Do you know the syntax for each of these, used to read and write to data files?  Pointers: think of it as the memory address of the file  fopen()  fclose()  fscanf()  fprintf()

 fopen() returns a FILE pointer back to the pRead variable #include Main() { FILE *pRead; pRead = fopen(“file1.dat”, “r”); if(pRead == NULL) printf(“\nFile cannot be opened\n”); else printf(“\nFile opened for reading\n”); }

int main () { FILE * pFile; char c; pFile=fopen("alphabet.txt","w");//Open with write access for (c = 'A' ; c <= 'Z' ; c++) { putc (c, pFile);//works like fprintf } fclose (pFile); return 0; }

 Pretty basic.  Always close files when you use fopen.

 Reads a single field from a data file  “%s” will read a series of characters until a white space is found  can do fscanf(pRead, “%s\t%s”, name, hobby);

#include Main() { FILE *pRead; char name[10]; pRead = fopen(“names.dat”, “r”); if( pRead == NULL ) printf( “\nFile cannot be opened\n”); else printf(“\nContents of names.dat\n”); fscanf( pRead, “%s”, name ); while( !feof(pRead) ) { printf( “%s\n”, name ); fscanf( pRead, “%s”, name ); }

Kelly11/12/866Louisville Allen04/05/7749Atlanta Chelsea03/30/9012Charleston Can you write a program that prints out the contents of this information.dat file?

#include Main() { FILE *pRead; char name[10]; char birthdate[9]; float number; char hometown[20]; pRead = fopen(“information.dat”, “r”); if( pRead == NULL ) printf( “\nFile cannot be opened\n”); else fscanf( pRead, “%s%s%f%s”, name, birthdate, &number, hometown ); while( !feof(pRead) ) { printf( “%s \t %s \t %f \t %s\n”, name, birthdate, number, hometown ); fscanf( pRead, “%s%s%f%s”, name, birthdate, &number, hometown ); }

 The fprintf() function sends information (the arguments) according to the specified format to the file indicated by stream. fprintf() works just like printf() as far as the format goes. printf()

#include Main() { FILE *pWrite; char fName[20]; char lName [20]; float gpa; pWrite = fopen(“students.dat”,”w”); if( pWrite == NULL ) printf(“\nFile not opened\n”); else printf(“\nEnter first name, last name, and GPA separated”); printf(“\nEnter data separated by spaces:”); scanf(“%s%s%f”, fName, lName, &gpa); fprintf(pWrite, “%s \t %s \t %.2f \n”, fName, lName, gpa); fclose(pWrite); }

 Summary  Include #include directive at beginning of program  Use cin to take data from user  Use cout to display data on screen ▪ Display multiple strings and integers in the same cout statement by separating items with <<

#include using namespace std; string name = “”; int main(void) { cout<<“What is your name?”; cin>>name; cout<<endl<<“Hello ”<<name; return 0; }

#include using namespace std; int x = 25; string str2 = “This is a test”; int main( void ) { cout<<“Test”<<1<<2<<“3”; cout<<25 %7<<endl<<str2; return 0; }

Test 1234 This is a test

 How a computer stores data in its internal memory  RAM (Random-Access Memory) - temporary  ROM (Read-Only Memory) – non volatile  Store data in bytes  How you store data temporarily  Create variables based on fundamental types (bool, char, int, float)  constants: #define CONSTNAME value  sizeof()

TYPESIZEVALUES bool1 bytetrue (1) or false (0) char1 byte‘a’ to‘z’, ‘A’ to ‘Z’, ‘0’ to ‘9’, space, tab, and so on int4 bytes-2,147,483,648 to 2,147,483,647 short2 bytes-32,768 to 32,767 long4 bytes-2,147,483,648 to 2,147,483,647 float4 bytes+ - (1.2 x 10^-38 to 3.4 x 10^38) double8 bytes+- (2.3 x 10^-308 to -1.7 x 10^308)

 What do each of the following evaluate to? 1. long elves = 8; int dwarves = 8; if(elves==dwarves) //true or false? if(elves!=0) //true or false? 2. int elves = 4; int dwarves = 5; if(dwarves > (2/3)) //true or false? 3. if(0 < x < 99) //true or false? 4. if(0<= (0<1))//true or false?

