1. Classes Member Qualifiers
Department of Computer and Information Science, School of Science, IUPUI
CSCI 240
Classes Member Qualifiers
Dale Roberts, Lecturer
Computer Science, IUPUI
8/15/2019

2. Member Functions -- Qualifiers
inline Member Functions
Function Bodies are Substituted for the Function Call At Compile Time
All the Member Functions Defined within the Class Definition are Implicitly Inline
If Defined Outside the Class Definition, inline Qualifier is Required
Faster Execution
static Member Functions
Exist Before Any Class Instantiation -- Access Only the Static Class Members
const Member Functions
CANNOT Change Data Members
The ONLY ONE that can Process Constant Objects
Can also Process Non-Constant Objects
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3. inline Member Functions -- Example
class student{ int ss, credits; public: int get_ss(){return ss;} //Implicitly "inline" inline int get_credits(); //Explicitly "inline" };
//Explicitly "inline" int student::get_credits() {return credits;}
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4. Nested Classes A Class Contained in Another Class
Multiple Levels of Nesting Are Allowed
Usual Scoping Rules Apply
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5. Nested Classes -- Example
class one{ //Class "two" is nested inside the class "one" int a; public: class two{ int b; public: two(){b = 10;} void print_b() {cout << "two's b: " << b << endl;} }; two one_two;
one(){a = 100;} void print_a() {cout << "one's a: " << a << endl;} };
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6. Nested Classes -- Example
main(){ one s1; //s1 is an object of "one" s1.print_a(); //a = s1.one_two.print_b(); //b = 10
//Object of class "two" defined inside "one" one::two s2; s2.print_b(); //b = 10 }
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7. Constant Data Members Principle of least privilege Keyword const
Only give objects permissions they need, no more
Keyword const
Specify that an object is not modifiable
Any attempt to modify the object is a syntax error
Example
const Time noon( 12, 0, 0 );
Declares a const object noon of class Time and initializes it to 12
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8. Constant Member Functions
const objects require const functions
Member functions declared const cannot modify their object
const must be specified in function prototype and definition
Prototype:
ReturnType FunctionName(param1,param2…) const;
Definition:
ReturnType FunctionName(param1,param2…) const { …}
Example:
int A::getValue() const { return privateDataMember };
Returns the value of a data member but doesn’t modify anything so is declared const
Constructors / Destructors cannot be const
They need to initialize variables, therefore modifying them
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9. Constant Members and Functions
Member initializer syntax
All data members can be initialized using member initializer syntax
constructor for Increment is modified as follows:
Increment::Increment( int c, int i ) : increment( i ) { count = c; }
: increment( i ) initializes increment to i
consts and references must be initialized using member initializer syntax
Multiple member initializers
Use comma-separated list after the colon
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10. const -- Example 
class student{ int ss, credits; public: student():ss(0), credits(0){} //const member function cannot modify the data member int get_ss() const {return ss;} int get_credits(){return credits;} };
main(){ student s1; const student s2; s1.get_ss(); s1.get_credits(); s2.get_ss(); //constant object s2.get_credits(); //ERROR!!! Cannot call a non-constant function }
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11. Acknowledgements
These slides were originally prepared by Rajeev Raje, modified by Dale Roberts.
8/15/2019