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<h3 class="section">Conditionals with Omitted Operands</h3>



   <p>The middle operand in a conditional expression may be omitted.  Then

if the first operand is nonzero, its value is the value of the conditional

expression.



   <p>Therefore, the expression



<pre class="example">     x ? : y

     </pre>



<p>has the value of <code>x</code> if that is nonzero; otherwise, the value of

<code>y</code>.



   <p>This example is perfectly equivalent to



<pre class="example">     x ? x : y

     </pre>



<p>In this simple case, the ability to omit the middle operand is not

especially useful.  When it becomes useful is when the first operand does,

or may (if it is a macro argument), contain a side effect.  Then repeating

the operand in the middle would perform the side effect twice.  Omitting

the middle operand uses the value already computed without the undesirable

effects of recomputing it.



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