Object-Oriented Programming
(OOP)
Lecture No. 14
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Object-Oriented Programming: Student Class with String Data Member, Slides of Object Oriented Programming
The implementation of the student class using composition, where a string data member is used to store the student's name. The constructor, destructor, and member functions of the student and string classes, as well as the main function that demonstrates the usage of the student class.
Typology: Slides
2011/2012
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Object-Oriented Programming
(OOP)
Lecture No. 14
Composition
Consider the following implementationof the student class:
*gpa : floatrollNo : intname : char Student(char * = NULL, int = 0,
float = 0.0);
**Student(const Student &)GetName() const : const char SetName(char ) : void~Student()…
Student
Composition Student::Student(char
*^
_name,
int
roll, float
g){
cout
"Constructor::Student..\n"; if^ (!_name){ name
=^
new char[strlen(_name)+1];
strcpy(name,_name); } else
name
=^
NULL;
rollNumber
=^
roll;
gpa
=^
g;
}
Composition
Student::Student(const
Student
&^
st){
if(str.name
NULL){
name
=^
new char[strlen(st.name)
+^
1];
strcpy(name,
st.name);
} else
name
=^
NULL;
rollNumber
=^
st.roll;
gpa
=^
st.g; }
Composition
►C++: “
its all about code reuse”
►Composition:
Creating objects of one class insideanother class
Has a
”^ relationship:
Bird has a beak Student has a name
Composition
Conceptual notation:
**String()SetString(char ) : voidGetString() const : const char ~String()…
gpa : floatrollNo : intname : StringStudent(char * = NULL, int = 0,
float = 0.0);
**Student(const Student &)GetName() const : StringGetNamePtr() const : const char SetName(char ) : void~Student()…
Student
**string : char ***
String
Composition
String::String(){
cout << "Constructor::String..\n";ptr = NULL; } String::String(const String & str){
if(str.ptr != NULL){string = new char[strlen(str.ptr)+1];
strcpy(ptr, str.ptr);}
Composition
void String::SetString(char * str){
if(ptr != NULL){
delete [] ptr;ptr = NULL; } if(str != NULL){
ptr = new
char[strlen(str)+1];
strcpy(ptr, str); } }
Composition
class
Student{ private:float
gpa; int rollNumber; String
name; public:Student(char*
=NULL,
int=0,float=0.0);
Student(const
Student
void
SetName(const
char
String
GetName()
const;
const
char
*^
GetNamePtr
const
~Student();… };
Composition
Student Student(char * _name,
int roll,
float g){
cout <<"Constructor::Student..\n";name.SetString(_name);rollNumber = roll;gpa = g;
Composition
void Student::SetName(const char * n){
name.SetString(n); } Student::~Student(){
cout <<"Destructor::Student..\n"; }