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There are two ways of rendering comments to as. In both cases the comment is equivalent to one space.

Anything from `/*' through the next `*/' is a comment. This means you may not nest these comments.

       The only way to include a newline ('\n') in a comment
       is to use this sort of comment.
     /* This sort of comment does not nest. */

Anything from the line comment character to the next newline is considered a comment and is ignored. The line comment character is `;' on the ARC; `@' on the ARM; `;' for the H8/300 family; `;' for the HPPA; `#' on the i386 and x86-64; `#' on the i960; `;' for the PDP-11; `;' for picoJava; `#' for Motorola PowerPC; `#' for IBM S/390; `#' for the Sunplus SCORE; `!' for the Renesas / SuperH SH; `!' on the SPARC; `#' on the ip2k; `#' on the m32c; `#' on the m32r; `|' on the 680x0; `#' on the 68HC11 and 68HC12; `#' on the RX; `;' on the TMS320C6X; `#' on the Vax; `;' for the Z80; `!' for the Z8000; `#' on the V850; `#' for Xtensa systems; see Machine Dependencies.

On some machines there are two different line comment characters. One character only begins a comment if it is the first non-whitespace character on a line, while the other always begins a comment.

The V850 assembler also supports a double dash as starting a comment that extends to the end of the line.


To be compatible with past assemblers, lines that begin with `#' have a special interpretation. Following the `#' should be an absolute expression (see Expressions): the logical line number of the next line. Then a string (see Strings) is allowed: if present it is a new logical file name. The rest of the line, if any, should be whitespace.

If the first non-whitespace characters on the line are not numeric, the line is ignored. (Just like a comment.)

                               # This is an ordinary comment.
     # 42-6 "new_file_name"    # New logical file name
                               # This is logical line # 36.

This feature is deprecated, and may disappear from future versions of as.