title: How to use string::find to find either "+" or "-" in one operation
body: <p>I want to find the location of <code>+</code> or <code>-</code> in a complex number , e.g.</p>
  
  <pre><code>x + y*i 
  
  x - y*i
  </code></pre>
  
  <p>Usually , I will do this : </p>
  
  <pre><code>int found = str.find("+");
  if (found != string::npos)
      cout &lt;&lt; "'+' also found at: " &lt;&lt; found &lt;&lt; endl;
  
  
  found = str.find("-");
  if (found != string::npos)
      cout &lt;&lt; "'-' also found at: " &lt;&lt; found &lt;&lt; endl;
  </code></pre>
  
  <p>How can I give <code>find</code> multiple options to find in a single run ? </p>