Color declared variables

Question

I'm looking for a simple way to make emacs remember of declared variable in a single function in C/C++. By "simple", I mean without any external package, just with some elisp lines in configuration files.

My default Emacs configuration colors variables names in yellow on declaration, but let them white on use.

char toto; // 'char' is green, 'toto' is yellow

toto = 42; // 'toto' is white

I would like to make every "toto" of the same function/scope colored in yellow as well.

I've already looked on this question but I would like something simpler. I also tried to do something with font-lock mode, but I didn't succeed to make something adaptable to variable names.

I already have an idea for C++ class member names (using a name pattern), so I just want a local variable match here.

Answer 1

You could muster a regexp for your variable scheme, something that matches (pseudo regexp code)[char|other|types] [a-z]; and [a-z] =*; and add it to the font-lock keyword list for your mode ; From the manual at the Customizing-Keywords page :

For example, the following code adds two fontification patterns for C mode: one to fontify the word ‘FIXME’, even in comments, and another to fontify the words ‘and’, ‘or’ and ‘not’ as keywords.

 (font-lock-add-keywords 'c-mode
  '(("\\<\\(FIXME\\):" 1 font-lock-warning-face prepend)
    ("\\<\\(and\\|or\\|not\\)\\>" . font-lock-keyword-face)))

This example affects only C mode proper. To add the same patterns to C mode and all modes derived from it, do this instead:

 (add-hook 'c-mode-hook
  (lambda ()
   (font-lock-add-keywords nil
    '(("\\<\\(FIXME\\):" 1 font-lock-warning-face prepend)
      ("\\<\\(and\\|or\\|not\\)\\>" .
       font-lock-keyword-face)))))