diveintopython 5.4-2ubuntu2 / usr / share / doc / diveintopython / html / getting_to_know_python / indenting_code.html

This file is indexed.

/usr/share/doc/diveintopython/html/getting_to_know_python/indenting_code.html is in diveintopython 5.4-2ubuntu2.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below. 

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
<!DOCTYPE html
  PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
   <head>
      <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
   
      <title>2.5.&nbsp;Indenting Code</title>
      <link rel="stylesheet" href="../diveintopython.css" type="text/css">
      <link rev="made" href="mailto:f8dy@diveintopython.org">
      <meta name="generator" content="DocBook XSL Stylesheets V1.52.2">
      <meta name="keywords" content="Python, Dive Into Python, tutorial, object-oriented, programming, documentation, book, free">
      <meta name="description" content="Python from novice to pro">
      <link rel="home" href="../toc/index.html" title="Dive Into Python">
      <link rel="up" href="index.html" title="Chapter&nbsp;2.&nbsp;Your First Python Program">
      <link rel="previous" href="everything_is_an_object.html" title="2.4.&nbsp;Everything Is an Object">
      <link rel="next" href="testing_modules.html" title="2.6.&nbsp;Testing Modules">
   </head>
   <body>
      <table id="Header" width="100%" border="0" cellpadding="0" cellspacing="0" summary="">
         <tr>
            <td id="breadcrumb" colspan="5" align="left" valign="top">You are here: <a href="../index.html">Home</a>&nbsp;&gt;&nbsp;<a href="../toc/index.html">Dive Into Python</a>&nbsp;&gt;&nbsp;<a href="index.html">Your First Python Program</a>&nbsp;&gt;&nbsp;<span class="thispage">Indenting Code</span></td>
            <td id="navigation" align="right" valign="top">&nbsp;&nbsp;&nbsp;<a href="everything_is_an_object.html" title="Prev: &#8220;Everything Is an Object&#8221;">&lt;&lt;</a>&nbsp;&nbsp;&nbsp;<a href="testing_modules.html" title="Next: &#8220;Testing Modules&#8221;">&gt;&gt;</a></td>
         </tr>
         <tr>
            <td colspan="3" id="logocontainer">
               <h1 id="logo"><a href="../index.html" accesskey="1">Dive Into Python</a></h1>
               <p id="tagline">Python from novice to pro</p>
            </td>
            <td colspan="3" align="right">
               <form id="search" method="GET" action="http://www.google.com/custom">
                  <p><label for="q" accesskey="4">Find:&nbsp;</label><input type="text" id="q" name="q" size="20" maxlength="255" value=" "> <input type="submit" value="Search"><input type="hidden" name="cof" value="LW:752;L:http://diveintopython.org/images/diveintopython.png;LH:42;AH:left;GL:0;AWFID:3ced2bb1f7f1b212;"><input type="hidden" name="domains" value="diveintopython.org"><input type="hidden" name="sitesearch" value="diveintopython.org"></p>
               </form>
            </td>
         </tr>
      </table>
      <!--#include virtual="/inc/ads" -->
      <div class="section" lang="en">
         <div class="titlepage">
            <div>
               <div>
                  <h2 class="title"><a name="odbchelper.indenting"></a>2.5.&nbsp;Indenting Code
                  </h2>
               </div>
            </div>
            <div></div>
         </div>
         <div class="abstract">
            <p><span class="application">Python</span> functions have no explicit <tt class="literal">begin</tt> or <tt class="literal">end</tt>, and no curly braces to mark where the function code starts and stops.  The only delimiter is a colon (<tt class="literal">:</tt>) and the indentation of the code itself.
            </p>
         </div>
         <div class="example"><a name="d0e4759"></a><h3 class="title">Example&nbsp;2.5.&nbsp;Indenting the <tt class="function">buildConnectionString</tt> Function
            </h3><pre class="programlisting"><span class='pykeyword'>
def</span> buildConnectionString(params):
    <span class='pystring'>"""Build a connection string from a dictionary of parameters.

