title: Trying to find difference in days between user's date of birth and now, in Python
body: <p>I am  learning python(beginner) and have been set a task to write a program to find difference in days between user's date of birth and now, in Python. I know how to work out the time now (datetime.now) and how to ask the user to input something(raw_input). However, these answers are in different formats, so there is no way to subtract one from another. Is there a way of converting them to the same format, or would slicing(not sure if that's the right terminology-so baton[0:3]-the first 4 charcters in the word baton) and then turning into integers,  and then subtracting work. there have been some other answers on stack overflow, using strptime(not sure what this is). However, these posts talk about subtracting two dates that are already in the same format and are known by the program(i.e , no use-input involved). Here are these posts: 
  <strong><a href="https://stackoverflow.com/questions/151199/how-do-i-calculate-number-of-days-betwen-two-dates-using-python">How do I calculate number of days betwen two dates using Python?</a></strong>, <a href="https://stackoverflow.com/questions/2788871/python-date-difference-in-minutes">python date difference in minutes</a> and <a href="https://stackoverflow.com/questions/1345827/how-do-i-find-the-time-difference-between-two-datetime-objects-in-python">How do I find the time difference between two datetime objects in python?</a> 
  I hope that this information is enough that somone may be able to help. I would be really grateful if anyone was able to help me. Thanks!</p>