Object-oriented design (OOD)
used in Object-oriented Programming (OOP)
focus is on objects (rather than functions)
object = an instance of an entity; same as a variable
solve the problem by identifying object in the solution & how they interact
Closer look at objects
oobjects are defined by “classes”
oclass = a structured data type including operations
oclasses define data types and operations
owe’ve already used classes & objects (without knowing it) to do I/O & use
string data type
othe iostream library file defines the classes istream and ostream
oThen within the library file, an object cin is defined to be of type istream
oan object cout is defined to be of type ostream
istream cin;
ostream cout;
oin the same way the fstream library defines classes ifstream and
ofstream
othen you can declare your own object of these classes in your program
othe string library defines a class called string
oyou can then create objects of the string class in your program
string firstName;
How do we perform operations using objects in C++?
oobjects have operations ( methods ) associated with them
othe syntax to call a function that is associated with an object is
<objectName>.<functionName>(<parameters>);
cin.get(someChar);
//void function
cout.setf(ios::fixed, ios::floatfield); //void function
length = firstName.length( ); //non-void function
oSome functions are designed in a special way to allow a
special operator to signal a function call
EX: cout << “hello!”; // the characters << are actually a
function call
// the string “hello!” is a parameter
