lang/C/the.ansi.c.programming.language/notes.accompany.ansi.c/sx6h.html

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   9 <title>section 3.8: Goto and Labels</title>
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  15 <H2>section 3.8: Goto and Labels</H2>
  16
  17 pages 65-66
  18 <p>A tremendous amount of impassioned debate surrounds the lowly
  19 <TT>goto</TT> statement, which exists in many languages.
  20 Some people say that <TT>goto</TT>s are fine;
  21 others say that they must <strong>never</strong> be used.
  22 You should definitely shy away from <TT>goto</TT>s,
  23 but don't be dogmatic about it;
  24 some day,
  25 you'll find yourself writing some screwy piece of code where
  26 trying to avoid a <TT>goto</TT>
  27 (by introducing extra tests or Boolean control variables)
  28 would only make things worse.
  29 </p><p></p><p>page 66
  30 </p><p>When you find yourself writing several nested loops
  31 in order to search for something,
  32 such that you would need to use a <TT>goto</TT>
  33 to break out of all of them
  34 when you do find what you're looking for,
  35 it's often an excellent idea to
  36 move
  37 the search code out into a separate function.
  38 Doing so
  39 can make both the ``found'' and ``not found'' cases
  40 easier to handle.
  41 Here's a slight variation on the example in the middle of page 66,
  42 written as a function:
  43 <pre>   /* return i such that a[i] == b[j] for some j, or -1 if none */
  44 <br>
  45 <br>
  46         int findequal(int a[], int na, int b[], int nb)
  47         {
  48                 int i, j;
  49 <br>
  50 <br>
  51                 for(i = 0; i &lt; na; i++) {
  52                         for(j = 0; j &lt; nb; j++) {
  53                                 if(a[i] == b[j])
  54                                         return i;
  55                         }
  56                 }
  57 <br>
  58 <br>
  59                 return -1;
  60         }
  61 </pre>This function can then be called as
  62 <pre>   i = findequal(a, na, b, nb);
  63         if(i == -1)
  64                 /* didn't find any common element */
  65         else    /* got one */
  66 </pre>(The only disadvantage here is that it's trickier to return
  67 <TT>i</TT> and <TT>j</TT> if we need them both.)
  68 </p><hr>
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  77 This page by <a href="http://www.eskimo.com/~scs/">Steve Summit</a>
  78 // <a href="copyright.html">Copyright</a> 1995, 1996
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