Comments (The GNU Algol 68 Compiler)

### 4.1 Comments ¶

In the default modern stropping regime supported by GCC comments are written between `{` and `}` delimiters, and can be nested to arbitrary depth. For example:

    foo +:= 1; { Increment foo.  }

If UPPER stropping is selected, this compiler additionally supports three classical Algol 68 comment styles, in which the symbols marking the beginning of comments are the same than the symbols marking the end of comments and therefore can’t be nested: `comment ... comment`, `co ... co` and `# .. #`. For example:

    comment
      This is a comment.
    comment

    foo := 10; co this is also a comment co
    foo +:= 1; # and so is this.  #

Unless `-std=algol68` is specified in the command line, two styles of nestable comments can be also used with UPPER stropping: the already explained `{ ... }` and a “bold” style that uses `code ... edoc`. For example:

    foo := 10; { this is a nestable comment in brief style.  }
    foo +:= 1; note this is a nestable comment in bold style.  eton.

    note
       "Bold" nestable comments.
    eton

    { "Brief" nestable comments. }

In UPPER stropping all comment styles are available, both classic and nestable. In modern SUPPER stropping, which is based on reserved words, only `{ ... }` is available.