Operator Keywords

The C++ standard provides operator keywords (Fig. 24.3) that can be used in place of several C++ operators. Operator keywords are useful for programmers who have keyboards that do not support certain characters such as !, &, ^, ~, |, etc.

Figure 24.3. Operator keyword alternatives to operator symbols.

Operator

Operator keyword

Description

Logical operator keywords

&&

and

logical AND

||

or

logical OR

!

not

logical NOT

Inequality operator keyword

!=

not_eq

inequality

Bitwise operator keywords

&

bitand

bitwise AND

|

bitor

bitwise inclusive OR

^

xor

bitwise exclusive OR

~

compl

bitwise complement

Bitwise assignment operator keywords

&=

and_eq

bitwise AND assignment

|=

or_eq

bitwise inclusive OR assignment

^=

xor_eq

bitwise exclusive OR assignment

Figure 24.4 demonstrates the operator keywords. This program was compiled with Microsoft Visual C++ .NET, which requires the header file (line 8) to use the operator keywords. In GNU C++, line 8 should be removed and the program should be compiled as follows:

g++ -foperator-names Fig24_04.cpp -o Fig24_04

 

Figure 24.4. Demonstrating the operator keywords.

(This item is displayed on pages 1208 - 1209 in the print version)

 1 // Fig. 24.4: fig24_04.cpp
 2 // Demonstrating operator keywords.
 3 #include 
 4 using std::boolalpha;
 5 using std::cout;
 6 using std::endl;
 7
 8 #include  // enables operator keywords in Microsoft Visual C++
 9
10 int main()
11 {
12 bool a = true;
13 bool b = false;
14 int c = 2;
15 int d = 3;
16
17 // sticky setting that causes bool values to display as true or false
18 cout << boolalpha;
19
20 cout << "a = " << a << "; b = " << b
21 << "; c = " << c << "; d = " << d;
22
23 cout << "

Logical operator keywords:";
24 cout << "
 a and a: " << ( a and a );
25 cout << "
 a and b: " << ( a and b );
26 cout << "
 a or a: " << ( a or a );
27 cout << "
 a or b: " << ( a or b );
28 cout << "
 not a: " << ( not a );
29 cout << "
 not b: " << ( not b );
30 cout << "
a not_eq b: " << ( a not_eq b );
31
32 cout << "

Bitwise operator keywords:";
33 cout << "
c bitand d: " << ( c bitand d );
34 cout << "
c bit_or d: " << ( c bitor d );
35 cout << "
 c xor d: " << ( c xor d );
36 cout << "
 compl c: " << ( compl c );
37 cout << "
c and_eq d: " << ( c and_eq d );
38 cout << "
 c or_eq d: " << ( c or_eq d );
39 cout << "
c xor_eq d: " << ( c xor_eq d ) << endl;
40 return 0;
41 } // end main
 
 a = true; b = false; c = 2; d = 3

 Logical operator keywords:
 a and a: true
 a and b: false
 a or a: true
 a or b: true
 not a: false
 not b: true
 a not_eq b: true

 Bitwise operator keywords:
 c bitand d: 2
 c bit_or d: 3
 c xor d: 1
 compl c: -3
 c and_eq d: 2
 c or_eq d: 3
 c xor_eq d: 0
 

The compiler option -foperator-names indicates that the compiler should enable use of the operator keywords in Fig. 24.3. Other compilers may not require you to include a header file or to use a compiler option to enable support for these keywords. For example, the Borland C++ 5.6.4 compiler implicitly permits these keywords.


The program declares and initializes two bool variables and two integer variables (lines 1215). Logical operations (lines 2430) are performed with bool variables a and b using the various logical operator keywords. Bitwise operations (lines 3339) are performed with the int variables c and d using the various bitwise operator keywords. The result of each operation is output.

Introduction to Computers, the Internet and World Wide Web

Introduction to C++ Programming

Introduction to Classes and Objects

Control Statements: Part 1

Control Statements: Part 2

Functions and an Introduction to Recursion

Arrays and Vectors

Pointers and Pointer-Based Strings

Classes: A Deeper Look, Part 1

Classes: A Deeper Look, Part 2

Operator Overloading; String and Array Objects

Object-Oriented Programming: Inheritance

Object-Oriented Programming: Polymorphism

Templates

Stream Input/Output

Exception Handling

File Processing

Class string and String Stream Processing

Web Programming

Searching and Sorting

Data Structures

Bits, Characters, C-Strings and structs

Standard Template Library (STL)

Other Topics

Appendix A. Operator Precedence and Associativity Chart

Appendix B. ASCII Character Set

Appendix C. Fundamental Types

Appendix D. Number Systems

Appendix E. C Legacy Code Topics

Appendix F. Preprocessor

Appendix G. ATM Case Study Code

Appendix H. UML 2: Additional Diagram Types

Appendix I. C++ Internet and Web Resources

Appendix J. Introduction to XHTML

Appendix K. XHTML Special Characters

Appendix L. Using the Visual Studio .NET Debugger

Appendix M. Using the GNU C++ Debugger

Bibliography



C++ How to Program
C++ How to Program (5th Edition)
ISBN: 0131857576
EAN: 2147483647
Year: 2004
Pages: 627

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