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Introduction to C++ Programming Module 1 An Overview of C++ and OO Programming

Introduction to C++ Programming Module 1 An Overview of C++ and OO Programming. Yaodong Bi, Ph.D. Department of Computing Sciences University of Scranton (717)941-6108 bi@cs.uofs.edu. Outline. Module 1 - An Overview of C++ and OO Programming Module 2 - Classes and Operator Overloading

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Introduction to C++ Programming Module 1 An Overview of C++ and OO Programming

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  1. Introduction to C++ ProgrammingModule 1An Overview of C++ and OO Programming Yaodong Bi, Ph.D. Department of Computing Sciences University of Scranton (717)941-6108 bi@cs.uofs.edu

  2. Outline • Module 1 - An Overview of C++ and OO Programming • Module 2 - Classes and Operator Overloading • Module 3 - Inheritance and Dynamic Binding • Module 4 - Function and Class Templates • Module 5 - C++ Stream I/O and Exception Handling

  3. History • Developed by Bjarne Stroustrup at AT&T, 1986. • Originally called “C++ with classes” • C++: Enhanced version of C. • Stronger type checking • Support for data abstraction • Support for OO programming • Support for Generic programming • C++ is a superset of C. • ISO/ANSI C++ Standard, 1998

  4. // Convert miles to kilometers #include <iostream.h> const double m_to_k = 1.609; inline double convert(double mi) { return (mi *m_to_k);} int main() { double miles; cout << "Input distance in miles: "; cin >> miles; cout<<"\nDistance: "<< convert(miles) << " km." << endl; return 0; } New Comment Style // Convert ... iostream.h file C++ stream I/O Keyword const constant variable Keyword inline inline code if possible Input/output cin >> and cout << Stream manipulator endl (end line) = “\n” Example 1: A Simple C++ Program

  5. //function.cpp #include <iostream.h> void square(int*); //by pointer void sqrByRef(int&); //by reference void sqrByRef(double&); //overloaded int main() { int num = 3; square(&num); //square(int*) cout <<"by pointer (int*): " << num << endl; int rNum =4; sqrByRef(rNum); //sqrByRef(int&) cout <<"by reference (int): " << rNum << endl; double dbl = 3.5; sqrByRef(dbl); //sqrByRef(double&) cout <<"by reference (double): " << dbl << endl; return 0; } // end of main void square(int* sqr) { *sqr = (*sqr) * (*sqr); } void sqrByRef(int& sqr) { sqr = sqr * sqr; } void sqrByRef(double& y) { y = y*y; } Example 2: Reference Parameters and Function Overloading

  6. Function declaration A function must be declared before it is used. void square(int*); // prototype Pass by reference A reference is a alias of the variable. sqr in sqrByRef(int&) is an alias for rNum in main() Variable declaration A variable may be declared when it is used. int rNum; Function overloading several functions have the same name void sqrBtRef(int&); and void sqrByRef(double&); distinguished with different parameter lists. int& for the first and double& for the second Compiler finds the right one Example 2: function -- Cont’d

  7. //Class Specification // Stack.h const int maxSize = 10; class CStack { public: // public interface CStack(int sz = maxSize); // constructor void Push (int item); int Pop(); bool IsEmpty() const; bool IsFull() const; ~CStack(); // Destructor private: // private implementation int* m_Array; int m_nTop; int m_nSize; }; //Class Implmentation // stack.cpp #include <iostream.h> #include "Stack.h" CStack:: // class scope oeprator CStack(int sz) { m_Array = new int[sz]; m_nSize = sz; m_nTop = -1; } CStack::~CStack() { delete [] m_Array; } Example 3: A Stack Class

