title: Python time difference from string
body: <p>I have a string '16:40' and I would like to calculate the difference in minutes between this string and now. So assuming <em>now</em> is 16:52, then the difference would be 12 minutes.</p>
  
  <p>I have the following code:</p>
  
  <pre><code>import time
  
  tString = '16:40'
  t1 = time.strptime(tString, "%H:%M")
  now = time.time()
  print (now - t1)
  </code></pre>
  
  <p>For which get the following type error:</p>
  
  <pre><code>TypeError: unsupported operand type(s) for -: 'float' and 'time.struct_time'
  </code></pre>
  
  <p>So I'm creating the incorrect type for <em>now</em> - any ideas?!</p>