24 Strings library [strings]

24.3 String classes [string.classes]

24.3.2 Class template basic_­string [basic.string]

24.3.2.6 basic_­string modifiers [string.modifiers]

24.3.2.6.1 basic_­string​::​operator+= [string.op+=]

basic_string& operator+=(const basic_string& str);

basic_string& operator+=(basic_string_view<charT, traits> sv);

basic_string& operator+=(const charT* s);

basic_string& operator+=(charT c);

basic_string& operator+=(initializer_list<charT> il);