Additional C++ Class Features in Java

Drawer Code 3/9 in Java Additional C++ Class Features
Additional C++ Class Features
Code-39 Creation In Java
Using Barcode creation for Java Control to generate, create Code39 image in Java applications.
1 2 3 4 5 6 7
Drawing Bar Code In Java
Using Barcode encoder for Java Control to generate, create bar code image in Java applications.
boo1 Rational : : operator !
Barcode Decoder In Java
Using Barcode recognizer for Java Control to read, scan read, scan image in Java applications.
const
Code 3 Of 9 Encoder In Visual C#
Using Barcode printer for VS .NET Control to generate, create ANSI/AIM Code 39 image in Visual Studio .NET applications.
return !numer;
USS Code 39 Creator In VS .NET
Using Barcode printer for ASP.NET Control to generate, create Code 39 Full ASCII image in ASP.NET applications.
const Rational
Code39 Creation In .NET Framework
Using Barcode printer for .NET Control to generate, create Code 39 image in Visual Studio .NET applications.
Rational::operator+(
Code 39 Generator In Visual Basic .NET
Using Barcode creation for .NET framework Control to generate, create Code-39 image in .NET applications.
const
Print UPC - 13 In Java
Using Barcode generation for Java Control to generate, create EAN-13 image in Java applications.
return *this; 9 1 10 11 Rational Rational: :operator-( ) const 12 { 13 return Rational( -numer, denom ) ; 14 1
Code 39 Full ASCII Encoder In Java
Using Barcode creation for Java Control to generate, create ANSI/AIM Code 39 image in Java applications.
Additional unary operators (three of three) for the Rational class
DataMatrix Printer In Java
Using Barcode maker for Java Control to generate, create Data Matrix image in Java applications.
the negative of the current object The return must be by copy because the new object is a local variable However, a trap lurks in operator-If the word Rational is omitted from line 13, the comma operator evaluates ( -numer,denom 1 as denom,and then an implicit conversion gives the rational denom/1,which is returned
Draw Code 128 Code Set A In Java
Using Barcode maker for Java Control to generate, create Code 128B image in Java applications.
What Can Be Overloaded
Make UCC-128 In Java
Using Barcode encoder for Java Control to generate, create UCC - 12 image in Java applications.
In C++, all but four operators can be overloaded The four nonoverloadable operators are , *, : , and s i zeo f Operator precedence cannot be changed That is, a+b*c is always a+ (b*c) Arity (whether an operator is unary or binary) cannot be changed so, for example, we cannot write a unary / operator or a binary - operator Finally, only existing operators can be overloaded, and new operators cannot be created
Paint ANSI/AIM I-2/5 In Java
Using Barcode encoder for Java Control to generate, create Uniform Symbology Specification ITF image in Java applications.
Input and Output and Friends
Drawing Bar Code In VS .NET
Using Barcode encoder for VS .NET Control to generate, create bar code image in .NET applications.
The remaining operators in the Rational class are << and >>, which, as discussed in Appendix A, are used for output and input When we make the call
Create USS Code 39 In VB.NET
Using Barcode maker for Visual Studio .NET Control to generate, create Code-39 image in Visual Studio .NET applications.
cout << rl;
Printing Bar Code In .NET Framework
Using Barcode printer for ASP.NET Control to generate, create bar code image in ASP.NET applications.
/ / Output Rational rl
Printing Barcode In Visual Basic .NET
Using Barcode generation for .NET Control to generate, create bar code image in .NET applications.
the operator<< takes an ostream and a Rational as parameters Both parameters are passed by reference The operator<< returns a reference to an ostream so that output calls can be concatenated A similar situation occurs for the operator>>,the only significant difference being that the Rational parameter is not a constant reference
Data Matrix ECC200 Creation In C#.NET
Using Barcode generation for Visual Studio .NET Control to generate, create Data Matrix image in VS .NET applications.
Input and output can be defined by overloading << and
Code 3/9 Encoder In Visual C#.NET
Using Barcode encoder for VS .NET Control to generate, create Code-39 image in VS .NET applications.
Consequently, we arrive at the following prototypes for operator<< and operator>>:
Generate Bar Code In Visual Studio .NET
Using Barcode printer for .NET Control to generate, create bar code image in .NET applications.
ostream istream
operator<<( ostream operator>>( istream
out, const Rational in, Rational
); );
These are not member functions because, when they are called, a Rational is not the controlling object The only class that these could possibly be members of would be the ostream or istream class, in which case the first parameter would not be present For example, ostream has a member function for int output:
ostream
operator<<( int value ) ;
Friends are functions that are exempt from the usual private access restrictions
Needless to say, we cannot add member functions to ostream every time we design a new class Consequently, the input and output functions for Rational are stand-alone functions and are not members of any class They are declared in global scope and are used just like any other function Figure 220 shows the implementation of these functions Note again that no scope resolution operator is attached to their names The input routine reads a fraction or a single integer, as appropriate, and then normalizes the fraction We have not attempted any of the error checking required in a serious implementation Likewise, the output routine is fairly simple and works by calling-preexisting output routines as needed4 You may have noticed something strange in Figure 220: If numer and denom are private data members, how can a nonmember function access it Under normal circumstances it cannot To get around that restriction, we specified in the class interface (at lines 71 to 74 in Figure 213) that these functions are friends, which are exempt from the usual privte access restrictions Notice that only the class can give additional access, and so this does not violate information-hiding principles In general, classes should not have too many friends Section 241 discusses an alternate strategy and Exercise 232 asks you to rewrite the Rational class to avoid the use of friends
Some Common Idioms
In this section we discuss three idioms:
1 a technique that allows us to write global functions without using friend declarations:
4 lnput and output are discussed in Section A2
Some Common l d i o m y m
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44