 data_type array_name [number-of-elements];  Two Dimensional Array array_type array_name [number_of_ROWS][number_of_COLUMNS];

 type* pointer_name;  ex. int my_int; int* my_int_pointer = &my_int; Assigns the address of my_int to the pointer

 Copying strings from one to another  char* strcpy(char* p, const char* q);  char s[6]; strcpy(s, “Hello”);  To combine strings  char* strcat(char* p, const char* q);  char s[12] = “Hello” strcat(s, “World”);

 To copy n characters from q to the of p.  char* strncpy(char* p, const char* q, int n);  char s [7] = “Say “; char t[] = “Hi”; strncpy (s, t, 2)

 Can you write a program using C++ that uses a FOR loop to initialize a 2D array that looks like the following {0,5,10,15}{0,2,4,6}

#include using namespace std; int main(){ int array[2][4],, row, column; for(row=0;row<2;row++) for(column=0;column<4;column++){ if(row==0) array[row][column]=column*5; else if(row==1) array[row][column]=column*2; } for(row=0; row<2; row++){ for(column =0; column <4; column ++) cout<<array[row][column]<<" "; cout<<endl; } system("pause"); return 0; }

 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; }

Please enter how long your name is: 21 Please enter your name: Nawaf Hello Nawaf Please enter how long your name is: -7 Failed allocation memory

int *n; int * n1; n=( int * ) calloc(5, sizeof(int)); // Reserves a block of memory for 5 integers //Decide you need to reallocate more memory later in the program n1= (int *) realloc(n, 10 * sizeof(int));//allocate 10 integers instead of 5 if (n1!=NULL) { n=n1; } else printf("Out of memory!"); realloc() returns null if unable to complete or a pointer to the newly reallocated memory.

 Function declaration  Function definition  Function call

#include using namespace std; int add(int, int); int main(void) { int number1, number2; cout << “Enter the first value to be summed:”; cin >> number1; cout << “\nEnter the second:”; cin >> number2; cout << “\n The sum is: “ << add (number1, number2) <<endl; } int add(int a, int b){return a+b;}

 Write a function, called multiply that multiplies two numbers and returns the result

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(“c:\\folder1\\folder2\\file1.dat”, “r”); if(pRead == NULL) printf(“\nFile cannot be opened\n”); else printf(“\nFile opened for reading\n”); fclose(pRead); }

int main () { FILE * pFile; char c; pFile=fopen("alphabet.txt","wt"); 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%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) ) { // While end of file not reached printf( “%s\n”, name ); // output content of name fscanf( pRead, “%s”, name ); // scan from file next string } fclose(pRead); }

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 ); } fclose(pRead); }

 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 ”); printf(“separated by spaces:”); scanf(“%s%s%f”, fName, lName, &gpa); fprintf(pWrite, “%s \t %s \t %.2f \n”, fName, lName, gpa); fclose(pWrite); }

 Can you write a program that asks the user for their  Name  Phone Number  Bank account balance And then prints this information to a data file called accounts.dat ?

/* exit example */ #include int main () { FILE * pFile; pFile = fopen ("myfile.txt","r"); if (pFile==NULL) { printf ("Error opening file"); exit (EXIT_FAILURE); } else { /* file operations here */ } return 0; }

/* perror example */ #include int main () { FILE * pFile; pFile=fopen ("unexist.ent","rb"); if (pFile==NULL) perror ("The following error occurred"); else fclose (pFile); return 0; }

 void swap (int *a, int *b) ;  void swap (float *c, float *d) ;  void swap (char *p, char *q) ;  The other way is to have different number of input parameters for the function

int boxVolume(int length = 1, int width = 1,int height = 1) { return (length * width * height); } If the function was called with no parameters then the default values will be used.

 Used to go out one level.  If you have a global and local variables with same name, and need to call global from local scope then you need to use ::VariableName

 All your declared variables are automatic.  Static variables keep there values as long as they exist.

 Declare classes  Create objects  3 MAIN PRINCIPLES OF OOP  Data abstraction – hiding data members and implementation of a class behind an interface so that the user of the class corrupt that data  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; }

#include union NumericType { int iValue; long lValue; double dValue; }; int main() { union NumericType Values; // iValue = 10 Values.iValue=9; printf("%d\n", Values.iValue); Values.dValue = 3.1416; printf("%f\n", Values.dValue); system("pause"); } Output: 9 3.1416

 An inline function is one in which the function code replaces the function call directly. #include inline void test(void){ puts("Hello!");} int main () { test(); // This will be replaced with puts("Hello!") on run time return 0; }

 Friend declarations introduce extra coupling between classes  Once an object is declared as a friend, it has access to all non-public members as if they were public  A friend function of a class is defined outside of that class's scope

// friend functions #include using namespace std; class CRectangle { int width, height; public: void set_values (int, int); int area () {return (width * height);} friend CRectangle duplicate (CRectangle); }; void CRectangle::set_values (int a, int b) { width = a; height = b; } CRectangle duplicate (CRectangle rectparam) { CRectangle rectres; rectres.width = rectparam.width*2; rectres.height = rectparam.height*2; return (rectres); } int main () { CRectangle rect, rectb; rect.set_values (2,3); rectb = duplicate (rect); cout << rectb.area(); return 0; } Output: 24

 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 in your slides.  If we consider “Woof” of the dog as speak example.  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"; } // This function is overriding the base class Speak() function 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);// can I do this? fido.Move(); return 0; } 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; } Output: 20 10

 Questions??  Good Luck from REACH in your Test

 data_type array_name [number-of-elements];  Two Dimensional Array array_type array_name [number_of_ROWS][number_of_COLUMNS];

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 data_type array_name [number-of-elements];  Two Dimensional Array array_type array_name [number_of_ROWS][number_of_COLUMNS];

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Presentation on theme: " data_type array_name [number-of-elements];  Two Dimensional Array array_type array_name [number_of_ROWS][number_of_COLUMNS];"— Presentation transcript:

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