  8. // stack.cpp - continued void CStack::Push(int item) { m_Array[++m_nTop] = item; } int CStack::Pop() { return m_Array[m_nTop--]; } bool CStack::IsEmpty() const { return (m_nTop < 0); } bool CStack::IsFull() const { return (m_nTop == m_nSize - 1); } // class.cpp #include <iostream.h> #include "Stack.h" void main() { CStack stack; for ( int i = 1; i < maxSize+3; i++) { if (!stack.IsFull()) stack.Push(i*100); } while (!stack.IsEmpty()) { cout << stack.Pop() << endl; } } Example 3: Stack - cont’d

  9. Example 3: Stack - cont’d • Information Hiding • public interface and private implementation- When the private implementation is changed, the users of the class do not need to change. • Constructor: • It is executed when an object of the class is created. • Initialize the object • Destructor: • It is executed when an object of the class is destroyed. • Clean up

  10. // stackTmpl.h const int maxSize = 10; template <class T> class CStack { public: // public interface CStack(int sz = maxSize); void Push (const T& item); T Pop(); bool IsEmpty() const; bool IsFull() const; ~CStack(); private: // private implementation T* m_Array; int m_nTop; int m_nSize; }; // stack.cpp #include <iostream.h> #include "stackTmpl.h" template<class T> CStack<T>::CStack(int sz) { m_Array = new T[sz]; m_nSize = sz; m_nTop = -1; }; template<class T> void CStack<T>::Push(const T& item) { m_Array[++m_nTop] = item; }; template<class T> T CStack<T>::Pop() { return m_Array[m_nTop--]; }; Example 4: Class and Function Templates

  11. // stackTmpl.cpp -- cont’d template<class T> bool CStack<T>::IsEmpty() const { return (m_nTop < 0); }; template<class T> bool CStack<T>::IsFull() const { return (m_nTop == m_nSize - 1); }; template<class T> CStack<T>::~CStack() { delete [] m_Array; }; // template.cpp ---- Main function #include <iostream.h> #include "stackTmpl.cpp" template <class T> void Print(CStack<T>& stack); void main() { CStack<int> istack; CStack<char> cstack; for ( char i = ’A'; i < ’A'+10; i++) { if (!istack.IsFull()) istack.Push(int(i)); if (!cstack.IsFull()) cstack.Push(i); } Print(istack); Print(cstack); } template<class T> void Print(CStack<T>& stack) { while (!stack.IsEmpty()) { cout << stack.Pop() << endl; } } Example 4: Templates -- cont’d

  12. Class Templates Template definition template <class T> class CStack { public: CStack(int sz = maxSize); void Push (const T& item); ... private: T* m_Array; … }; Template instantiation // stack of integer CStack<int> iStack; // stack of double CStack<double> dStack; // stack of char CStack<char> cStack; Function Templates Template definition template<class T> void Print(CStack<T>& stack) { while (!stack.IsEmpty()) { cout << stack.Pop() << endl; } } Template instantiation // stack of integer CStack<int> iStack; // stack of double CStack<double> dStack; // stack of char CStack<char> cStack; Example 4: Templates -- cont’d

  13. CPerson Parent class CManager & CEngineer Child classes “is-a” CPerson Inherit all the operations and attributes of CPerson Print() virtual function Redefined in child classes Dynamic binding Example 5: Inheritance and Dynamic Binding

  14. //person.h #ifndef PERSON_H #define PERSON_H #include <string> using namespace std; class CPerson { public: CPerson(const string name, int age = 30); ~CPerson(); string GetName() const; int GetAge() const; void SetName(string); void SetAge(int); virtual void Print() const; private: string m_name; int m_age; }; #endif //person.cpp #include <iostream> #include "person.h" using namespace std; CPerson::CPerson(string name, int age) :m_name(name), m_age(age) { } CPerson::~CPerson() { } string CPerson::GetName() const { return m_name; } int CPerson::GetAge() const { return m_age; } void CPerson::SetName(string name) { m_name = name; } void CPerson::SetAge(int age) { m_age = age; } void CPerson::Print() const { cout << "Name:\t\t" << m_name << endl; cout << "Age:\t\t" << m_age << endl; } Example 5: Inheritance

