strtok() functionality in C++

[Tydr Schnubbis]

Is there a "C++ way" of doing what strtok() does, or should I just
convert string objects into char arrays and use strtok()? I couldn't
find a C++ way that is as straight forward as using strtok().

Would the following be considered "good" C++ style?

s = strtok(line.c_str(), " \t\n");
while (s) {
/* use s here */
s = strtok(NULL, " \t\n");
}

 

[Mike Wahler]

Is there a "C++ way" of doing what strtok() does,

Yes. strtok() (It's as much a part of C++ as it is of C).

or should I just convert string objects into char arrays and use strtok()?
I couldn't find a C++ way that is as straight forward as using strtok().

Would the following be considered "good" C++ style?

s = strtok(line.c_str(), " \t\n");
while (s) {
/* use s here */
s = strtok(NULL, " \t\n");
}

That depends entirely upon your needs.

You can indeed tokenize a std::string object in various
ways. One tool to that end is std::string::find_first_of()
(which will locate a delimiter from a specified set,
but doesn't replace it with a NULL as does strtok())

-Mike

 

[John Harrison]

Is there a "C++ way" of doing what strtok() does, or should I just
convert string objects into char arrays and use strtok()? I couldn't
find a C++ way that is as straight forward as using strtok().

Would the following be considered "good" C++ style?

s = strtok(line.c_str(), " \t\n");
while (s) {
/* use s here */
s = strtok(NULL, " \t\n");
}

No it should not compile. strtok modifies it's argument and c_str()
returns a const char*.

There is no built in C++ string tokeniser. It's not too hard to write
your own especially if you keep it simple, or you could get a third
party one, for instance

http://www.boost.org/libs/tokenizer/index.html

john

 

[int2str]

Is there a "C++ way" of doing what strtok() does, or should I just
convert string objects into char arrays and use strtok()? I couldn't
find a C++ way that is as straight forward as using strtok().

Would the following be considered "good" C++ style?

s = strtok(line.c_str(), " \t\n");
while (s) {
/* use s here */
s = strtok(NULL, " \t\n");
}

If whitespace is all you need as separators, then this should work for
you:

std::istringstream iss( line );
std::string token;
while( iss >> token )
{
// use 'token' here
}

 

[Tydr Schnubbis]

If whitespace is all you need as separators, then this should work for
you:

std::istringstream iss( line );
std::string token;
while( iss >> token )
{
// use 'token' here
}

Thanks, that was just what I was looking for. Simpler and cleaner than
using strtok, as long as you don't require the extra flexibility.

 

[Niklas Norrthon]

Thanks, that was just what I was looking for. Simpler and cleaner
than using strtok, as long as you don't require the extra flexibility.

And if you do need the extra flexibility: (untested)

string next_token(const string& line, const string& delim, string::size_type& first)
{
string::size_type last = line.find_first_of(delim, first);
string next(line.substr(first, last));
first = last;
return next;
}

/Niklas Norrthon