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| 22 | <title>Whitespace (GNU C Language Manual)</title>
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| 30 | <link href="Symbol-Index.html" rel="index" title="Symbol Index">
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| 31 | <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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| 32 | <link href="Lexical-Syntax.html" rel="up" title="Lexical Syntax">
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| 57 | <body lang="en">
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| 58 | <span id="Whitespace"></span><div class="header">
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| 59 | <p>
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| 60 | Next: <a href="Comments.html" accesskey="n" rel="next">Comments</a>, Previous: <a href="Characters.html" accesskey="p" rel="prev">Characters</a>, Up: <a href="Lexical-Syntax.html" accesskey="u" rel="up">Lexical Syntax</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Symbol-Index.html" title="Index" rel="index">Index</a>]</p>
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| 61 | </div>
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| 62 | <hr>
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| 63 | <span id="Whitespace-1"></span><h3 class="section">5.3 Whitespace</h3>
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| 64 | <span id="index-whitespace-characters-in-source-files"></span>
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| 65 | <span id="index-space-character-in-source"></span>
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| 66 | <span id="index-tab-character-in-source"></span>
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| 67 | <span id="index-formfeed-in-source"></span>
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| 68 | <span id="index-linefeed-in-source"></span>
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| 69 | <span id="index-newline-in-source"></span>
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| 70 | <span id="index-carriage-return-in-source"></span>
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| 71 | <span id="index-vertical-tab-in-source"></span>
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| 72 |
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| 73 | <p>Whitespace means characters that exist in a file but appear blank in a
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| 74 | printed listing of a file (or traditionally did appear blank, several
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| 75 | decades ago). The C language requires whitespace in order to separate
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| 76 | two consecutive identifiers, or to separate an identifier from a
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| 77 | numeric constant. Other than that, and a few special situations
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| 78 | described later, whitespace is optional; you can put it in when you
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| 79 | wish, to make the code easier to read.
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| 80 | </p>
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| 81 | <p>Space and tab in C code are treated as whitespace characters. So are
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| 82 | line breaks. You can represent a line break with the newline
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| 83 | character (also called <em>linefeed</em> or LF), CR (carriage return), or
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| 84 | the CRLF sequence (two characters: carriage return followed by a
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| 85 | newline character).
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| 86 | </p>
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| 87 | <p>The <em>formfeed</em> character, Control-L, was traditionally used to
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| 88 | divide a file into pages. It is still used this way in source code,
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| 89 | and the tools that generate nice printouts of source code still start
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| 90 | a new page after each “formfeed” character. Dividing code into
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| 91 | pages separated by formfeed characters is a good way to break it up
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| 92 | into comprehensible pieces and show other programmers where they start
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| 93 | and end.
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| 94 | </p>
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| 95 | <p>The <em>vertical tab</em> character, Control-K, was traditionally used to
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| 96 | make printing advance down to the next section of a page. We know of
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| 97 | no particular reason to use it in source code, but it is still
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| 98 | accepted as whitespace in C.
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| 99 | </p>
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| 100 | <p>Comments are also syntactically equivalent to whitespace.
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| 101 | </p>
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| 102 |
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| 103 |
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| 104 |
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| 105 | </body>
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| 106 | </html>
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