    Returns string."""</span>
    <span class='pykeyword'>return</span> <span class='pystring'>";"</span>.join([<span class='pystring'>"%s=%s"</span> % (k, v) <span class='pykeyword'>for</span> k, v <span class='pykeyword'>in</span> params.items()])</pre></div>
         <p>Code blocks are defined by their indentation.  By "code block", I mean functions, <tt class="literal">if</tt> statements, <tt class="literal">for</tt> loops, <tt class="literal">while</tt> loops, and so forth.  Indenting starts a block and unindenting ends it.  There are no explicit braces, brackets, or keywords.
             This means that whitespace is significant, and must be consistent.  In this example, the function code (including the <tt class="literal">doc string</tt>) is indented four spaces.  It doesn't need to be four spaces, it just needs to be consistent.  The first line that is not
            indented is outside the function.
         </p>
         <p><a href="indenting_code.html#odbchelper.indenting.if" title="Example&nbsp;2.6.&nbsp;if Statements">Example&nbsp;2.6, &#8220;if Statements&#8221;</a> shows an example of code indentation with <tt class="literal">if</tt> statements.
         </p>
         <div class="example"><a name="odbchelper.indenting.if"></a><h3 class="title">Example&nbsp;2.6.&nbsp;<tt class="literal">if</tt> Statements
            </h3><pre class="programlisting"><span class='pykeyword'>
def</span> fib(n):                   <a name="odbchelper.indenting.2.1"></a><img src="../images/callouts/1.png" alt="1" border="0" width="12" height="12">
    <span class='pykeyword'>print</span> <span class='pystring'>'n ='</span>, n            <a name="odbchelper.indenting.2.2"></a><img src="../images/callouts/2.png" alt="2" border="0" width="12" height="12">
    <span class='pykeyword'>if</span> n &gt; 1:                 <a name="odbchelper.indenting.2.3"></a><img src="../images/callouts/3.png" alt="3" border="0" width="12" height="12">
        <span class='pykeyword'>return</span> n * fib(n - 1)
    <span class='pykeyword'>else</span>:                     <a name="odbchelper.indenting.2.4"></a><img src="../images/callouts/4.png" alt="4" border="0" width="12" height="12">
        <span class='pykeyword'>print</span> <span class='pystring'>'end of the line'</span>
        <span class='pykeyword'>return</span> 1
</pre><div class="calloutlist">
               <table border="0" summary="Callout list">
                  <tr>
                     <td width="12" valign="top" align="left"><a href="#odbchelper.indenting.2.1"><img src="../images/callouts/1.png" alt="1" border="0" width="12" height="12"></a> 
                     </td>
                     <td valign="top" align="left">This is a function named <tt class="function">fib</tt> that takes one argument, <tt class="varname">n</tt>.  All the code within the function is indented.
                     </td>
                  </tr>
                  <tr>
                     <td width="12" valign="top" align="left"><a href="#odbchelper.indenting.2.2"><img src="../images/callouts/2.png" alt="2" border="0" width="12" height="12"></a> 
                     </td>
                     <td valign="top" align="left">Printing to the screen is very easy in <span class="application">Python</span>, just use <tt class="function">print</tt>.  <tt class="function">print</tt> statements can take any data type, including strings, integers, and other native types like dictionaries and lists that you'll
                        learn about in the next chapter.  You can even mix and match to print several things on one line by using a comma-separated
                        list of values.  Each value is printed on the same line, separated by spaces (the commas don't print).  So when <tt class="function">fib</tt> is called with <tt class="literal">5</tt>, this will print "n = 5".
                     </td>
                  </tr>
                  <tr>
                     <td width="12" valign="top" align="left"><a href="#odbchelper.indenting.2.3"><img src="../images/callouts/3.png" alt="3" border="0" width="12" height="12"></a> 
                     </td>
                     <td valign="top" align="left"><tt class="literal">if</tt> statements are a type of code block.  If the <tt class="literal">if</tt> expression evaluates to true, the indented block is executed, otherwise it falls to the <tt class="literal">else</tt> block.
