Pointer in c++ part2

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This slide will help you to learn Pointer assignments, Pointer arithmetic,Pointer comparisons, Pointers & arrays, Arrays of pointers, Multiple indirection

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Pointer in c++ part2

  1. 1. Author – Subhasis Nayak
  2. 2.  Pointer assignments  Pointer arithmetic  Pointer comparisons  Pointers & arrays  Arrays of pointers  Multiple indirection  Pointers to function  Dynamic allocations
  3. 3.  We know how to point a variable .  In this example I will show how to point a variable from two pointers. You must pass the vaddres1 to vAddress2.Because we passed the address of variable to vaddress1 not to vAddress2
  4. 4.  There are only two arithmetic operations that you may use on pointers: ◦ Addition ◦ Subtraction  But you can do all operation on pointer’s value as: ◦ Addition ◦ Subtraction ◦ Multiplication ◦ division
  5. 5.  There are two type of comparison of pointers ◦ In between pointer = this is the comparison held between the addresses they hold If (p1>p2) ◦ In between pointer value = here we comparing between the values they hold. If (*p1>*p2)
  6. 6.  you can direct a pointer to hold the array's address as we do for a normal variable.  As I told you array is a sequence of similar type of data type.  To hold the array's address when you direct the pointer to hold array's address it holds the first’s of that array address only.  To get the address of each element of array we have to add the exact index number of that element. how can we do that? we can do that with help of a loop or directly adding the index’s number.
  7. 7. Int array[5]; Int array[5]; Int *Parray; Int *Parray; Parray = array; Parray = &array[0];
  8. 8.  We already learned array of integers, array of floats. As like those we have one type of array i.e. Arrays of pointer.  Arrays of pointer will only hold a bunch of addresses.  These addresses may be addresses of arrays or may be addresses of different variables.  As for a integer type array compiler allocates sequence of memory to store hold addresses.
  9. 9.  When we create pointer array we have to initialize the each element to direct to a address.  The address may be a address of a variable or an array. But they must be similar data type of pointer array int var1 = 400,var2 = 600; int *arrpo[2]; arrpo[0] = &var1; arrpo[1] = &var2;
  10. 10.  We can say it point to pointer. It means we can hold the address of a pointer as we hold the address of the variable.  So when a pointer points to the address of a variable we told it indirection. When another pointer points to that pointer which points to a variable is called multiple indirection. int var; int *fPointer,**spointer; fpointer = &var; spointer = &fpointer;
  11. 11. Pointer02 Pointer01 variable • Address • Address • Value
  12. 12.  When we have a pointer to a pointer the pointer which will point to variable. We will confuse with (*), (**) and (&). So do not confuse with these.  var = gives value stored in var int var; *fpointer = gives value stored in var int *fPointer,**spointer; **spointer = gives value stored in var fpointer = &var; spointer = &fpointer; *spointer = gives address of fpointer &spointer = gives address of spointer &fpointer = gives address of fpointer &var = gives address of variable
  13. 13.  Even though a function is not a variable, it still has a physical location in memory that can be assigned to a pointer.  This address is the entry point of the function and it is the address used when the function is called.  Once a pointer points to a function, the function can be called through that pointer.  Function pointers also allow functions to be passed as arguments to other functions.

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