1. C++
CSCE 343

2. C vs. C++ C is (more or less) a subset of C++
main() is starting point, same as C
Some important differences:
Stream insertion operator ‘<<‘ preferred method for output (as opposed to printf)
Stream extraction operator ‘>>’ preferred method for input (as opposed to scanf)
I/O has object based mechanism
Library header files do not have .h extension.
New feature: references!
Support for classes, inheritance, etc. (OO features)
Built-in string class.
Support for data-structures through the STL (Standard Template Library)

3. Namespaces Purpose: avoid conflicting names in various contexts.
Scope resolution operator ‘::’
<namespace>::<member>
std::cout
std::string
To avoid having to type the whole name (including namespace) use the using command:
using std::cout;
using std::string;

4. Basic Console Output Use the output stream cout
#include<iostream>
using std::cout;
using std::endl;
int main( int argc, char *argv[] ) {
cout << “Hello World!” << endl; }
Example code hello.cpp

5. The string class Constructing a string object: Example code string.cpp
string s1; //create empty string object
string s2(“cat”);
string s3 = “cat”;
Example code string.cpp
write code to read and print a string

6. Objects Creating an object is the same as declaring it!
The new operator is used in a slightly different context (subject for later chapters).
For now, avoid using the new operator.
Examples:
string stg; // creates the empty string
string myString(“Mickey”);
Person myPerson(“Fred”, 22);

7. Classes Separate interface from implementation
Interface goes into .h file.
Use the preprocessor wrapper to avoid multiple inclusions:
#ifndef MYCLASS_H #define MYCLASS_H … #endif
Implementation goes into .cpp file.
Include the interface file.
Any users of the class must include the interface file (.h file).
Time example Time.h, Time.cpp, TimeTest.cpp
g++ TimeTest.cpp Time.cpp

8. More Object Creation Using class Time:
Time sunset; reference to a Time object
Time arrayOfTimes[5];
array of Time objects
Time &dinnerTime = sunset;
reference to same Time object as sunset
Time *timePtr = &sunset;
pointer to a Time object

9. C++ File I/O #include <fstream> Utilizes the stream classes
std::ofstream
std::ifstream
Create file reference and open a file:
ofstream outName(“file.txt”, ios::out );
ifstream inName( “back.txt”, ios::in );
ifstream inName;
if.open(“newFile.txt”);
Check for success opening the file
if( !outName ) { … }

10. File Reading Read one character: Read one line of text into char[]:
ifstream fin( "temp.txt" );
while( fin.get(ch) )
cout << ch;
fin.close();
Read one line of text into char[]:
ifstream fin("tmp.dat");  
int MAX_LENGTH = 100;
char line[MAX_LENGTH];  
while( fin.getline(line, MAX_LENGTH) ) {
cout << "read line: " << line << endl; }
Close file
fin.close()
Example fileio.cpp and fileio2.cpp

11. More I/O Read one of text into a string Read a string from keyboard
ifstream fin(“data.txt”);
string s;
while (getline( fin, s ))
cout << s << endl;
Read a string from keyboard
getline( cin, s );
cout << "You entered " << s << endl;

12. Math Library To use math functions (like sqrt, sin, cos, etc.)
#include <cmath>
Functions are in std namespace:
std::sqrt
std::sin
std::cos

13. In Class Exercise
Create a C++ program that includes a class that represents a 2D point (x,y) coordinates.
Make x and y private.
Add getters and setters for x and y
Make two constructors, one empty, and one that takes 2 parameters (inits for x and y).
Add the following methods:
double distFromOrigin() (calculates and returns the distance that this point is from the origin)
string toString() (returns a string that represents the point, e.g. (2, 4.35) )
Write a test program that will test your class thoroughly.
Submit your code using class submission program.

14. Standard Template Library
Provides a set of templated (generic) classes for data structures.
More on templates later
We’ll focus on the map data structure.
#include <vector>
#include <map>
typedef std::vector<string> VectorType;
typedef std::map<string, Person> MapType;

15. STL Maps MapType myMap; Person p1; p1.name = “Joe Schmoe”;
p1.age = 42;
myMap[“joe”] = p1;

16. Iterators Used to traverse STL structures
MapType::iterator iter;
Typical loop (over all elements):
for( iter = myMap.begin() ; iter != myMap.end(); ++iter ) {
//process data }

17. Map Example simpleVectorExample simpleMapExample Person database
creates separate .h and .cpp files
example of overloaded stream insertion operator <<
reads person data from file people.txt

18. In-class Map / Vector
Create a C++ class to hold <movie, movie stars> information create separate .h, .cpp, and testMovie files
Data fields:
private map<key,data>
key of type string
data of type vector of strings.
public methods:
add (movieName, MovieStar)
printMovieInfo
Write a test program that creates a Movie DB with this information
Tiger : Lemmon, Matthau, Spacey
Sin City: Lewis, De Niro, Alba
Mean Girls: Fey, Lemon