 <pre><code>void *multiply() </code></pre> <p>The values of struct variables <code>a</code> and <code>b</code> are not initialized within this function you should be passing the scanned values in <code>main()</code> to this function as well as <code>divide()</code></p> <p>There is no reason here I see why you are returning <code>void *</code>. Pass parameters by reference or by value.</p>