| [29] | 1 | <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> |
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| 9 | |
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| 10 | <title>Introduction</title> |
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| 11 | </head> |
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| 12 | |
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| 13 | <body bgcolor="#FFFFFF"> |
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| 14 | <p><img src="../../boost.png" alt="C++ Boost" width="277" height= |
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| 15 | "86"><br></p> |
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| 16 | |
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| 17 | <h1 align="center">Introduction</h1> |
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| 18 | |
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| 19 | <p align="left">The boost Tokenizer package provides a flexible and easy to |
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| 20 | use way to break of a string or other character sequence into a series of |
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| 21 | tokens. Below is a simple example that will break up a phrase into |
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| 22 | words.</p> |
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| 23 | |
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| 24 | <div align="left"> |
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| 25 | <pre> |
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| 26 | // simple_example_1.cpp |
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| 27 | #include<iostream> |
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| 28 | #include<boost/tokenizer.hpp> |
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| 29 | #include<string> |
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| 30 | |
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| 31 | int main(){ |
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| 32 | using namespace std; |
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| 33 | using namespace boost; |
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| 34 | string s = "This is, a test"; |
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| 35 | tokenizer<> tok(s); |
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| 36 | for(tokenizer<>::iterator beg=tok.begin(); beg!=tok.end();++beg){ |
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| 37 | cout << *beg << "\n"; |
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| 38 | } |
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| 39 | } |
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| 40 | </pre> |
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| 41 | </div> |
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| 42 | |
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| 43 | <p align="left">You can choose how the string gets broken up. You do this |
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| 44 | by specifying the TokenizerFunction. If you do not specify anything, the |
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| 45 | default TokenizerFunction is char_delimiters_separator<char> which |
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| 46 | defaults to breaking up a string based on space and punctuation. Here is an |
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| 47 | example of using another TokenizerFunction called escaped_list_separator. |
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| 48 | This TokenizerFunction parses a superset of comma separated value (csv) |
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| 49 | lines. The format looks like this</p> |
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| 50 | |
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| 51 | <p align="left">Field 1,"putting quotes around fields, allows commas",Field |
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| 52 | 3</p> |
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| 53 | |
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| 54 | <p align="left">Below is an example that will break the previous line into |
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| 55 | its 3 fields</p> |
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| 56 | |
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| 57 | <div align="left"> |
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| 58 | <pre> |
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| 59 | // simple_example_2.cpp |
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| 60 | #include<iostream> |
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| 61 | #include<boost/tokenizer.hpp> |
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| 62 | #include<string> |
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| 63 | |
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| 64 | int main(){ |
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| 65 | using namespace std; |
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| 66 | using namespace boost; |
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| 67 | string s = "Field 1,\"putting quotes around fields, allows commas\",Field 3"; |
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| 68 | tokenizer<escaped_list_separator<char> > tok(s); |
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| 69 | for(tokenizer<escaped_list_separator<char> >::iterator beg=tok.begin(); beg!=tok.end();++beg){ |
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| 70 | cout << *beg << "\n"; |
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| 71 | } |
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| 72 | } |
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| 73 | </pre> |
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| 74 | </div> |
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| 75 | |
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| 76 | <p align="left">Finally, for some TokenizerFunctions you have to pass in |
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| 77 | something into the constructor in order to do anything interesting. An |
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| 78 | example is offset_separator. This class breaks a string into tokens based |
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| 79 | on offsets for example</p> |
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| 80 | |
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| 81 | <p align="left">12252001 when parsed using offsets of 2,2,4 becomes 12 25 |
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| 82 | 2001. Below is an example to parse this.</p> |
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| 83 | |
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| 84 | <div align="left"> |
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| 85 | <pre> |
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| 86 | // simple_example_3.cpp |
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| 87 | #include<iostream> |
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| 88 | #include<boost/tokenizer.hpp> |
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| 89 | #include<string> |
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| 90 | |
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| 91 | int main(){ |
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| 92 | using namespace std; |
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| 93 | using namespace boost; |
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| 94 | string s = "12252001"; |
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| 95 | int offsets[] = {2,2,4}; |
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| 96 | offset_separator f(offsets, offsets+3); |
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| 97 | tokenizer<offset_separator> tok(s,f); |
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| 98 | for(tokenizer<offset_separator>::iterator beg=tok.begin(); beg!=tok.end();++beg){ |
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| 99 | cout << *beg << "\n"; |
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| 100 | } |
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| 101 | } |
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| 102 | </pre> |
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| 103 | </div> |
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| 104 | |
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| 105 | <p align="left"> </p> |
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| 106 | <hr> |
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| 107 | |
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| 108 | <p><a href="http://validator.w3.org/check?uri=referer"><img border="0" src= |
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| 109 | "http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01 Transitional" |
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| 110 | height="31" width="88"></a></p> |
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| 111 | |
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| 112 | <p>Revised |
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| 113 | <!--webbot bot="Timestamp" s-type="EDITED" s-format="%d %B, %Y" startspan -->25 December, 2006<!--webbot bot="Timestamp" endspan i-checksum="38518" --></p> |
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| 114 | |
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| 115 | <p><i>Copyright © 2001 John R. Bandela</i></p> |
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| 116 | |
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| 117 | <p><i>Distributed under the Boost Software License, Version 1.0. (See |
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| 118 | accompanying file <a href="../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or |
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| 119 | copy at <a href= |
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| 120 | "http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</a>)</i></p> |
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| 121 | </body> |
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| 122 | </html> |
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