In Standard-C, it is allowed to continue Lines with a Backslash („\“). This even works for Single-Line-Comments („//“). But the C-Mode of Emacs does not colour the Continuation-Line right in this Case. In GNU Emacs 24.4.1 (x86_64-pc-linux-gnu, GTK+ Version 3.14.5) of 2015-03-07 on trouble, modified by Debian Configured using: `configure --build x86_64-linux-gnu --prefix=/usr --sharedstatedir=/var/lib --libexecdir=/usr/lib --localstatedir=/var/lib --infodir=/usr/share/info --mandir=/usr/share/man --with-pop=yes --enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.4/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.4/site-lisp:/usr/share/emacs/site-lisp --build x86_64-linux-gnu --prefix=/usr --sharedstatedir=/var/lib --libexecdir=/usr/lib --localstatedir=/var/lib --infodir=/usr/share/info --mandir=/usr/share/man --with-pop=yes --enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.4/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.4/site-lisp:/usr/share/emacs/site-lisp --with-x=yes --with-x-toolkit=gtk3 --with-toolkit-scroll-bars 'CFLAGS=-g -O2 -fstack-protector-strong -Wformat -Werror=format-security -Wall' CPPFLAGS=-D_FORTIFY_SOURCE=2 LDFLAGS=-Wl,-z,relro' Important settings: value of $LC_ALL: en_US.utf8 value of $LANG: de_DE.UTF-8 locale-coding-system: utf-8-unix Major mode: C/l Minor modes in effect: show-paren-mode: t tooltip-mode: t electric-indent-mode: t mouse-wheel-mode: t tool-bar-mode: t menu-bar-mode: t file-name-shadow-mode: t global-font-lock-mode: t font-lock-mode: t auto-composition-mode: t auto-encryption-mode: t auto-compression-mode: t column-number-mode: t line-number-mode: t transient-mark-mode: t abbrev-mode: t Recent input: / / SPC C o m m e n t \ RET s t i l l SPC C o m m e n t RET ESC x r e p TAB o TAB r TAB RET Recent messages: Loading debian-ispell... Loading /var/cache/dictionaries-common/emacsen-ispell-default.el (source)...done Loading debian-ispell...done Loading /var/cache/dictionaries-common/emacsen-ispell-dicts.el (source)...done Loading /etc/emacs/site-start.d/50dictionaries-common.el (source)...done Loading term/xterm...done For information about GNU Emacs and the GNU system, type C-h C-a. (New file) Auto-saving...done Making completion list... [2 times] Load-path shadows: /usr/share/emacs/24.4/site-lisp/debian-startup hides /usr/share/emacs/site-lisp/debian-startup /usr/share/emacs24/site-lisp/dictionaries-common/ispell hides /usr/share/emacs/24.4/lisp/textmodes/ispell /usr/share/emacs24/site-lisp/dictionaries-common/flyspell hides /usr/share/emacs/24.4/lisp/textmodes/flyspell Features: (shadow sort gnus-util mail-extr emacsbug message format-spec rfc822 mml mml-sec mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util help-fns mail-prsvr mail-utils help-mode cc-langs cl-loaddefs cl-lib cc-mode cc-fonts easymenu cc-guess cc-menus cc-cmds cc-styles cc-align cc-engine cc-vars cc-defs xterm time-date paren tooltip electric uniquify ediff-hook vc-hooks lisp-float-type mwheel x-win x-dnd tool-bar dnd fontset image regexp-opt fringe tabulated-list newcomment lisp-mode prog-mode register page menu-bar rfn-eshadow timer select scroll-bar mouse jit-lock font-lock syntax facemenu font-core frame cham georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean japanese hebrew greek romanian slovak czech european ethiopic indian cyrillic chinese case-table epa-hook jka-cmpr-hook help simple abbrev minibuffer nadvice loaddefs button faces cus-face macroexp files text-properties overlay sha1 md5 base64 format env code-pages mule custom widget hashtable-print-readable backquote make-network-process dbusbind gfilenotify dynamic-setting system-font-setting font-render-setting move-toolbar gtk x-toolkit x multi-tty emacs) Memory information: ((conses 16 106480 3340) (symbols 48 20255 0) (miscs 40 41 132) (strings 32 16733 4161) (string-bytes 1 571592) (vectors 16 9569) (vector-slots 8 369435 10826) (floats 8 67 286) (intervals 56 231 0) (buffers 960 13) (heap 1024 8627 714))