  15. //manager.h #ifndef MANAGER_H #define MANAGER_H #include "person.h" class CManager: public CPerson { public: CManager(string name, int age=25, int mgrLevel=1); ~CManager(); int GetMgrLevel() const; void SetMgrLevel(int level); virtual void Print() const; private: int m_nMgrLevel; }; #endif //manager.cpp #include <iostream> #include "manager.h" CManager::CManager(string name, int age, int mgrLevel) :CPerson(name, age) { m_nMgrLevel = mgrLevel; } CManager::~CManager() { } int CManager::GetMgrLevel() const { return m_nMgrLevel; } void CManager::SetMgrLevel(int level) { m_nMgrLevel = level; } void CManager::Print() const { CPerson::Print(); cout << "Mngmnt Level:\t" << m_nMgrLevel << endl; } Example 5: Inheritance -- cont’d

  16. //engineer.h #ifndef ENGINEER_H #define ENGINEER_H #include "person.h" class CEngineer: public CPerson { public: CEngineer(string name, int age=25, int engType = 1); ~CEngineer(); int GetEngType() const; void SetEngType(int engType); virtual void Print() const; private: int m_nEngType; }; #endif //engineer.cpp #include <iostream> #include "engineer.h" using namespace std; CEngineer::CEngineer(string name, int age, int engType) :CPerson(name, age), m_nEngType(engType) { } CEngineer::~CEngineer() { } int CEngineer::GetEngType() const { return m_nEngType; } void CEngineer::SetEngType(int engType) { m_nEngType = engType; } void CEngineer::Print() const { CPerson::Print(); cout << "Eng Type:\t" << m_nEngType << endl; } Example 5: Inheritance -- cont’d

  17. //inheritance.cpp #include <iostream> #include "manager.h" #include "engineer.h" int main() { CManager mngr1("Bi"); //default values CManager mngr2("Brown", 25, 20); CEngineer engineer("Smith", 20, 15); // call an inherited function mngr1.SetName("Johnson"); CPerson* array[3]; array[0] = &mngr1; array[1] = &engineer; array[2] = &mngr2; // inheritance.cpp -- cont’d for (int i=0; i<3; i++) { array[i]->Print(); cout << endl; } return 0; } Example 5: Inheritance -- cont’d

  18. 1. C++ as a better C • C++ single-line comments • A common programming error is forgetting to close a c-style comment with “*/”. Using // can avoid that. • C++ stream I/O • #include <iostream.h> • cin>> for input and cout<< for output • less error prone • Declarations of variables • Don’t declare a variable until it can be initialized. • Introduce the variable into the smallest scope possible. • Inline functions • Preferinline over #defineEx: inline int square(int); • should only be used for simple, small functions. • Reduce execution time, but increase program size.

  19. 1. C++ as a better C • Reference parameters • A reference is an alias for the variable it references to. • A reference must be initialized ex: int count; int& rCount = count; rCount = 100; // count = rCount = 100 • Use const reference parameters for large objects. ex: void fooByRef(const Type& r); void fooByVal(const Type r); .... Type y; fooByRef(y); //in fooByRef, r is a reference to y and // r cannot be modified in fooByVal. fooByVal(y) //in fooByVal(), a local r is created and //initialized with the value of y. The value //of y is copied to r, which can be expensive //when r is large.

