//Get the action:
nPos1 = line.find(tag_start);
nPos2 = line.find( " ", nPos1 + tag_start.length); //nPos2 now has the index of the first space
the last line is throwing a compilier error because nPos + tag_start.length is not a valid operation. I thought std::string.legnth (tag_start is a std::string) returns type size_t? What am I doing wrong?