====== Computer Lab 03, functions, errors and exceptions ======

===== practical work =====

We use the code implemented last week, from [[http://openbookproject.net/thinkcs/python/english3e/|Wentworth2012]] and make it more flexible by encapsulating the core functionality in functions.

**2.14.5** Create a function ''compute_final_amount'' that will have ''P,r,n,t'' as the input parameters. Comment the function appropriately. Make the code robust against dividing by zero runtime problem:

  - Use if-condition to catch the case where the denominator is zero, print an error message (using 'print') and return from the function.
  - Use if-condition to catch the case where the denominator is zero and raise an exception.
  - Handle this exception completely with a "try-except" block, i. e., no if-condition needed.

===== Weekly homework 03 =====
<WRAP center round box 60%>
**time difference** variant of 2.14.7 and 2.14.8. Implement a function ''compute_time_diff(h1,m1,h2,m2)'' that returns two values - hours, minutes - time difference between t2-t1, where the time is expressed in hours and minutes. Expect 24 hours notation. Required file name: ''03_weekly_hw.py''.

Usage:
<code python>
>>> h,m = compute_time_diff(13,20,15,10)
>>> print(h,m)
1 50
</code>
</WRAP>

===== homework =====
<note important>
Solve homework [[courses:be5b33prg:homework:regular:01_right_triangle|01 - Right triangle]] and submit it via Upload system in time! Check the deadline in Upload system.
</note>

  * Read chapters 6,7,8,9 from [[http://openbookproject.net/thinkcs/python/english3e/|Wentworth2012]]. This material is for the next two lectures/labs.