C++, Searching and returning value.

Question

For example, lets say I have this string:

"Name, Name2, <b>Name3</b>, Name4, <b>Name5</b>"

I am trying to get whatever value / name is inside the <b> tags. So when I search the char, I get the following in an array:

Name3
Name5

Any ideas? Thanks

Answer 1

For this type of string searching / matching approach, just use boost regex.

Answer 2

start = strstr(s, "<b>")+3;
stop = strstr(start, "</b>");
strncpy(result, start, stop-start);

Don't forget to add error checking.

subsequent matches, for the lazy ones:

s = stop+3;

execute the above code again.

[EDIT] To stop/error checking: check return code of strstr.

Answer 3

Here's a basic version using only STL which assumes that the tags are not nested or otherwise misbehaving

#include <iostream>
#include <string>
#include <vector>

int main()
{
    const std::string TAG_OPEN( "<b>" );
    const std::string TAG_CLOSE( "</b>" );
    const std::string s( "Name, Name2, <b>Name3</b>, Name4, <b>Name5</b>" );

    typedef std::vector< std::string > StringArray;
    StringArray tagContents;

    std::string::size_type index = 0;
    while( index != std::string::npos )
    {
        const std::string::size_type o = s.find( TAG_OPEN, index );
        if ( o == std::string::npos )
        {
            break;
        }

        const std::string::size_type c = s.find( TAG_CLOSE, index );
        if ( c == std::string::npos )
        {
            // mismatched tag, ignore?
            break;
        }

        const std::string::size_type tagContentsStart  = o + TAG_OPEN.size();
        const std::string::size_type tagContentsFinish = c;
        tagContents.push_back(
            s.substr( tagContentsStart
                    , tagContentsFinish - tagContentsStart ) );

        index = c + TAG_CLOSE.size();
    }


    for ( StringArray::const_iterator S  = tagContents.begin();
                                      S != tagContents.end();
                                    ++S )
    {
        std::cout << *S << std::endl;
    }

    return 0;
}

Answer 4

If you refuse to use std::string and insist on using C-style string, you can always be adventurous and use strtok. It has the feature of modifying your text strings.

Please read up on the side-effects of strtok before using it.

I still strongly suggest making a std::string with your chars, then using the std::string for parsing. There are a lot more features with std::string than with C-style strings.