1. Generic Programming Techniques in C++
Generic programming allows diverse types to be used together
Without requiring inheritance relations among them
Lets native, library, and user-defined types work with each other well
Generic abstractions rely on interface polymorphism
Based on C++ templates, typedefs, and compiler’s type inference rules
Allow many combinations to be composed successfully
Impose specific rules on types’ interfaces
Today we’ll look at some examples for why this is useful
To motivate investment of effort towards a deeper understanding
To show some early techniques that you can apply right away
Subsequent lectures and studios will dig into this in more detail
We’ll look first at key generic abstractions the STL provides
Containers that can hold diverse types
Iterators that define ranges, act like built-in pointer types
Algorithms that use iterators to manipulate data in containers
Function objects that are used to extend containers and algorithms

2. STL Containers Can Hold Different Types
#include <vector>
#include <iostream>
using namespace std;
int main (int, char *[]) {
vector<char *> cstrings;
vector<int> numbers;
cstrings.push_back(“one”);
cstrings.push_back(“two”);
numbers.push_back(1);
numbers.push_back(2);
cout << cstrings[0] << endl << cstrings[1] << endl
<< numbers[0] << endl << numbers[1] << endl;
return 0; // what output is produced, and why? }

3. STL Iterators Can Act Like Pointers (Somewhat)
#include <vector>
#include <iostream>
using namespace std;
int main (int, char *[]) {
vector<char *> cstrings;
vector<int> numbers;
cstrings.push_back(“one”); cstrings.push_back(“two”);
numbers.push_back(1); numbers.push_back(2);
vector<char *>::iterator cstrings_iter =
cstrings.begin();
vector<int>::iterator numbers_iter = numbers.begin();
cout << *cstrings_iter << endl;
++cstrings_iter;
cout << *numbers_iter << endl;
++numbers_iter;
return 0; // what output is produced, and why? }

4. STL Algorithms Use Iterators to Manipulate Data
#include <vector>
#include <iostream>
#include <algorithm>
#include <iterator>
using namespace std;
int main (int, char *[]) {
vector<char *> cstrings;
vector<int> numbers;
cstrings.push_back(“one”);
cstrings.push_back(“two”);
numbers.push_back(1);
numbers.push_back(2);
copy (cstrings.begin(), cstrings.end(),
ostream_iterator<char *>(cout, “\n”));
copy (numbers.begin(), numbers.end(),
ostream_iterator<int>(cout, “\n”));
return 0; // what output is produced, and why? }

5. STL Functors Extend Algorithms (& Containers)
#include <vector>
#include <iostream>
#include <algorithm>
#include <iterator>
using namespace std;
int main (int, char *[]) {
vector<char *> cstrings;
cstrings.push_back(“one”);
cstrings.push_back(“two”);
sort (cstrings.begin(), cstrings.end(),
greater<char *>());
copy (cstrings.begin(), cstrings.end(),
ostream_iterator<char *>(cout, “\n”));
return 0; // what output is produced, and why? }