Page - 108 - in Programming for Computations – Python - A Gentle Introduction to Numerical Simulations with Python 3.6, Volume Second Edition

108 5 SomeMorePythonEssentials between different kinds of exceptions, coding a dedicated response in each case. That can be done in Python,1 and it will also allow us to get back the Ctrl-c functionality thatwehad in the earlierversions. A More Detailed Use of try-except We let the final version of our code (times_tables_4.py) serve as an example of a more refined try-except construction.It is still simple,buthaswhatweneed.Wepresent thisfinalversionin its completeness, before explaining the details. All code changes are still confined to themainpartof theprogram: import numpy as np def ask_user(a, b): """Get answer from user: a*b = ?""" question = ’{:d} * {:d} = ’.format(a, b) answer = int(input(question)) return answer def points(a, b, answer_given): """Check answer. Correct answer gives 1 point, else zero""" true_answer = a*b if answer_given == true_answer: print(’Correct!’) return 1 else: print(’Sorry! Correct answer was: {:d}’.format(true_answer)) return 0 print(’\n*** Welcome to the times tables test! ***\ \n (To stop: ctrl-c)’) N = 10 NN = N*N score = 0 index = list(range(0, NN, 1)) np.random.shuffle(index) # randomize order of integers in index for i in range(0, NN, 1): a = index[i]//N + 1 b = index[i]%N + 1 try: user_answer = ask_user(a, b) except KeyboardInterrupt: print(’\nOk, you want to stop!’) break except ValueError: print(’You must give a valid number!’) continue # jump to next loop iteration score = score + points(a, b, user_answer) print(’Your score is now: {:d}’.format(score)) print(’\nFinished! \nYour final score: {:d} (max: {:d})’\ .format(score, N*N)) 1 https://docs.python.org/3/tutorial/errors.html.