.NODE

Finding Strings and Characters in a string

Class string provides const member functions for finding substrings and characters in a string. Figure 18.6 demonstrates the find functions.

Figure 18.6. Demonstrating the string find functions.

(This item is displayed on pages 894 - 895 in the print version)

 1 // Fig. 18.6: Fig18_06.cpp
 2 // Demonstrating the string find member functions.
 3 #include 
 4 using std::cout;
 5 using std::endl;
 6
 7 #include 
 8 using std::string;
 9
10 int main()
11 {
12 string string1( "noon is 12 pm; midnight is not." );
13 int location;
14
15 // find "is" at location 5 and 25
16 cout << "Original string:
" << string1
17 << "

(find) "is" was found at: " << string1.find( "is" ) 
18 << "
(rfind) "is" was found at: " << string1.rfind( "is" );
19
20 // find 'o' at location 1
21 location = string1.find_first_of( "misop" );
22 cout << "

(find_first_of) found '" << string1[ location ]
23 << "' from the group "misop" at: " << location;
24
25 // find 'o' at location 29
26 location = string1.find_last_of( "misop");
27 cout << "

(find_last_of) found '" << string1[ location ]
28 << "' from the group "misop" at: " << location;
29
30 // find '1' at location 8
31 location = string1.find_first_not_of( "noi spm" );
32 cout << "

(find_first_not_of) '" << string1[ location ]
33 << "' is not contained in "noi spm" and was found at:"
34 << location;
35
36 // find '.' at location 12
37 location = string1.find_first_not_of( "12noi spm" );
38 cout << "

(find_first_not_of) '" << string1[ location ]
39 << "' is not contained in "12noi spm" and was "
40 << "found at:" << location << endl;
41
42 // search for characters not in string1
43 location = string1.find_first_not_of( 
44 "noon is 12 pm; midnight is not." );
45 cout << "
find_first_not_of("noon is 12 pm; midnight is not.")"
46 << " returned: " << location << endl;
47 return 0;
48 } // end main
 
 Original string:
 noon is 12 pm; midnight is not.

 (find) "is" was found at: 5
 (rfind) "is" was found at: 25

 (find_first_of) found 'o' from the group "misop" at: 1

 (find_last_of) found 'o' from the group "misop" at: 29

 (find_first_not_of) '1' is not contained in "noi spm" and was found at:8

 (find_first_not_of) '.' is not contained in "12noi spm" and was found at:12

 find_first_not_of("noon is 12 pm; midnight is not.") returned: -1
 

String string1 is declared and initialized in line 12. Line 17 attempts to find "is" in string1 using function find. If "is" is found, the subscript of the starting location of that string is returned. If the string is not found, the value string::npos (a public static constant defined in class string) is returned. This value is returned by the string find related functions to indicate that a substring or character was not found in the string.

Line 18 uses member function rfind to search string1 backward (i.e., right-to-left). If "is" is found, the subscript location is returned. If the string is not found, string::npos is returned. [Note: The rest of the find functions presented in this section return the same type unless otherwise noted.]

Line 21 uses member function find_first_of to locate the first occurrence in string1 of any character in "misop". The searching is done from the beginning of string1. The character 'o' is found in element 1.

Line 26 uses member function find_last_of to find the last occurrence in string1 of any character in "misop". The searching is done from the end of string1. The character 'o' is found in element 29.

Line 31 uses member function find_first_not_of to find the first character in string1 not contained in "noi spm". The character '1' is found in element 8. Searching is done from the beginning of string1.

Line 37 uses member function find_first_not_of to find the first character not contained in "12noi spm". The character '.' is found in element 12. Searching is done from the end of string1.

Lines 4344 use member function find_first_not_of to find the first character not contained in "noon is 12 pm; midnight is not.". In this case, the string being searched contains every character specified in the string argument. Because a character was not found, string::npos (which has the value 1 in this case) is returned.

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

show all menu





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

Flylib.com © 2008-2017.
If you may any questions please contact us: flylib@qtcs.net