Split a String in C++

There are many ways to split a string in C++, but what’s the most elegant way to split a string in C++? May be we can find it step by step. The most simple and direct way is use istringstream to split.

If the delimiter is whitespace, we could simply code like thie and print substrings:

std::string s("Split a string in C++");
std::istringstream iss(s);

do 
{
    std::string sub;
    iss >> sub;
    if(!sub.empty())
        std::cout << "Substring: " << sub << std::endl;
} while (iss);

While when the delimiter is not whitespace, we need think about other way to resolve this problem. If you ever have used vector container in C++ STL, you can combine it figure out more general solution. We could create a function like this:

typedef std::vector<std::string> StringVector;

StringVector& splitString(const std::string &s, char delim, StringVector &elems)
{
    std::stringstream ss(s);
    std::string item;
    while (std::getline(ss, item, delim))
    {
        elems.push_back(item);
    }
    return elems;
}

May be above solution is more elegent then first one, but it still use stringstream, while structure and some string class’s method, the STL’s power is not incarnated. The later solution will embody the elegence and power of STL’s design.

string sentence = "Split a string in C++";
istringstream iss(sentence);
copy(istream_iterator<string>(iss),
     istream_iterator<string>(),
     ostream_iterator<string>(cout, "\n"));

Instead of copying the extracted tokens to an output stream, one could insert them into a container, using the same generic copy algorithm.

vector<string> tokens;
copy(istream_iterator<string>(iss),
     istream_iterator<string>(),
     back_inserter(tokens));

So simple code, it seems elegent, but its delimiter must be whitespace, it’s not a general solution.

Conclusion: There is not a standard solution in C++, neither in STL, so usual and common operation on string, why C++ not provide a method in string class.

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