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| <h3 class="section">3.3 Comments</h3> |
| |
| <p><a name="index-comments-125"></a>There are two ways of rendering comments to <samp><span class="command">as</span></samp>. In both |
| cases the comment is equivalent to one space. |
| |
| <p>Anything from ‘<samp><span class="samp">/*</span></samp>’ through the next ‘<samp><span class="samp">*/</span></samp>’ is a comment. |
| This means you may not nest these comments. |
| |
| <pre class="smallexample"> /* |
| 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. */ |
| </pre> |
| <p><a name="index-line-comment-character-126"></a>Anything from a <dfn>line comment</dfn> character up to the next newline is |
| considered a comment and is ignored. The line comment character is target |
| specific, and some targets multiple comment characters. Some targets also have |
| line comment characters that only work if they are the first character on a |
| line. Some targets use a sequence of two characters to introduce a line |
| comment. Some targets can also change their line comment characters depending |
| upon command-line options that have been used. For more details see the |
| <em>Syntax</em> section in the documentation for individual targets. |
| |
| <p>If the line comment character is the hash sign (‘<samp><span class="samp">#</span></samp>’) then it still has the |
| special ability to enable and disable preprocessing (see <a href="Preprocessing.html#Preprocessing">Preprocessing</a>) and |
| to specify logical line numbers: |
| |
| <p><a name="index-g_t_0023-127"></a><a name="index-lines-starting-with-_0040code_007b_0023_007d-128"></a><a name="index-logical-line-numbers-129"></a>To be compatible with past assemblers, lines that begin with ‘<samp><span class="samp">#</span></samp>’ have a |
| special interpretation. Following the ‘<samp><span class="samp">#</span></samp>’ should be an absolute |
| expression (see <a href="Expressions.html#Expressions">Expressions</a>): the logical line number of the <em>next</em> |
| line. Then a string (see <a href="Strings.html#Strings">Strings</a>) is allowed: if present it is a |
| new logical file name. The rest of the line, if any, should be whitespace. |
| |
| <p>If the first non-whitespace characters on the line are not numeric, |
| the line is ignored. (Just like a comment.) |
| |
| <pre class="smallexample"> # This is an ordinary comment. |
| # 42-6 "new_file_name" # New logical file name |
| # This is logical line # 36. |
| </pre> |
| <p>This feature is deprecated, and may disappear from future versions |
| of <samp><span class="command">as</span></samp>. |
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