  20. 1. C++ as a better C • Theconst qualifier • Prefer const over #define - const variables are visible to debuggers. const int MaxSize = 20; const char* ptr; // a pointer pointing to a const char char* const roPtr // a const pointer to a char • The newand delete operators In C In C++ Type* ptr = malloc(sizeof(Type)); Type* ptr = new Type; free(ptr); delete ptr; Ex: ... int* ptr1 = new int(200); // *ptr = 200 int* ptr2 = new int[200]; // ptr is an array with 200 elements. delete ptr1; // delete a single object delete [] ptr2; // delete an array CStack* pStack = new CStack; // a new stack delete pStack; //delete stack - ~CStack called

  21. 1. C++ as a better C • Default arguments • provide a value for a argument int foo(int x, int y=10); ... int z = foo(20); // equal to foo(20,10); int w = foo(30, 20); // the passed overwrites the default • Default arguments must the rightmost arguments in the list. • Scope operator • When a local variable has the same name as a global variable, use :: to access the global variable. int value = 100; int main() { double value = 1.234; // global int value is not visible cout << value; // print local value (double) - 1.234; cout << ::value; // print global value (int) - 100 ...

  22. 1. C++ as a better C • Function overloading • several functions have the same name with different signatures. • The signature of a function is: • parameter list • Return type is not significant & parameter names are irrelevant. ex1: int square(int x) { return x * x; } double square (double y) {return y * y; } void main() { int integer = 7; double dbl = 7.5; cout << square(integer); // int square(int x) cout << square(dbl); // double square(double x) } ex2: 1: int foo(int, int); //okay 2: int foo(int); //okay 3: char foo(int, int); //conflict with 1 4: int foo(const int); //conflict with 2

  23. Summary of Module 1 • C++ single-line comments • C++ stream I/O • Declarations of variables • Inline functions • Reference parameters • The const qualifier • The new and delete operators • Default arguments • Scope operator • Function overloading

  24. Programming Assignments • Get Started with VC++’s IDE • Design a C++ program that prints “Hello World!”. Use VC++ 5.0 to edit, compile, and run your program. See next slide for instructions • Improve Example 3 • The push and pop operations in the example do not check whether the stack is full or empty. Type in the program and change the two operations into the following, respectively: bool Push(int item);// return true if successful, return false otherwise bool Pop(int& item);// return true if successful, return false otherwise // Note: item is passed-by-reference. • Modify the main function accordingly.

  25. Compiling C++ Programs Using VC++ • This is an extremely simple guide on how to compile a C++ program using Microsoft Visual C++ 5 • Begin Here: • 1. Start-up Microsoft Visual C++ 5.0 (Start -> Programs -> Microsoft Visual C++ 5.0 -> Microsoft Visual C++ 5.0) • 2. (File -> New) prompts new project window. Select the type of project you will be working on (e.g. Win32 Console Application). Change the directory to the desired directory and type in a unique project name • 3. You should be in the project window. Located on left side is the navigation bar. The tabs at the bottom take you to: • The Class View - Lists the classes contained in your code • File View - Lists the files containing the code • Info View - An online help section • 4. To add a file in the project, select tag "File View" in the navigation bar. Select the project name, and click new file (File -> New). • 5. Select type of file you are adding to your project. (e.g. C++ Source Code). You must type in the name of the file, but unlike UNIX, filenames can be anything here (the extension .cpp will be added automatically to the file) • 6. A new document window will appear where the code can be entered. ENTER CODE NOW! • 7. Once code input is ready, Code must be compiled (BUILD -> BUILD) or simply press F7 • 8. The debug window will appear along the bottom of the screen. It gives the current status of the compilation and linking process. Once it is done, it will report any errors in the core. • If there were errors: • 1. Any errors during compilation or linking will be displayed in the debug window at the bottom of the screen • 2. Double clicking on any error will place a pointer in the appropriate line of code in the document window. • 3. Fix errors and compile again (Build - Compile) or press <control> F7 • 4. If no errors remain, proceed to next section. Else repeat from step number one in this section • If there were no errors: • 1. Program is ready for execution. BUILD -> EXECUTE to run the program. (or press <control> F5) • 2. The program will pop-up in a console window (or other depending on your choice of project) • DONE! • This manual is downloaded from http://www.aul.fiu.edu/tech/compile.html with limited modification.

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