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   9 <title>Chapter 23: Two-Dimensional (and Multidimensional) Arrays</title>
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  15 <H1>Chapter 23: Two-Dimensional (and Multidimensional) Arrays</H1>
  16
  17 <p>C does not have true multidimensional arrays.
  18 However,
  19 because of the generality of C's type system, you can have
  20 <dfn>arrays of arrays</dfn>,
  21 which are almost as good.
  22 (This should not surprise you;
  23 you can have arrays of anything, so why not arrays of arrays?)
  24 </p><p>We'll use two-dimensional arrays as examples in this section,
  25 although the techniques can
  26 be extended to three or
  27 more dimensions.
  28 Here is a two-dimensional array:
  29 <pre>
  30         int a2[5][7];
  31 </pre>
  32 Formally, <TT>a2</TT> is an array of 5 elements, each of which is
  33 an array of 7 <TT>int</TT>s.
  34 (We usually think of it as having 5 rows and 7 columns,
  35 although this interpretation is not mandatory.)
  36 </p><p>Just as we declared a two-dimensional array using two pairs of brackets,
  37 we access its individual elements using two pairs of brackets:
  38 <pre>
  39         int i, j;
  40         for(i = 0; i &lt; 5; i++)
  41                 {
  42                 for(j = 0; j &lt; 7; j++)
  43                         a2[i][j] = 0;
  44                 }
  45 </pre>
  46 Make sure that you remember to put each subscript in its own,
  47 correct pair of brackets.
  48 Neither
  49 <pre>
  50         int a2[5, 7];           /* XXX WRONG */
  51 </pre>
  52 nor
  53 <pre>
  54         a2[i, j] = 0;           /* XXX WRONG */
  55 </pre>
  56 nor
  57 <pre>
  58         a2[j][i] = 0;           /* XXX WRONG */
  59 </pre>
  60 would do anything remotely like what you wanted.
  61 </p><p><a href="sx9a.html" rel=subdocument>23.1: Multidimensional Arrays and Functions</a></p>
  62 <p><a href="sx9b.html" rel=subdocument>23.2: Dynamically Allocating Multidimensional Arrays</a></p>
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