how to convert regex code in C# to c++

Question

I have this code in C#:

string data = "something ... 1,000 anything 20,000 other thing...";
string pattern = @"[0-9]+([\,|\.][0-9]{1,})*([\.\,][0-9]{1,})?";

MatchCollection collection = Regex.Matches(data, pattern);

foreach (Match item in collection)
{
    Console.WriteLine("{0} - {1} - {2}", item.Value, item.Index, item.Length);
}

Console.WriteLine();
Console.WriteLine("End!");
Console.ReadKey();

... and I tried to convert it in C++ (native code, without .net assemblies), so I get something like this:

void main()
    {
        string data = "something ... 1,000 anything 20,000 other thing...";
        regex pattern("([0-9]+([\\,|\\.][0-9]{1,})*([\\.\\,][0-9]{1,})?)");


        const sregex_token_iterator end;

        for (sregex_token_iterator i(data.begin(), data.end(), pattern); i != end; ++i)
        {
            std::cout << i->str() << "-" << i->length() << std::endl;
        }

        cout << endl << "End!";
        fflush(stdin); 
        getchar(); 
    }

So, how can I get the index of the match?

I don't know C#, but in C++ there is not a standard way to use regex, you need to choose a library. Usually the syntax for regex remains the same — Ruggero Turra
– Ruggero Turra, Commented Oct 17, 2011 at 11:54
Do you want pure regex-free C++ code, code using C++0x regex support or some code using some other regex library? — Matěj Zábský
– Matěj Zábský, Commented Oct 17, 2011 at 11:56
There is even the "older" boost regex library (that was "imported" in C++11) — xanatos
– xanatos, Commented Oct 17, 2011 at 11:58

Stack Overflow is garbage · Accepted Answer · 2011-10-17 11:54:59Z

5

Depending on your compiler, the <regex> header might be available, in which case you can simply rewrite the regular expression using the C++ API, which should be trivial.

If that's not available, <tr1/regex> might be available, or failing that, you can use teh Boost.Regex third party lib.

answered Oct 17, 2011 at 11:54

Stack Overflow is garbage

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3 Comments

Eduardo Spaki Over a year ago

I'm trying to user <tr1/regex>, but, with it, how can I get a "match" collection?

Stack Overflow is garbage Over a year ago

Have you looked at your compiler's documentation for the header? :)

Kate Gregory Over a year ago

@Eduardo - update your question retaining the c# code but explaining you're using tr1/regex, pasting in your code, and explaining what your problem is (compile error? bad results?) for best answers.

Eduardo Spaki · Accepted Answer · 2011-10-18 12:26:14Z

0

I solved this way:

struct MatchInfo
{
    string value;
    int index;
    int length;
};

vector<MatchInfo> DoRegex(string data, string pattern)
{
    regex patternRegex(pattern);
    sregex_token_iterator end;
    vector<MatchInfo> result;

    for (sregex_token_iterator i(data.begin(), data.end(), patternRegex); i != end; ++i)
    {
        MatchInfo item;

        item.index = i->first - data.begin();
        item.length = i->length();
        item.value = i->str();

        result.push_back(item);
    }

    return result;
}

answered Oct 18, 2011 at 12:26

Eduardo Spaki

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