How to use stringstream to separate comma separated strings

I've got the following code:

std::string str = "abc def,ghi";
std::stringstream ss(str);

string token;

while (ss >> token)
{
    printf("%s\n", token.c_str());
}

The output is:

abc
def,ghi

So the stringstream::>> operator can separate strings by space but not by comma. Is there anyway to modify the above code so that I can get the following result?

input: "abc,def,ghi"

output:
abc
def
ghi