Splitting a string by a character

Question

I know this is a quite easy problem but I just want to solve it for myself once and for all

I would simply like to split a string into an array using a character as

Answer 1

Take a look at boost::tokenizer

If you'd like to roll up your own method, you can use std::string::find() to determine the splitting points.

Answer 2

Another possibility is to imbue a stream with a locale that uses a special ctype facet. A stream uses the ctype facet to determine what's "whitespace", which it treats as separators. With a ctype facet that classifies your separator character as whitespace, the reading can be pretty trivial. Here's one way to implement the facet:

struct field_reader: std::ctype<char> {

    field_reader(): std::ctype<char>(get_table()) {}

    static std::ctype_base::mask const* get_table() {
        static std::vector<std::ctype_base::mask> 
            rc(table_size, std::ctype_base::mask());

        // we'll assume dates are either a/b/c or a-b-c:
        rc['/'] = std::ctype_base::space;
        rc['-'] = std::ctype_base::space;
        return &rc[0];
    }
};

We use that by using imbue to tell a stream to use a locale that includes it, then read the data from that stream:

std::istringstream in("07/3/2011");
in.imbue(std::locale(std::locale(), new field_reader);

With that in place, the splitting becomes almost trivial -- just initialize a vector using a couple of istream_iterators to read the pieces from the string (that's embedded in the istringstream):

std::vector<std::string>((std::istream_iterator<std::string>(in),
                          std::istream_iterator<std::string>());

Obviously this tends toward overkill if you only use it in one place. If you use it much, however, it can go a long ways toward keeping the rest of the code quite clean.