In-class notes for 03/10/2014

CS 121B (CS1), Spring 2014

• Homework assignment

• Postpone quiz to Friday

• Recurring themes

Submitted questions on assignments and technology

• 10085: led to a fix, thanks! Piazza is safer bet...

• Example of an error when using recursion (double() problem):

      def double(numlist):
  	if numlist == []:
  	    return 0
  	# assert: there is at least one element in numlist
  	else:  
  	    return 2*numlist[0] + double(numlist[1:])
  

• Three forms of the + operator:

  • Add numbers, e.g.,     4 + 2.9 --> 6.9

  • Concatenate strings, e.g.,     "hi + "lo" --> "hilo"

  • Concatenate lists, e.g.,     [1, 'a'] + [2] --> [1, 'a', 2]

Upcoming

• Homework 13

• Read online text: Dictionaries
  submit at least one reading question by 9am before the next class meeting

Submitted questions on readings

• Note: We will omit "L-system" (we have plenty of other applications that are more important for our purposes -- see Recurring themes)

Summary of strings chapter

• Splitting input strings into words; motivation

Recursion

• Problem solving with recursion

• In-class exercises

• Three ways to understand recursion

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