1. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 1 - C to C++ C++ Comments Can use the symbol // To identify single line comments

2. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 2 - C to C++ const Specifier Used to declare or specify a constant const int speed = 60; Transforms Symbolic Variable …. speed …. Symbolic constant …. speed …. Within the scope of speed speed = 85; // Illegal

3. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 3 - C to C++ Const and Pointers ObjectPointer * ptr = “Hello”; const ptr = “Hello”; ptr = “Hello”; char const ptr = “Hello”; char const char * * *

4. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 4 - C to C++ Declarations within Blocks Can declare variables within block after code segment void main () { int a; …. code int b; more code (using b) char* c; yet more code (using c) }

5. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 5 - C to C++ Declarations within a Loop for (int i = 0; i < 10; i++) { for (int i = 2; i < 15; i++) { for (int i = 4; i < 25; i++) { … } // i from inner loop } i from outer loop … for (int i = 0; i >20; i--) { }

6. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 6 - C to C++ Functions prototypes void myDataDisplay( int, char*, float)  Parameter names are not necessary  Good style suggests using names void myDataDisplay( int range, char* label, float value)

7. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 7 - C to C++ Default Parameters Trailing set or args is Initialized to Default Values The Default Values are Specified in Prototype….. void myFunction (int earth, int moon = 10, int stars = 20); Can call the function with fewer args than the declared…. printThings (10); printThings(10,20); printThings (10, 20, 30);

8. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 8 - C to C++ Overloading Function Names - Simple Polymorphism Functions can use the same names within the same scope If ………. Each function declaration and use can be distinguished by Name and Signature Signature Number and type of parameters char *s = "This is a string"; printThings (10);// Print an int printThings('a'); // Print a char printThings (s);// Print a string

9. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 9 - C to C++ Overloading Function Names - Simple Polymorphism Redeclaration If return type and signatures match…the arg names are irrelevant extern void print (int a, int b); void print (int c, int d); Erroneous Redeclaration If signatures match and return types differ char print (int a, int b); void print (int c, int d); Overloaded If signatures differ in the Number, Type, or Order of args

10. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 10 - C to C++ Reference Types - Definition  Serve as alias for an object  Must be initialized like a const syntax & operator following the type specifier in the declaration int aValue = 20;// declare and define a value int &speed = aValue;// declare and initialize a reference speed += 10; // adds 10 to aValue

11. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 11 - C to C++ Reference Types - Initialization A reference of type T Must be initialized by  Object of type T  Object that can be converted to a type T  Cannot be changed to refer to another object after initialization

12. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 12 - C to C++ Reference Types - Initialization non const Initialized only by an lvalue of the exact type Reference refers to initializer const Initialized only by an rvalue lvalue Does not need to be of the exact type Temporary object of type T created Initialized with the initializer Reference refers to the temporary

13. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 13 - C to C++ Reference Types - Initialization unsigned char mine; int d1, d2; int &a = 1024;// illegal 1024 is not an lvalue char &b = mine;//illegal not exact type int &c = d1 + d2;//illegal not an l value const int &a = 1024;// ok const char &b = mine;//ok const int &c = d1 + d2;//ok

14. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 14 - C to C++ Reference Types - Initialization Initiali zation can be eliminated only in  Argument declaration  Declaration of a function return type  Declaration of a class member  Extern specifier used

15. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 15 - C to C++ References vs. Pointers References do not support pointer like operations Cannot have …….  Pointers to references  Arrays of references Consequence of first int & v[ ] v[1] *(v+1)  Reference to reference  Reference to bit fields

16. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 16 - C to C++ void increment (int* &i) {i++;} int main( ) { int* iPtr = 0; cout << "iPtr = " << iPtr << endl;// Prints 0x00000000 increment (iPtr); cout << "iPtr = " << iPtr << endl;// Prints 0x00000002 return 0; } void increment (int* &i) {i++;} int main( ) { int* iPtr = 0; cout << "iPtr = " << iPtr << endl;// Prints 0x00000000 increment (iPtr); cout << "iPtr = " << iPtr << endl;// Prints 0x00000002 return 0; }

17. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 17 - C to C++ References as Parameters Pass by Value Function never accesses the actual args Manipulates a local copy stored on the stack Changes made to the local copies Do not affect the actual args Pass by Reference Function accesses the actual args Address of the arg is passed If arg is not to be changed use const myFunction (const int &x)

18. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 18 - C to C++ new and delete operators To manage allocation and deallocation of memory at runtime C has the functions malloc free C++ introduces the operators new delete

19. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 19 - C to C++ new and delete operators new operator Gives programmer control over storage allocation from heap at runtime Similar to malloc delete operator Gives programmer control over storage deallocation at runtime Similar to free

20. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 20 - C to C++ new and delete operators new Operator syntax new (nothrow) type [amount] returns On success pointer to newly allocated memory On failure Exception or NULL new type ( value ) Initializes the variable to value

21. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 21 - C to C++ new and delete operators int *myPtr = new int; Allocate sufficient storage to hold a single integer Pointer to storage assigned to myPtr int * myPtr = new char [ strlen (“Bon jour mes amis”) + strlen (“touts les jour”) ]; Returns a pointer to an area of memory to hold 17 + 14 characters new int(23); Returns a pointer to an int initialized to 23

22. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 22 - C to C++ new and delete operators delete operator “Destroys” object created by new…returns the memory to heap No arguments Return type void syntax delete expression delete [ ] expression In both cases expression pointer to memory allocated by new Do not use delete to free an array This operation is undefined

23. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 23 - C to C++ new and delete operators Dont’s Do not use delete to free an array Delete a single object with delete [ ] Apply delete operator to object not created by new Try to access a deleted object Try to delete a pointer to a const - that’s changing it Deuze Use delete [ ] to free any objects created with new [ ] Use delete to free any objects created with new or new ( )

24. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 24 - C to C++ int main( ) { char *stuff[ ] = {" is ", "getting ", "longer "}; char *s = new char [strlen ("My string") +1]; strcpy (s, "My string"); for (int i = 0; i< 3; i++) { s = growString(s, stuff[i]); cout << s << endl; } return 0; } char *growString(char *myString, char *aString) { char *tString = new char [strlen(myString) + strlen(aString) + 1]; strcpy (tString, myString); strcat (tString, aString); delete[ ] myString; return tString; }

25. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 25 - C to C++ Enumeration Types The name of an enumeration is a type name One can declare an instance of type T enum Bool {FALSE, TRUE}; It is not necessary to use enum qualifier in front of the type name enum Bool {NO, YES}; // NO = 0, YES = 1 enum Bool {NO, FALSE=0, YEP, TRUE=1, MAYBE}; // 00112 enum Bool {FALSE, TRUE};// 01

26. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 26 - C to C++ Enumeration Types enum Bool {FALSE, TRUE}; main() { Bool found = FALSE code if ( TRUE == found ) { … }

27. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 27 - C to C++ Scope Operator The scope operator is given by the symbol :: Operator  Used to resolve name conflicts  Access global variables :: DOES NOT access up one level

28. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 28 - C to C++ Inline Specifier Directs the compiler to perform inline substitution of function …… Similar to a macro This is only a recommendation and may be only partially implemented struct Array { …. void put (int aValue); …. }; inline void Array::put(int aValue) { …. } inline int min (int v1, int v2) { return (v1 <= v2 ? v1 : v2) } then… int minVal = min(I,I); becomes int minVal = (v1 <= v2) ? v1 : v2;

29. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 29 - C to C++ Input and Output  Similar to C…. These are not defined within the C++ language  I/O is provided as component of C++ Standard Library  Input or Output Data interpreted as stream of bytes  To use I/O functions … we must include

30. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 30 - C to C++ Input and Output IO Stream Operations Supported by input stream …… istream, ifstream, istrstream output stream …. ostream, ofstream, ostrstream IOstream class Derived from istream ostream IOS OStreamIStream IOStream

31. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 31 - C to C++ Input and Output OStream Output operation … Insertion Signified by insertion operator << Value inserted into (output) stream IStream Input operation … Extraction Signified by extraction operator >> Value extracted from (input) stream

32. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 32 - C to C++ Input and Output Predefined Stream Objects  cin istream class object connected to standard input  cout ostream class object connected to standard output  cerr ostream class object connected to standard error Provides unbuffered output  clog ostream class object connected to standard error Provides buffered output

33. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 33 - C to C++ Input and Output Output cout << stuff; Input cin >> place to put stuff; Can accept  Any builtin data types  Any complex expression that evaluates to a data type  Can be overloaded to accept user defined types  cin does not allocate space for stuff

34. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 34 - C to C++ Output Formatting Must include Precision One can alter the precision of the output precision( ) No argument returns current precision cout.precision( ); With an argument sets the precision cout.precision( int aPrecision );

35. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 35 - C to C++ Output Formatting put (char c) Output Single character cout.put(‘a’); write (char *s, int n) Output n characters from string *s char *s = “my name is”; cout.write(s, 5) gives my na

36. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 36 - C to C++ Output Formatting Change of base Use manipulators oct, dec, hex, scientific, fixed, setprecision(int n) cout << hex; Change output base to hex cout << hex << 256 prints 100 Change will remain in effect until changed again

37. Copyright 2008 Oxford Consulting, Ltd 1 October 2008 - 37 - C to C++ Input Formatting get (char c) Input single character char a; cin.get(&a);//Enter an ‘f’ cout << a;//Prints an ‘f’ read (char *s, int n) Input n bytes from stdin into memory beginning at *s getline (char *s, int n) Input upto n characters from stdin into memory beginning at *s Insert a NULL into the buffer