1. OOP-4-Templates, ListType
CSCI 2320
Data Abstractions
Dr. Thomas E. Hicks
Computer Science Dept
Trinity University 1

2. 2 2

3. Copy Your Working Student-Interface Project Into C:\Temp
Name The Folder Template 3 3

4. C:\Temp\Templates
Download This PDF
From The Web Site

5. Compile 1

6. Copy-Paste Code From The Next Slide?  Compile Program
Use This Main Program
Copy-Paste Code From The Next Slide?  Compile Program

7. Copy/Paste Main # include "Utilities.hpp" Compile Program
# include "Student.hpp"
void MySwap (int Value1, int Value2);
int main(int argc, char * argv[]) {
int
A = 5,
B = 10;
cout << "A = " << A << " B = " << B << endl;
//MySwap (A, B);
HitCarriageRetunToContinue();
return(0); }
Compile Program

8. Insert The Following Code For MySwap
Do Not Look Ahead In The Slides!
void MySwap (int Value1, int Value2) {
int
Temp; }
30 Seconds: Finish Writing The Code That Would Match This Prototype

9. Make Those Changes Necessary To Pass By Value Pass By Value?
Some Of You Generally Code Like The Following:
void MySwap (int Value1, int Value2) {
int
Temp;
Temp = Value1;
Value1 = Value2;
Value2 = Temp; }
Make Those Changes Necessary To Pass By Value
Compile
Pass By Value?
Does Not Work

10. Solution  Pass By Reference Reference Variables Or Pointers
Prototype: void MySwap (int & Value1, int & Value2);
void MySwap (int & Value1, int & Value2) {
int
Temp;
Temp = Value1;
Value1 = Value2;
Value2 = Temp; }

11. Compile 2

12. Create Floating Point Variables AA & BB Try Passing Them To MySwap - Copy Paste Code On Next Slide

13. Copy/Paste Main int main(int argc, char * argv[]) { int A = 5, B = 10;
cout << "A = " << A << " B = " << B << endl;
MySwap (A, B);
float
AA = 5.5,
BB = 7.7;
cout << "AA = " << AA << " BB = " << BB << endl;
MySwap (AA, BB);
HitCarriageReturnToContinue();
return(0); }

14. Look At Error  No Signature For (float, float)

15. We Can Certainly Overload MySwap!

16. Infinite # Of Objects int Element bool Lumber float Squadron short int
Unit
double
Officer
long int
Desk
Student
Flower
Part
Shrub
Employee
Tree
Infinite # Of Objects
Auto
China CD
Equipment
Stamp
Soldier
Coin

17. Templates

18. Templates

19. Template Functions Begin With Something Like:
template <class T>
This Class Variable Is Called T
template <class InfoType>
Or Maybe Something Like:
This Class Variable Is Called InfoType
template <class I>
Or Maybe Something Like:
This Class Variable Is Called I

20. The Class Variable (T) Must Appear In The Parameter List
template <class T>
void MySwap (T & Value1, T & Value2);
template <class T>
void MySwap (T & Value1, T & Value2) { T
Temp;
Temp = Value1;
Value1 = Value2;
Value2 = Temp; }

21. Compile 3

22. Copy/Paste Main int main(int argc, char * argv[]) { int A = 5, B = 10;
cout << "A = " << A << " B = " << B << endl;
MySwap (A, B);
float
AA = 5.5,
BB = 7.7;
cout << "AA = " << AA << " BB = " << BB << endl;
MySwap (AA, BB);
HitCarriageReturnToContinue();
return(0); }

23. The Templated Function MySwap Works Now Works For Both int & float

24. Compile 4

25. Copy/Paste - Add This To Main
char
C = 'X',
D = '?';
cout << "C = " << C << " D = " << D << endl;
MySwap (C, D);
HitCarriageReturnToContinue();
return(0); } 25

26. Compile 5

27. Copy/Paste - Add This To Main
bool
E = true,
F = false;
cout << "E = " << E << " F = " << F << endl;
MySwap (E, F);
HitCarriageReturnToContinue();
return(0); } 27

28. Compile 6

29. Copy/Paste - Add This To Main
Student
Student1 ("Pete", 2222, MALE),
Student2 ("Sandra", 3333, FEMALE);
Student1.Display("Student1");
Student2.Display("Student2");
MySwap (Student1, Student2);
HitCarriageReturnToContinue();
return(0); }

30. Will Work For All Classes (As Long As Operator = Has Been Overloaded Properly)

31. Generic
Solutions

32. The class Variable Must Appear, At Least Once, In The Parameter List
C++ Also Supports Generics, But Templates Enable Us To Easily Create Functions That Can Be Used With Thousands Of Data Types.
template <class T> void BubbleSort(T Array[], long ActNo);
template <class InfoType> long Search(InfoType Data[], long ActNo, InfoType SoughtInfo);
The class Variable Must Appear, At Least Once, In The Parameter List