 What do each of the following evaluate to? 1. long elves = 8; int dwarves = 8; if(elves==dwarves) //true if(elves!=0) //true 2. int elves = 4; int dwarves = 5; if(dwarves > (2/3)) //true 3. if(0 < x < 99) //true …TRUE (1) and FALSE (0) < if(0<= (0<1))//true

 Declare classes  Create objects  3 MAIN PRINCIPLES OF OOP  Data abstraction – hiding data members and implementation of a class behind an interface.  Encapsulation – each class represents a specific thing or concept. Multiple classes combine to produce the whole  Polymorphism-objects can be used in more than one program

 Classes are general models from which you can create objects  Classes have data members either data types or methods  Classes should contain a constructor method and a destructor method  See handout for example of a program that utilizes a class

class ClassName { memberList }; memberList can be either data member declarations or method declarations

Class Bow { //data member declarations string color; bool drawn; int numOfArrows; Bow(string aColor); //constructor ~Bow(); //destructor //methods void draw(); int fire(); };

Return_type ClassName::methodName(argumentList) { methodImplementation }

//draws the bow Void Bow::draw() { drawn = true; cout<< “The “<<color<<“bow has been drawn.”<<endl; }

 Used to create functions, classes, and variables of the same name  Ex. Namespace combat { void fire() } Namespace exploration { void fire() }

 To call a namespace combat::fire()  Say (to avoid having to put combat:: every time using namespace combat; fire()

class aClass// Base class { public: int anInt; } class aDerivedClass : public aClass//Derived class { protected: float aFloat; };

#include enum BREED { YORKIE, CAIRN, DANDIE, SHETLAND, DOBERMAN, LAB }; class Mammal{ public: Mammal(); // constructors ~Mammal();//destructor //accessors int GetAge()const; void SetAge(int); int GetWeight() const; void SetWeight(); //Other methods void Speak(); void Sleep(); protected: int itsAge; int itsWeight; }; class Dog : public Mammal { public: Dog(); // Constructors ~Dog(); // Accessors BREED GetBreed() const; void SetBreed(BREED); // Other methods // WagTail(); // BegForFood(); protected: BREED itsBreed; }; Animals MammalsReptiles HorseDog HoundTerrier YorkieCairn

 Private members are not available to derived classes. You could make itsAge and itsWeight public, but that is not desirable. You don't want other classes accessing these data members directly.  What you want is a designation that says, "Make these visible to this class and to classes that derive from this class." That designation is protected. Protected data members and functions are fully visible to derived classes, but are otherwise private.

 When do we need to override functions?  If you are a programmer example.  If we consider “Woof” of the dog as speak.  When a derived class creates a function with the same return type and signature as a member function in the base class, but with a new implementation, it is said to be overriding that method.

 #include  enum BREED { YORKIE, CAIRN, DANDIE, SHETLAND, DOBERMAN, LAB };  class Mammal {  public:  // constructors  Mammal() { cout << "Mammal constructor...\n"; }  ~Mammal() { cout << "Mammal destructor...\n"; }  //Other methods  void Speak()const { cout << "Mammal sound!\n"; }  void Sleep()const { cout << "shhh. I'm sleeping.\n"; }  protected:  int itsAge;  int itsWeight;  };  class Dog : public Mammal {  public:  // Constructors  Dog(){ cout << "Dog constructor...\n"; }  ~Dog(){ cout << "Dog destructor...\n"; }  // Other methods  void WagTail() { cout << "Tail wagging...\n"; }  void BegForFood() { cout << "Begging for food...\n"; }  void Speak()const { cout << "Woof!\n"; }  private:  BREED itsBreed;  };  int main() {  Mammal bigAnimal;  Dog fido;  bigAnimal.Speak();  fido.Speak();  getchar();  return 0;  }

 When you overload a method, you create more than one method with the same name, but with a different signature. When you override a method, you create a method in a derived class with the same name as a method in the base class and the same signature.

#include int area(int x); // square area int area(int x,int y); //triangle area float area(int x,int y, int radius); //circle area int main(){ int x=4, y=5, rad=3; cout<<"The Square area is :"<<area(x); cout<<"\nThe Triangle area is :"<<area(x,y); cout<<"\nThe Circle area is :"<<area(x,y,rad); getchar(); return 0; } int area(int x) // square area { return x*x; } int area(int x,int y ) //triangle area { return x*y; } float area(int x,int y, int radius) //circle area { return radius*radius*3.14; } Output: The Square area is: 16 The Triangle area is :20 The Circle area is: 28.26

#include class Mammal { public: void Move() const { cout << "Mammal move one step\n"; } void Move(int distance) const { cout << "Mammal move "; cout << distance <<" _steps.\n"; } protected: int itsAge; int itsWeight; }; class Dog : public Mammal { public: // You may receive a warning that you are hiding a function! void Move() const { cout << "Dog move 5 steps.\n"; } }; int main() { Mammal bigAnimal; Dog fido; bigAnimal.Move(); bigAnimal.Move(2); fido.Move(8); fido.Move(); return 0; } // Can you spot any problem/s in the last 4 lines ? Output: Mammal move one step Mammal move 2 steps. Dog move 5 steps

