title: stl::find_if with user search
body: <p>I was wondering if there was a way to use the stl::find_if to search for a user inputted value</p>
  
  <p>I don't know to do that without using any bad conventions(globals) or adding loads of extended code. </p>
  
  <p>For example, if a user inputs a int x for 10, then I want to search an vector of ints</p>
  
  <pre><code>iterator = find_if(begin,end,pred) //but how does pred know the user inputted value?
  </code></pre>