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   9 <title>7.1 Assignment Operators</title>
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  15 <H2>7.1 Assignment Operators</H2>
  16
  17 <p>[This section corresponds to K&amp;R Sec. 2.10]
  18 </p><p>The first and more general way is that any time you have the
  19 pattern
  20 <pre>
  21         <I>v</I> = <I>v</I> <I>op</I> <I>e</I>
  22 </pre>
  23 where <I>v</I> is any variable
  24 (or anything like <TT>a[i]</TT>),
  25 <I>op</I> is any of the binary arithmetic operators we've seen so far,
  26
  27 and <I>e</I> is any expression,
  28 you can replace it with the simplified
  29 <pre>
  30         <I>v</I> <I>op</I>= <I>e</I>
  31 </pre>
  32 For example, you can replace the expressions
  33 <pre>
  34         i = i + 1
  35         j = j - 10
  36         k = k * (n + 1)
  37         a[i] = a[i] / b
  38 </pre>
  39 with
  40 <pre>
  41         i += 1
  42         j -= 10
  43         k *= n + 1
  44         a[i] /= b
  45 </pre>
  46 </p><p>In an example in a previous chapter,
  47 we used the assignment
  48 <pre>
  49         a[d1 + d2] = a[d1 + d2] + 1;
  50 </pre>
  51 to count the rolls of a pair of dice.
  52 Using <TT>+=</TT>, we could simplify this expression to
  53 <pre>
  54         a[d1 + d2] += 1;
  55 </pre>
  56 </p><p>As these examples show,
  57 you can
  58 use the ``op='' form
  59 with any of the arithmetic operators
  60 (and with several other operators that we haven't seen yet).
  61 The expression, <I>e</I>,
  62 does not have to be the constant 1;
  63 it can be any expression.
  64 You don't always need as many explicit parentheses
  65 when using the <I>op</I><TT>=</TT> operators:
  66 the expression
  67 <pre>
  68         k *= n + 1
  69 </pre>
  70 is interpreted as
  71 <pre>
  72         k = k * (n + 1)
  73 </pre>
  74
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  84 This page by <a href="http://www.eskimo.com/~scs/">Steve Summit</a>
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