Pointer vs. Reference

Question

What would be better practice when giving a function the original variable to work with:

unsigned long x = 4;

void func1(unsigned long& val) {
     val          


        

Answer 1

Pointers

• A pointer is a variable that holds a memory address.
• A pointer declaration consists of a base type, an *, and the variable name.
• A pointer can point to any number of variables in lifetime

• A pointer that does not currently point to a valid memory location is given the value null (Which is zero)

  BaseType* ptrBaseType;
  BaseType objBaseType;
  ptrBaseType = &objBaseType;
  

• The & is a unary operator that returns the memory address of its operand.

• Dereferencing operator (*) is used to access the value stored in the variable which pointer points to.

     int nVar = 7;
     int* ptrVar = &nVar;
     int nVar2 = *ptrVar;
  

Reference

• A reference (&) is like an alias to an existing variable.

• A reference (&) is like a constant pointer that is automatically dereferenced.

• It is usually used for function argument lists and function return values.

• A reference must be initialized when it is created.

• Once a reference is initialized to an object, it cannot be changed to refer to another object.

• You cannot have NULL references.

• A const reference can refer to a const int. It is done with a temporary variable with value of the const

  int i = 3;    //integer declaration
  int * pi = &i;    //pi points to the integer i
  int& ri = i;    //ri is refers to integer i – creation of reference and initialization