How can I tokenize a C++ string?

Question

Duplicate:

How do I tokenize a string in C++?

I have a character array in C++.

arr="abc def ghi"

I want to get the strings "abc" "def" "ghi" out of the string. Are there any built in functions to do this?

Answer 1

Sure you can use the stringstream class and the extraction operators:

stringstream str("abc def ghi");
string a, b, c;
str >> a >> b >> c; // ta da

Answer 2

Building on 1800's excellent answer:

#include <iterator>
#include <sstream>
#include <string>
#include <vector>

using std::istream_iterator;
using std::istringstream;
using std::string;
using std::vector;

vector<string>
cheap_tokenise(string const& input)
{
    istringstream str(input);
    istream_iterator<string> cur(str), end;
    return vector<string>(cur, end);
}

Geekery ahead: I would have liked to use pass-by-value of the string, due to this article: Move constructors. But that technique is currently moot, since basic_istringstream's constructor takes the string by const reference, and (in basic_stringbuf's constructor) copies it. I dream of better days ahead, when the standard library (and common compilers!) supports the techniques mentioned in that article. :-)

Answer 3

This task is more commonly called string tokenizing. There was a thread: http://stackoverflow.com/questions/53849/how-do-i-tokenize-a-string-in-c

To conclude. There are a couple of way to that. What is the best depends on what api you want to\need to use.

• c-style: strtok() function
• stl: std::stringstream
• boost: boost::tokenizer, boost::split