1. Functions 2: Stupid Function Tricks

2. Type Coercion
C++ will try to make values fit parameters

3. Type Coercion
C++ will try to make values fit parameters

4. Overloaded Functions Overloaded Functions
same name different parameter list
int max(int x, int y) double max(double x, double y) char max(char x, char y)

5. Overloaded Functions Overloaded Functions
same name different parameter list
int foo(int x) int foo(double x) int foo(int x, int y)
Which we used determined by call:
foo(12); //must be using version 1 foo(4.5); //must be using version 2 foo(12, 13); //must be using version 3

6. Overloads
Samples:

7. Overloads
Compiler may be confused by multiple inexact matches

8. Not Overloading
Need this call to be unambiguous:

9. Not Overloading
Can not overload with different parameter names:

10. Not Overloading
Same issue:

11. Not Overloading
Can not overload with return type:

12. Default Arguments
Provide default value for parameter with assignment in list:
double round(double num, double places = 2)
Used if actual parameter not provided:
cout << round(PI, 2); cout << round(PI); //defaults to 2 places

13. Example:

14. Default Gotchas Parameters without defaults must go first No:
double round(double places = 2, double num)

15. Default Gotchas
More than one parameter can be optional: void printDate(int year, int month = 0, double day = 0);
Caller can't omit values from middle printDate(2012); //OK, month = 0, day = 0 printDate(2012, 10, 31.4); //OK printDate(2012, 10); //OK – month = 10, day = 0 printDate(2012, 31.4); //NO – bad

16. Shadowing Functions
A variable with same name as function hides it:

17. Static Variables Statically initialized variables :
Local scope
Only available in function
Global duration
Value persists between calls
Declare with static keyword

18. Static Variables I can remember things! Good use of static
One time init
Bad – everything else
Side effects = bad

19. Inline Functions
Don't bother

20. Recap Global Variables : NO Inline : NO
global const OK
Inline : NO
Static Variables : Probably Not
Default Parameters : Probably
Overloads : Yes