1. Passing Arguments and The Big 5

2. Passing Arguments by Value
Pass to the function a copy of a variable
Advantages
Safe – the variable will not be changed in the calling context
Disadvantages
Slow – copying can be slow to copy a large objects as a variable
Arrays
Not passed by value

3. Passing Arguments by Pointer
Pass to the function a copy of the address of a variable
Advantages
Flexible – can change the value of the object
Fast – only need to copy a pointer not the whole object
Disadvantages
Unsafe – can change the value of the variable in the calling function
Complex – the variable is a pointer rather then and needs * or -> to access
Arrays
Always passed as a pointer since the name of an array is a pointer

4. Reference Variables Not pointers C++ Reference Variables
Can not be null or uninitialized
C++ Reference Variables
Declare like pointers but use & rather then *
They "refer" to another variable, but act like a variable
Must be initialized when created so can never be null
int my_int = 7;
int &my_ref = my_int;
my_ref = 8;
cout << my_int << endl;

5. Passing Arguments by Reference
Pass to the function a reference to a variable
Advantages
Flexible – can change the value of the object
Fast – only need to copy an address not the whole object
Disadvantages
Unsafe – can change the value of the variable in the calling function
Confusing – can not tell the difference at the call site
Const Ref
Safe like value but fast like a pointer

6. How hard was week 8 code review assignment?
Easy
Moderate
Challenging
Unreasonable

7. How long did week 8 assignment take?
Less than 3 hours
3 to 6 hours
6 to 9 hours
9 to 12 hours
More than 12 hours

8. Return Values Advantages Disadvantages
Safe – Will always work correctly
Disadvantages
Slow – If a large object must be copied it could be slow
With C++11 usually avoided more so with C++14

9. Return Pointers Advantages Disadvantages
Allocations – Allows returning of heap allocated objects
Disadvantages
Unsafe – returning a stack address no longer be valid after the return

10. Return Reference Advantages Disadvantages Use
Fast – always fast since only copying an address
Disadvantages
Unsafe – returning a reference to a stack variable will no longer be valid after the return
Use
Returning values from outside the function

11. Classes – No Internal "new"
Member variables
Methods
Constructor
Rule of Zero

12. Case Study: StringHolder
class StringHolder { std::string *string_; public: StringHolder() : string_(nullptr) {}; StringHolder(const char *initial_string); const char* c_str() const noexcept; void ChangeString(const char *input_string); };

13. Classes – Containers Use "new"
Rule of Zero won't work
Deep vs Shallow Copy

14. Rule of Three – Copy Assignment Operator
StringHolder& operator=(const StringHolder &source)

15. Rule of Three - Copy Constructor
StringHolder(const StringHolder &source)

16. Rule of Three - Destructor
~StringHolder()

17. Rule of Three vs Rule of Five
Rule of five (move semantics new with C++11)
Move Constructor
Move Assignment Operator
rvalue reference &&
Can bind to a temporary (rvalue)

18. Rule of Three - Move Constructor
StringHolder(StringHolder&& source)

19. Rule of Three – Move Assignment Operator
StringHolder& operator=(StringHolder&& source)