64 lines
5.5 KiB
HTML
64 lines
5.5 KiB
HTML
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<?xml version="1.0" encoding="ISO-8859-1" standalone="no"?>
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<html xmlns="http://www.w3.org/1999/xhtml"><head><title>indent style</title><link rel="stylesheet" href="../../jargon.css" type="text/css"/><meta name="generator" content="DocBook XSL Stylesheets V1.61.0"/><link rel="home" href="../index.html" title="The Jargon File"/><link rel="up" href="../I.html" title="I"/><link rel="previous" href="include-war.html" title="include war"/><link rel="next" href="Indent-o-Meter.html" title="Indent-o-Meter"/></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">indent style</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="include-war.html">Prev</a><EFBFBD></td><th width="60%" align="center">I</th><td width="20%" align="right"><EFBFBD><a accesskey="n" href="Indent-o-Meter.html">Next</a></td></tr></table><hr/></div><dt><a id="indent-style"/><dt xmlns="" id="indent-style"><b>indent style</b>: <span xmlns="http://www.w3.org/1999/xhtml" class="grammar">n.</span></dt></dt><dd><p> [C, C++, and Java programmers] The rules one uses to indent code in
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a readable fashion. There are four major C indent styles, described below;
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all have the aim of making it easier for the reader to visually track the
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scope of control constructs. They have been inherited by C++ and Java,
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which have C-like syntaxes. The significant variable is the placement of
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<tt class="literal">{</tt> and <tt class="literal">}</tt> with respect to the
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statement(s) they enclose and to the guard or controlling statement
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(<b class="command">if</b>, <b class="command">else</b>,
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<b class="command">for</b>, <b class="command">while</b>,
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or <b class="command">do</b>) on the block, if any.</p><p><span class="firstterm">K&R style</span> — Named
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after Kernighan & Ritchie, because the examples in <a href="../K/K-ampersand-R.html"><i class="glossterm">K&R</i></a> are formatted this way. Also
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called <span class="firstterm">kernel style</span> because the Unix
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kernel is written in it, and the ‘One True Brace Style’
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(abbrev. 1TBS) by its partisans. In C code, the body is typically indented
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by eight spaces (or one tab) per level, as shown here. Four spaces are
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occasionally seen in C, but in C++ and Java four tends to be the rule
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rather than the exception.</p><div class="literallayout"><p><br/>
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if<EFBFBD>(<cond>)<29>{<br/>
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><body><br/>
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}<br/>
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</p></div><p><span class="firstterm">Allman style</span> — Named for
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Eric Allman, a Berkeley hacker who wrote a lot of the BSD utilities in it
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(it is sometimes called <span class="firstterm">BSD style</span>).
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Resembles normal indent style in Pascal and Algol. It is the only style
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other than K&R in widespread use among Java programmers. Basic indent
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per level shown here is eight spaces, but four (or sometimes three) spaces
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are generally preferred by C++ and Java programmers.</p><div class="literallayout"><p><br/>
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if<EFBFBD>(<cond>)<br/>
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{<br/>
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><body><br/>
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}<br/>
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</p></div><p><span class="firstterm">Whitesmiths style</span> —
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popularized by the examples that came with Whitesmiths C, an early
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commercial C compiler. Basic indent per level shown here is eight spaces,
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but four spaces are occasionally seen.</p><div class="literallayout"><p><br/>
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if<EFBFBD>(<cond>)<br/>
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>{<br/>
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><body><br/>
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>}<br/>
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</p></div><p><span class="firstterm">GNU style</span> — Used
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throughout GNU EMACS and the Free Software Foundation code, and just about
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nowhere else. Indents are always four spaces per level, with <b class="command">{</b> and <b class="command">}</b> halfway
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between the outer and inner indent levels.</p><div class="literallayout"><p><br/>
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if<EFBFBD>(<cond>)<br/>
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<EFBFBD><EFBFBD>{<br/>
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><body><br/>
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<EFBFBD><EFBFBD>}<br/>
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</p></div><p>Surveys have shown the Allman and Whitesmiths styles to be the most
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common, with about equal mind shares. K&R/1TBS used to be nearly
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universal, but is now much less common in C (the opening brace tends to get
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lost against the right paren of the guard part in an <b class="command">if</b> or <b class="command">while</b>, which
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is a <a href="../B/Bad-Thing.html"><i class="glossterm">Bad Thing</i></a>). Defenders of 1TBS argue that any
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putative gain in readability is less important than their style's relative
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economy with vertical space, which enables one to see more code on one's
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screen at once. The Java Language Specification legislates not only the
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capitalization of identifiers, but where nouns, adjectives, and verbs
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should be in method, class, interface, and variable names (section
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6.8). While the specification stops short of also standardizing on a
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bracing style, all source code originating from Sun Laboratories uses the
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K&R style. This has set a precedent for Java programmers, which most
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follow.</p><p>Doubtless these issues will continue to be the subject of
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<a href="../H/holy-wars.html"><i class="glossterm">holy wars</i></a>.</p></dd><div class="navfooter"><hr/><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="include-war.html">Prev</a><EFBFBD></td><td width="20%" align="center"><a accesskey="u" href="../I.html">Up</a></td><td width="40%" align="right"><EFBFBD><a accesskey="n" href="Indent-o-Meter.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">include war<61></td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"><EFBFBD>Indent-o-Meter</td></tr></table></div></body></html>
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