33. About Templates 33 33

34. Pattern For A "Yet To Be" Function
Templates Are Not Really Functions. They are more of a design or pattern for what shall become a function if evoked.
The Compiler Shall Generate the Necessary Variations of this Function During Run Time.
Template Functions Must be placed in .hpp files! 34

35. Function Templates facilitate code reuse!
Template Can Have Multiple Parameters
template <class InfoType, class HeaderNodeType>
class Binary Tree {
... };
An important goal of both software engineering and object-oriented programming is reuse!
Function Templates facilitate code reuse! 35

36. Templated Class ListType36 36

37. Our ListType is going to use an Array to hold the objects.
Our ListType is a container class that shall be used to house and manage a collection of objects.
Our ListType is going to use an Array to hold the objects.
The container may be Empty, Full, or somewhere in between. 37 37

38. Write The Basic Class Definition For A Templated Class, Called ListType, Whose Template Argument Is InfoType
template <class InfoType>
class ListType {
public:
private: };

39. Examples: ListType <int> IntNos;
Write The Declaration To Create An Integer Type List, Called IntNos, using our new ListType
template <class InfoType>
class ListType {
public:
private: };
Examples: ListType <int> IntNos;
ListType <char> Chars;
ListType <Student> Class;

40. Bad Design Problem: Not All Of The Lists Need The Same Capacity
Add An Array (Info) To The Private Data of ListType.
template <class InfoType>
class ListType {
public:
private: };
Bad Design Problem:
Not All Of The Lists Need The Same Capacity
InfoType
Info[10]; // Container To Store Data
ListType <int> IntNos;
ListType <char> Chars;
ListType <Student> Class; #

41. Add An ActNo (counter) To The Private Data
template <class InfoType>
class ListType {
public:
private:
InfoType
* Info; // Container To Store Data };
Better Design Problem:
Not All Of The Lists Need The Same Capacity
long
ActNo; // Actual No Items In Container

42. Add A Max (counter) To The Private Data
template <class InfoType>
class ListType {
public:
private:
InfoType
* Info; // Container To Store Data
long
ActNo; // Actual No Items In Container };
long
Max; // Capacity Of The Container

43. Add A Max (counter) To The Private Data
template <class InfoType>
class ListType {
public:
private:
InfoType
* Info; // Container To Store Data
long
ActNo; // Actual No Items In Container };
long
Max; // Capacity Of The Container
bool
Sorted; // Is Data In Info Sorted?

44. ListType (long NewMax = 10);
Write The Prototype For The Constructor ListType (long int NewMax = 10)
template <class InfoType>
class ListType {
public:
private:
InfoType
*Info; // Container To Store Data
long
Max, // Capacity Of The Container
ActNo; // Actual No Items In Container
bool
Sorted; // Data Organization };
ListType (long NewMax = 10);
Remember: the code for the class methods/functions must be placed in the .hpp file

45. Code The Constructor #1 Dynamic ListType (long NewMax = 10)
template <class InfoType>
ListType <InfoType> :: ListType (long NewMax) {
puts("Evoking Constructor ListType(NewMax)"); printf("NewMax = %ld\n\n", NewMax); }

46. Add The Following To Main
ListType <int>
Nos(5);
Compile Program

47. Keep It From Breaking Later
Code The Constructor #2 Allocate The Dynamic Memory - CHECK
template <class InfoType>
ListType <InfoType> :: ListType (long NewMax) { }
Info = new InfoType [NewMax + 1];
if (Info == NULL) { Max = 0; // If no memory, we don't want to crash
ActNo = 0; // in the future  full if ActNo <= Max Sorted = true; // won't attempt to put more in  empty
} // won't attempt to take some out  full
else
Keep It From Breaking Later

48. Don't Need To Set ActNo & Sorted TWICE?
Code The Constructor #3
template <class InfoType>
ListType <InfoType> :: ListType (long NewMax) {
Info = new InfoType [NewMax + 1];
if (Info == NULL) { Max = 0; // If no memory, we don't want to crash
ActNo = 0; // FULL  if ActNo <= Max  No Insertions Sorted = true; // EMPTY if ActNo = 0  No Withdrawals } // Sort status really does not matter
else
{ Max = NewMax;
ActNo = 0; Sorted = true }
Don't Need To Set ActNo & Sorted TWICE?

49. Code The Constructor #4 Good Solution? Not Yet!
template <class InfoType>
ListType <InfoType> :: ListType (long NewMax) {
Info = new InfoType [NewMax + 1];
ActNo = 0;
Sorted = true;
if (Info == NULL) Max = 0;
else Max = NewMax; }
Good Solution?
Not Yet!
This Semester, You Will Concentrate More On Developing "Robust Software" What If NewMax Is Negative?

50. My Constructor #5

51. My Destructor

52. Templated ListType Class Data Insertion/Append Must Start At Info[1]

53. Templated ListType Class
You May Get Sort Code From Internet
You May Have To Modify It To Start At Info[1]