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  68. <a name="Misnesting-1"></a>
  69. <h4 class="subsection">3.10.1 Misnesting</h4>
  70. <p>When a macro is called with arguments, the arguments are substituted
  71. into the macro body and the result is checked, together with the rest of
  72. the input file, for more macro calls. It is possible to piece together
  73. a macro call coming partially from the macro body and partially from the
  74. arguments. For example,
  75. </p>
  76. <div class="smallexample">
  77. <pre class="smallexample">#define twice(x) (2*(x))
  78. #define call_with_1(x) x(1)
  79. call_with_1 (twice)
  80. &rarr; twice(1)
  81. &rarr; (2*(1))
  82. </pre></div>
  83. <p>Macro definitions do not have to have balanced parentheses. By writing
  84. an unbalanced open parenthesis in a macro body, it is possible to create
  85. a macro call that begins inside the macro body but ends outside of it.
  86. For example,
  87. </p>
  88. <div class="smallexample">
  89. <pre class="smallexample">#define strange(file) fprintf (file, &quot;%s %d&quot;,
  90. &hellip;
  91. strange(stderr) p, 35)
  92. &rarr; fprintf (stderr, &quot;%s %d&quot;, p, 35)
  93. </pre></div>
  94. <p>The ability to piece together a macro call can be useful, but the use of
  95. unbalanced open parentheses in a macro body is just confusing, and
  96. should be avoided.
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