Ashwin Nanjappa Ashwin Nanjappa - 3 months ago 17
C++ Question

Split a string in C++?

What's the most elegant way to split a string in C++? The string can be assumed to be composed of words separated by whitespace.

(Note that I'm not interested in C string functions or that kind of character manipulation/access. Also, please give precedence to elegance over efficiency in your answer.)

The best solution I have right now is:

#include <iostream>
#include <sstream>
#include <string>

using namespace std;

int main()
{
string s("Somewhere down the road");
istringstream iss(s);

do
{
string sub;
iss >> sub;
cout << "Substring: " << sub << endl;
} while (iss);
}

Answer

For what it's worth, here's another way to extract tokens from an input string, relying only on standard library facilities. It's an example of the power and elegance behind the design of the STL.

#include <iostream>
#include <string>
#include <sstream>
#include <algorithm>
#include <iterator>

int main() {
    using namespace std;
    string sentence = "And I feel fine...";
    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));

... or create the vector directly:

vector<string> tokens{istream_iterator<string>{iss},
                      istream_iterator<string>{}};