1. Classes Class Data Members & Initializers
Department of Computer and Information Science, School of Science, IUPUI
CSCI 240
Classes Class Data Members & Initializers
Dale Roberts, Lecturer
Computer Science, IUPUI
8/29/2019

2. Class Objects as Members -- Example
class student{ char *name; public: student(char *ip) { name = new char[50]; strcpy(name, ip); } ~student(){delete[] name;} };
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3. Class Objects as Members -- Example
class instructor{ char *name; public: instructor(char *ip) { name = new char[50]; strcpy(name, ip); } ~instructor(){delete[] name;} };
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4. Class Objects as Members -- Example
class csci_c{ student s1, s2; instructor i1; char *location; public: //Constructor Initializer csci_c(char *n1, char *n2, char *n3, char *l) :s1(n1), s2(n2), i1(n3){ location = new char[50]; strcpy(location, l); } ~csci_c(){delete[] location;} };
main() { csci_c fall_class("John","Tom","Henry","SI102");}
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5. Class Objects as Data Members
Data Members can be User Defined Types Having their Constructors
Constructor Initializer is Used
Appropriate Constructors are Invoked on the Order they are Specified in the Class Declaration
Destructor of the Class Containing Members of Other Classes is Called First, Followed by the Member's Destructors in Reverse Order of Declaration
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6. Constructor Initializer
  Specifies the Processing to be Performed Before the Actual Constructor Processing Starts
A List of Entries, Each of Which has:
Identifier of Fundamental Data Type
Identifier of a Class Object
Name of a Base Class -- Inheritance
Each Name is Followed by Its Initialization Values in Parenthesis
Appropriate Constructors are Invoked
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7. Constructor Initializer -- Example
/* Assume the Previous Definitions of Classes "student" and "instructor" are Valid */ class csci_c{ student s1, s2; instructor i1; char *location; int capacity; public: /* Constructor Initializer */ csci_c(char *n1,char *n2,char *n3,char *l,int c) :s1(n1), s2(n2), i1(n3), location(l), capacity(c){} ~csci_c(){} };
main() { csci_c summer("John","Tom","Henry","SL110",20); }
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8. Array of Class Objects -- A Class With a Constructor
Default Constructor is MUST
All the Objects will be Initialized as per the Default Constructor
You can use array initializers to pass a single argument to a constructor of a declared array
There is NO Way to pass an argument to a constructors of a Dynamic Array Declaration
Destructor MUST be Called for EACH ELEMENT in the Array
Automatic Array Objects -- Implicit Destruction
Explicitly Created Objects by new -- delete[] Operator
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9. Array of Objects -- Example
#define size 50
class student{ char *name; public: student() //Default Constructor {name = new char[size]; strcpy(name, "No Name");} student (char *ip): name(ip){} ~student(){delete[] name;} };
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10. Array of Objects -- Example
main(){ /* object array of "student" class all initialized to "No Name" – default constructor */ student s1[size]; /* Initialization -- second constructor */ student s2[2] = {"John", "Tom"}; /* Dynamically created array -- default constructor */ student *s3 = new student[3]; /* Dynamically created object -- default constructor */ student *s4 = new student; /* "s1" and "s2" arrays will be automatically destroyed when "main“ exits. However, array pointed by "s3" and object pointed by "s4", must be deleted. */ delete[] s3; delete s4; }
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11. Acknowledgements
These slides were originally prepared by Rajeev Raje, modified by Dale Roberts.
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