1. Template Classes

2. Templates Rule
Like function templates, class template code must be placed above main (for a single file program) or in a header file (for multiple file programs).
The function definitions for the class will either reside in the same header file, or they can be placed in a .hpp file (also non-compilable) with a #include command appropriately placed in the .h file

3. Example
.h file #ifndef SOMECLASS_H #define SOMECLASS_H // class definition template <class T> class SomeClass { ……….code here…… } #include “SomeClass.hpp” #endif
.hpp file // definition of first function template <class T> void SomeClass<T>::a_function() { ……. code here ….. } // definition of second function int SomeClass<T>::another_function() ……. code here ……….

4. Syntax Rules The class definition must be labeled as a template
Every member function must be templated

5. Stacks

6. Push 25 12

7. Push 32 25 25

8. Pop 32 25 25

9. Pop 25 12

10. Stack Example template <class T_element> class stack { private:
  T_element m_data[MAX];
int m_numElements;
public:
stack():m_numElements(0){}
stack(const stack<T_element>& source);
bool push(const T_element elm);
bool pop(T_element & elm);
bool isFull()const {return m_numElements == MAX;}
bool isEmpty()const {return m_numElements == 0;} };

11. Push template <class T_element>
bool stack<T_element>::push(const T_element elm) {
if (!isFull())
m_data[m_numElements] = elm;
m_numElements++;
return true; }
return false;

12. Push // stack.hpp template <class T_element>
bool stack<T_element>::push(const T_element elm) {
if (!isFull())
m_data[m_numElements] = elm;
m_numElements++;
return true; }
return false;

13. Pop // stack.hpp template <class T_element>
bool stack<T_element>::pop(T_element & elm) {
 if (!isEmpty())
elm = m_data[m_numElements-1];
m_numElements--;
return true; }
return false;

14. Pop // stack.hpp template <class T_element>
bool stack<T_element>::pop(T_element & elm) {
 if (!isEmpty())
elm = m_data[m_numElements-1];
m_numElements--;
return true; }
return false;

15. Copy Constructor template <class T_element>
stack<T_element>::stack(const stack<T_element>& source) {
    m_numElements = source.m_numElements;
    for (int i=0; i < m_numElements; i++)
        m_data[i] = source.m_data[i]; }

16. Copy Constructor template <class T_element>
stack<T_element>::stack(const stack<T_element>& source) {
    m_numElements = source.m_numElements;
    for (int i=0; i < m_numElements; i++)
        m_data[i] = source.m_data[i]; }

17. Copy Constructor template <class T_element>
stack<T_element>::stack(const stack<T_element>& source) {
    m_numElements = source.m_numElements;
    for (int i=0; i < m_numElements; i++)
        m_data[i] = source.m_data[i]; }

18. Copy Constructor template <class T_element>
stack<T_element>::stack(const stack<T_element>& source) {
    m_numElements = source.m_numElements;
    for (int i=0; i < m_numElements; i++)
        m_data[i] = source.m_data[i]; }

19. Example stack<int> ant_hill; int a_value; ant_hill.pop(a_value);
ant_hill.push(5);
ant_hill.push(6);

20. Example stack<int> ant_hill; int a_value; ant_hill.pop(a_value);
ant_hill.push(5);
ant_hill.push(6);
[0]
[1]
[2]
[3]
[4] ? ? ? ? ?

21. Example stack<int> ant_hill; int a_value; ant_hill.pop(a_value);
ant_hill.push(5);
ant_hill.push(6);
[0]
[1]
[2]
[3]
[4]
a_value ? ? ? ? ? ?

22. Example stack<int> ant_hill; int a_value; ant_hill.pop(a_value);
ant_hill.push(5);
ant_hill.push(6);
[0]
[1]
[2]
[3]
[4]
a_value
??? ? ? ? ? ?

23. Example stack<int> ant_hill; int a_value; ant_hill.pop(a_value);
ant_hill.push(5);
ant_hill.push(6);
[0]
[1]
[2]
[3]
[4]
a_value ? 5 ? ? ? ?

24. Example stack<int> ant_hill; int a_value; ant_hill.pop(a_value);
ant_hill.push(5);
ant_hill.push(6);
[0]
[1]
[2]
[3]
[4]
a_value ? 5 6 ? ? ?

25. Example stack<int> ant_hill; int a_value; ant_hill.pop(a_value);
ant_hill.push(5);
ant_hill.push(6);
[0]
[1]
[2]
[3]
[4]
a_value 6 5 ? ? ? ?

26. Example 2
class elephant { private: float m_wt; string m_name; public: elephant(string name, float wt); void do_something(); }; stack<elephant> pack_o_derms;

27. Example 2
template <class T_animal> class farm { public: farm():m_herdSize(0){} private: T_animal my_herd[MAX]; int m_herdSize; }; farm<elephant> large_animal_ranch;

28. End of Session