 To call a function you’ve overridden in a derived class you need to use virtual functions.  Example: struct Base { virtual void do_something() = 0; }; struct Derived1 : public Base { void do_something() { cout << "I'm doing something"; } }; struct Derived2 : public Base { void do_something() { cout << "I'm doing something else"; } }; int main() { Base *pBase = new Derived1; pBase->do_something();//does something delete pBase; pBase = new Derived2; pBase->do_something();//does something else delete pBase; return 0; }

Output: (1)dog (2)cat (3)horse (4)pig: 1 (1)dog (2)cat (3)horse (4)pig: 2 (1)dog (2)cat (3)horse (4)pig: 3 (1)dog (2)cat (3)horse (4)pig: 4 (1)dog (2)cat (3)horse (4)pig: 5 Woof! Meow! Winnie! Oink! Mammal speak! #include class Mammal { public: Mammal():itsAge(1) { } ~Mammal() { } virtual void Speak() const { cout << "Mammal speak!\n"; } protected: int itsAge; }; class Dog : public Mammal { public: void Speak()const { cout << "Woof!\n"; } }; class Cat : public Mammal { public: void Speak()const { cout << "Meow!\n"; } }; class Horse : public Mammal { public: void Speak()const { cout << "Winnie!\n"; } }; class Pig : public Mammal { public: void Speak()const { cout << "Oink!\n"; } }; int main() { Mammal* theArray[5]; Mammal* ptr; int choice, i; for ( i = 0; i<5; i++) { cout << "(1)dog (2)cat (3)horse (4)pig: "; cin >> choice; switch (choice) { case 1: ptr = new Dog; break; case 2: ptr = new Cat; break; case 3: ptr = new Horse; break; case 4: ptr = new Pig; break; default: ptr = new Mammal; break; } theArray[i] = ptr; } for (i=0;i<5;i++) theArray[i]->Speak(); system("pause"); return 0; }

 Only if you have to redefine a function in a Derived class that is already defined in Base Class, otherwise, it’s just extra resources when executed.

#include using namespace std; class CPolygon { protected: int width, height; public: void set_values (int a, int b) { width=a; height=b; } }; class CRectangle: public CPolygon { public: int area () { return (width * height); } }; class CTriangle: public CPolygon { public: int area () { return (width * height / 2); } }; int main () { CRectangle rect; CTriangle trgl; CPolygon * ppoly1 = &rect; CPolygon * ppoly2 = &trgl; ppoly1->set_values (4,5); ppoly2->set_values (4,5); cout << rect.area() << endl; cout << trgl.area() << endl; getchar(); return 0; }

 Used in place of a specific data type. For example, use a template to add data types together, whichever data type the user wishes (i.e. integers, floats)

#include using namespace std; template T GetMax (T a, T b) { T result; result = (a>b)? a : b; return (result); } int main () { int i=5, j=6, k; float l=10.5, m=5.6, n; k=GetMax (i,j); n=GetMax (l,m); cout << k << endl; cout << n << endl; getchar(); return 0; } Output:

int i; long l; k = GetMax (i,l); This would not be correct, since our GetMax function template expects two arguments of the same type. But if we did the following: template T GetMin (T a, U b) { return (a<b?a:b); } Then we could call the function like this: int i,j; long l; i = GetMin (j,l); Or simply: i = GetMin (j,l);

#include using namespace std; template class mypair { T a, b; public: mypair (T first, T second) { a=first; b=second;} T getmax (); }; template T mypair ::getmax () { T retval; retval = a>b? a : b; return retval; } int main () { mypair myobject (100, 75); cout << myobject.getmax(); return 0; } Output: 100

mypair myobject (115, 36); This same class would also be used to create an object to store any other type: mypair myfloats (3.0, 2.18);

#include using namespace std; // class template: template class mycontainer { T element; public: mycontainer (T arg) {element=arg;} T increase () {return ++element;} }; // class template specialization: template <> class mycontainer { char element; public: mycontainer (char arg) {element=arg;} char uppercase () { if ((element>='a')&&(element<='z')) element+='A'-'a'; return element; } }; int main () { mycontainer myint (7); mycontainer mychar ('j'); cout << myint.increase() << endl; cout << mychar.uppercase() << endl; return 0; } Output: 8 J

 Questions??  Good Luck on your Test