• Pointers are memory addresses used to indirectly access a variable
• The &is used to access the address
  int num =80;
  So, the address of the variable num is accessed as: &num
• A pointer is declared using an *
  int *p; // p is a pointer to an integer
  p = # // p is now a reference to num

Addresses and Pointers

• & is used as an address operator
  int i = 6;
  p = &i; /*The address of i is given to p ( p points to i) */
• The * operator is also used to access a location pointed to by an address
  *p = 5; /*Location pointed to by p is changed to a 5 (as well as i)
• A pointer is declared using the *
  int *p; / *declares a pointer to an integer - no space is allocated */
• An example
  int i=5, *p;
  cout << "hello" << I <, endl;
  cout << p << &i ;
  p = &i;
  cout << " \n"<< p<< &i;
  *p = 80;
  cout << " \n"<< i<< *p;
   
• CRASH
• Pointers can be used to point to arrays - using either of the 2 following assignment statements:
  int v[10], *vPtr, I;
  vPtr = v;
  vPtr = &v[0];
  for (I = 0; I < 10; I++)
  cout << "Element " << I << " is "
  << *(gptr + I) << endl;
• Static Array Allocation
• Declare an array of character pointers as:
  char *string[5] = {"one", "two", "three", "four", "five"};
  This produces five pointers. Where string[0] points to "one", and string[4] points to "five".
• Dynamic Array Allocation
  char *name;
  name = new char[40];
   

• Pointer arithmetic is permitted
  vPtr has the value (i.e., address) of 3000
  vPtr + 2 in conventional arithmetic would be 3002, but vPtr += 2;
  produces 3008 -gt; (3002 + 2 * 4) assuming an integer is stored in 4 bytes
• To access array element v[3]
  *(vPtr + 3) / * Parentheses needed to override precedence */
• Increments are scaled when used with pointers based on the size of what is being pointed to.
• *ptr++ Use pointer then increment
• *++ptr Increment pointer before using
• Pointer Initialization
  Initialize pointer when declared by:
  int *ptr = &number;
   

• Calling by value is the default; Use pointers to pass by reference
• Use &var_name in call
• Use *param_name in header
• Use type * in prototype

• The address of an array is the address of the 1^st element of the array
• Example
  int findmax (int *, int)
  findmax (nums, 10) nums has 10 elem
  int findmax(int *vals, int size);

• In header and prototype, the size of the first dimension may be omitted.