C++ BOOST string lookup example

This article illustrates the method of BOOST string lookup in C++. Specific methods are as follows:

The BOOST   String lookup example

#include <string>  

#include <iostream>  

#include <algorithm>  

#include <functional>  

#include <boost/algorithm/string/case_conv.hpp>  

#include <boost/algorithm/string/find.hpp>  

  

using namespace std;  

using namespace boost;  

  

int main()  

{    

    cout << "* Find Example *" << endl << endl;  

  

    string str1("abc___cde___efg");  

    string str2("abc");  

  

    // find "cde" substring  

    iterator_range<string::iterator> range=find_first( str1, string("cde") );  

  

    // convert a substring to upper case   

    // note that iterator range can be directly passed to the algorithm  

    to_upper( range );  

  

    cout << "str1 with upper-cased part matching cde: " << str1 << endl;  

  

    // get a head of the string  

    iterator_range<string::iterator> head=find_head( str1, 3 );  

    cout << "head(3) of the str1: " << string( head.begin(), head.end() ) << endl;  

  

    // get the tail  

    head=find_tail( str2, 5 );  

    cout << "tail(5) of the str2: " << string( head.begin(), head.end() ) << endl;  

  

    // char processing  

    char text[]="hello dolly!";  

    iterator_range<char*> crange=find_last(text,"ll");  

  

    // transform the range ( add 1 )  

    transform( crange.begin(), crange.end(), crange.begin(), bind2nd( plus<char>(), 1 ) );  

    // uppercase the range  

    to_upper( crange );  

  

    cout << text << endl;  

  

    cout << endl;  

  

    return 0;  

}

Use of boost decision functions

#include <string>  

#include <iostream>  

#include <functional>  

#include <boost/algorithm/string/predicate.hpp>  

#include <boost/algorithm/string/classification.hpp>  

#include <boost/bind.hpp> 
using namespace std;  

using namespace boost; 
int main()  

{  

    cout << "* Predicate Example *" << endl << endl;  

  

    string str1("123xxx321");  

    string str2("abc");  

  

    // Check if str1 starts with '123'  

    cout << "str1 starts with "123": " <<   

        (starts_with( str1, string("123") )?"true":"false") << endl;   

      

    // Check if str1 ends with '123'  

    cout << "str1 ends with "123": " <<   

        (ends_with( str1, string("123") )?"true":"false") << endl;   

  

    // Check if str1 containes 'xxx'  

    cout << "str1 contains "xxx": " <<   

        (contains( str1, string("xxx") )?"true":"false") << endl;   

  

    // Check if str2 equals to 'abc'  

    cout << "str2 equals "abc": " <<   

        (equals( str2, string("abc") )?"true":"false") << endl;   

  

    // Classification functors and all predicate  

    if ( all(";.,", is_punct() ) )  

    {  

        cout << "";.," are all punctuation characters" << endl;    

    }  

  

    // Classification predicates can be combined   

    if ( all("abcxxx", is_any_of("xabc") && !is_space() ) )  

    {  

        cout << "true" << endl;  

    }  

  

    cout << endl;  

  

    return 0;  

}

Boost replacement example

#include <string>  

#include <iostream>  

#include <iterator>  

//#include <boost/algorithm/string/replace.hpp>  

//#include <boost/algorithm/string/erase.hpp>  

//#include <boost/algorithm/string/case_conv.hpp>  

#include <boost/algorithm/string.hpp>  

  

//Following two includes contain second-layer function.  

//They are already included by first-layer header  

  

//#include <boost/algorithm/string/replace2.hpp>  

//#include <boost/algorithm/string/find2.hpp>  

  

using namespace std;  

using namespace boost;  

  

// uppercase formatter  

/*  

    Convert an input to upper case.   

    Note, that this formatter can be used only on std::string inputs.  

*/  

inline string upcase_formatter(   

    const iterator_range<string::const_iterator>& Replace )  

{  

    string Temp(Replace.begin(), Replace.end());  

    to_upper(Temp);  

    return Temp;  

}  

  

int main()  

{    

    cout << "* Replace Example *" << endl << endl;  

  

    string str1("abc___cde___efg");  

  

    // Erase 6-9th characters from the string  

    cout << "str1 without 6th to 9th character:" <<  

        erase_range_copy( str1, make_iterator_range(str1.begin()+6, str1.begin()+9) ) << endl;  

  

    // Replace 6-9th character with '+++'  

    cout << "str1 with 6th to 9th character replaced with '+++': " <<   

        replace_range_copy(   

            str1, make_iterator_range(str1.begin()+6, str1.begin()+9), "+++" ) << endl;  

  

    cout << "str1 with 'cde' replaced with 'XYZ': ";  

      

    // Replace first 'cde' with 'XYZ'. Modify the input  

    replace_first_copy( ostream_iterator<char>(cout), str1, "cde", "XYZ" );  

    cout << endl;  

      

    // Replace all '___'  

    cout << "str1 with all '___' replaced with '---': " <<   

        replace_all_copy( str1, "___", "---" ) << endl;  

  

    // Erase all '___'  

    cout << "str1 without all '___': " <<   

        erase_all_copy( str1, "___" ) << endl;  

  

    // replace third and 5th occurrence of _ in str1  

    // note that nth argument is 0-based  

    replace_nth( str1, "_", 4, "+" );  

    replace_nth( str1, "_", 2, "+" );  

  

    cout << "str1 with third and 5th occurrence of _ replace: " << str1 << endl;  

  

    // Custom formatter examples  

    string str2("abC-xxxx-AbC-xxxx-abc");  

  

    // Find string 'abc' ignoring the case and convert it to upper case  

    cout << "Upcase all 'abc'(s) in the str2: " <<  

        find_format_all_copy(   

            str2,  

            first_finder("abc", is_iequal()),   

            upcase_formatter );  

      

    cout << endl;  

  

    return 0;  

}

Hope that the article described in the C++ programming to help you.