This concept can be applied as many times as you want.

Example: Pointer to pointer of a pointer 

int num = 2;
int *ptrONE
int **ptrTWO
int ***ptrTHREE

ptrONE = #
ptrTWO = &ptrONE;
ptrTHREE = &ptrTWO;
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