PCRE PartialMatch dynamic number of groups

My app has user defined regular expression patterns which may contain up to 3 capturing groups. Is there a better way to implement the following code?

std::string glyph1, glyph2, glyph3;

switch (regex.NumberOfCapturingGroups())
{
    case 0:
    default:
        found = regex.PartialMatch(word);
        break;
    case 1:
        found = regex.PartialMatch(word, &glyph1);
        break;
    case 2:
        found = regex.PartialMatch(word, &glyph1, &glyph2);
        break;
    case 3:
        found = regex.PartialMatch(word, &glyph1, &glyph2, &glyph3);
        break;
}

if (found) {
    // ...
}

Unfortunately, the returned value is false if the regex would match but there were less capturing groups then requested.