                     </td>
                  </tr>
                  <tr>
                     <td width="12" valign="top" align="left"><a href="#odbchelper.indenting.2.4"><img src="../images/callouts/4.png" alt="4" border="0" width="12" height="12"></a> 
                     </td>
                     <td valign="top" align="left">Of course <tt class="literal">if</tt> and <tt class="literal">else</tt> blocks can contain multiple lines, as long as they are all indented the same amount.  This <tt class="literal">else</tt> block has two lines of code in it.  There is no other special syntax for multi-line code blocks.  Just indent and get on
                        with your life.
                     </td>
                  </tr>
               </table>
            </div>
         </div>
         <p>After some initial protests and several snide analogies to <span class="application">Fortran</span>, you will make peace with this and start seeing its benefits.  One major benefit is that all <span class="application">Python</span> programs look similar, since indentation is a language requirement and not a matter of style.  This makes it easier to read
            and understand other people's <span class="application">Python</span> code.
         </p><a name="compare.lineend.java"></a><table class="note" border="0" summary="">
            <tr>
               <td rowspan="2" align="center" valign="top" width="1%"><img src="../images/note.png" alt="Note" title="" width="24" height="24"></td>
            </tr>
            <tr>
               <td colspan="2" align="left" valign="top" width="99%"><span class="application">Python</span> uses carriage returns to separate statements and a colon and indentation to separate code blocks.  <span class="application"><span class="acronym">C++</span></span> and <span class="application">Java</span> use semicolons to separate statements and curly braces to separate code blocks.
               </td>
            </tr>
         </table>
         <div class="furtherreading">
            <h3>Further Reading on Code Indentation</h3>
            <ul>
               <li><a href="http://www.python.org/doc/current/ref/"><i class="citetitle"><span class="application">Python</span> Reference Manual</i></a> discusses cross-platform indentation issues and <a href="http://www.python.org/doc/current/ref/indentation.html">shows various indentation errors</a>.
               </li>
               <li><a href="http://www.python.org/doc/essays/styleguide.html"><i class="citetitle"><span class="application">Python</span> Style Guide</i></a> discusses good indentation style.
               </li>
            </ul>
         </div>
      </div>
      <table class="Footer" width="100%" border="0" cellpadding="0" cellspacing="0" summary="">
         <tr>
            <td width="35%" align="left"><br><a class="NavigationArrow" href="everything_is_an_object.html">&lt;&lt;&nbsp;Everything Is an Object</a></td>
            <td width="30%" align="center"><br>&nbsp;<span class="divider">|</span>&nbsp;<a href="index.html#odbchelper.divein" title="2.1.&nbsp;Diving in">1</a> <span class="divider">|</span> <a href="declaring_functions.html" title="2.2.&nbsp;Declaring Functions">2</a> <span class="divider">|</span> <a href="documenting_functions.html" title="2.3.&nbsp;Documenting Functions">3</a> <span class="divider">|</span> <a href="everything_is_an_object.html" title="2.4.&nbsp;Everything Is an Object">4</a> <span class="divider">|</span> <span class="thispage">5</span> <span class="divider">|</span> <a href="testing_modules.html" title="2.6.&nbsp;Testing Modules">6</a>&nbsp;<span class="divider">|</span>&nbsp;
            </td>
            <td width="35%" align="right"><br><a class="NavigationArrow" href="testing_modules.html">Testing Modules&nbsp;&gt;&gt;</a></td>
         </tr>
         <tr>
            <td colspan="3"><br></td>
         </tr>
      </table>
      <div class="Footer">
         <p class="copyright">Copyright &copy; 2000, 2001, 2002, 2003, 2004 <a href="mailto:mark@diveintopython.org">Mark Pilgrim</a></p>
      </div>
   </body>
</html>

APT Browse - Built by Thomas Orozco.