How to parse complex string with C++?

Question

I'm trying to figure out how could I parse this string using "sstream" and C++

The format of it is: "string,int,int".

I need to be able to assign the first part of the string which contains an IP address to a std::string.

Here is an example of this string:

std::string("127.0.0.1,12,324");

I would then need to obtain

string someString = "127.0.0.1";
int aNumber = 12;
int bNumber = 324;

I will mention again that I can't use boost library, just sstream :-)

Thanks

Answer 1

Here's a useful tokenization function. It doesn't use streams, but can easily perform the task you require by splitting the string on commas. Then you can do whatever you want with the resulting vector of tokens.

/// String tokenizer.
///
/// A simple tokenizer - extracts a vector of tokens from a 
/// string, delimited by any character in delims.
///
vector<string> tokenize(const string& str, const string& delims)
{
    string::size_type start_index, end_index;
    vector<string> ret;

    // Skip leading delimiters, to get to the first token
    start_index = str.find_first_not_of(delims);

    // While found a beginning of a new token
    //
    while (start_index != string::npos)
    {
        // Find the end of this token
        end_index = str.find_first_of(delims, start_index);

        // If this is the end of the string
        if (end_index == string::npos)
            end_index = str.length();

        ret.push_back(str.substr(start_index, end_index - start_index));

        // Find beginning of the next token
        start_index = str.find_first_not_of(delims, end_index);
    }

    return ret;
}

Answer 2

The C++ String Toolkit Library (Strtk) has the following solution to your problem:

int main()
{
   std::string data("127.0.0.1,12,324");
   string someString;
   int aNumber;
   int bNumber;
   strtk::parse(data,",",someString,aNumber,bNumber);
   return 0;
}

More examples can be found Here

Answer 3

It isn't fancy but you can use std::getline to split the string:

std::string example("127.0.0.1,12,324");
std::string temp;
std::vector<std::string> tokens;
std::istringstream buffer(example);

while (std::getline(buffer, temp, ','))
{
    tokens.push_back(temp);
}

Then you can extract the necessary information from each of the separated strings.

Answer 4

You could do something like this as well I believe (Totally off the top of my head so apologies if i made some mistakes in there) ...

stringstream myStringStream( "127.0.0.1,12,324" );
int ipa, ipb, ipc, ipd;
char ch;
int aNumber;
int bNumber;
myStringStream >> ipa >> ch >> ipb >> ch >> ipc >> ch >> ipd >> ch >> aNumber >> ch >> bNumber;

stringstream someStringStream;
someStringStream << ipa << "." << ipb << "." << ipc << "." << ipd;
string someString( someStringStream.str() );