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7 Tips and Techniques Sneaking in Extra Material Daniel Joyce Department of Computing Sciences Villanova University Villanova PA USA Introduction Did you ever wish you could sneak some extra material into a course but it just doesn t fit with the syllabus and there s not enough time to add another unit to an already crowded calendar? In this Tips and Techniques I described how I snuck some computing history into an introductory programming course. 2. Context When I found myself teaching an introductory programming course for the first time in many years in the Fall of 1999 I decided to try to include some exposure to computing history as part of the course. Part of the impetus for this mini-project was the fact that the first programming assignment that I gave to the class involved programs to encode and decode secret messages. I was struck by the fact that one of the earliest uses of computers during World War 2 was related to this first assignment. So I decided to tie the description of the assignment to computing history. Once I got started it became a challenge to also tie later assignments to some aspect of computing history. All together I linked 7 of my 10 programming assignments to computing history and/or some aspect of the modern use of computers. Hopefully this provided the students with a realistic context for the toy programs they were developing. 3. Application My first programming assignment required the students to write two programs one to encode a string so that it is difficult to read and one to decode the string. The assignment description was posted on the web and began as follows: The early development of computers was hastened by the need for computing power during World War 2 in England computing pioneer/genius Alan Turing continued his work on cryptanalysis (coding and decoding messages) work which helped the Allies immensely during the war. Read about this chapter (and others) of Turing's interesting life: Alan Turing - A short biography. The last five words of the above description were a web link to an interesting essay about the life of Turing. The problem introduction was of course followed by a description of the required program functionality along with some sample input and output. So the pattern was set. I would give an assignment description write a little bit about how it ties into some aspect of computing and provide a link to a related web site for the curious. Here is a list of the assignments that I managed to present following this pattern: 1. Encoding and decoding secret messages were connected to Alan Turing s life and work. 2. Creating an applet to draw art in its window was with a bit of a stretch related to Donald Knuth and his series titled The Art of Computer Programming. Hey I never claimed the connections between the assignments and history would be perfect! 3. A program that holds a conversation with its user is more clearly related to Joseph Weizenbaum s "Turing Test" program Eliza. 4. For an exercise in repetition I noted that it was the repetition inherent in engineering work that prompted pioneers like the German engineer Conrad Zuse to search for mechanical aids. 5. Implementing the dice game Pig was related to the relationship between computers and games. 6. Running multiple simulations of the Pig game and collecting and presenting information about the results was tied to the use of computers for simulations and modeling. 7. Extending the previous assignment to present the information as a histogram was tied to the use of computers for information visualization. The assignment descriptions are available at 4. Results If nothing else I had some fun making the assignments and tying them to computing history. It would be fair to ask if the students actually followed the links and read the historical information. Based on the results of a history related surprise bonus question that I included on the first test I would have to report that the students did not seem to absorb much of the historical information during the first third of the semester. But the good news is that they did much better on the history related surprise bonus questions on the remaining tests! Imagine that.

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19 $0+ ()'? # 5& KK )! 0 Chapter 4 C++ Problem Solving with if statements 0 X>0? false negative true 1 positive Chapter 4 C++ Where is my animal? Write a program that uses nested if statements so the user can play a guessing game which of 4 animals the computer is thinking of. For example the program asks if the animal has 4 legs then if it can bark. The output should print the answer and tell the user if she guessed correctly. Scales? 4 legs? Bark? C++ Chapter 4 C++ More about if statements if/else statements review These 2 statements can be replaced if (x>0) cout << positive ; if (x<=0) cout << negative ; by one if/else statement: if (x>0) cout << positive ; else cout << negative ; This is bi-directional program flow or branching. and or not Chapter 4 C++ More about if statements &&! Logical Operators if ((age >12) && (age<19)) cout<< teenager ; if ((letter = Y ) (letter = y )) cout<< yes continue ; if (!((age>12) && (age<19)) cout << not a teenager ; Chapter 4 C++ Compound if statements if (condition) { multiple statements} else {multiple statements} If (temp<=40) {cout<< Wear a coat today. ; cout<< It is cold. ;} else {cout<< Do you wear a sweater (S) or blazer (B)? ; cin<< answer; If (answer == B ) cout << Use your blazer. //nested if else cout << Wear your sweater. cout<< It is cool but warming up. ; } Chapter 4 C++ if/else without ladder if (stones >1) cout<< large ; else if ((stones>0.1) && (stones <=1)) cout << medium ; if (stones < 0.1) cout << small ; large > 1 cm medium.1 to1 cm small < 0.1 cm clam fish cat dog Chapter 4 C++ if / else ladder Multi-directional flow Simplified ladder form: if (stones >1) cout<< large ; else if (stones>0.1) cout << medium ; else cout << small ; extra comparisons (boolean statements) removed Chapter 4 C++ if rewritten as ladder sample if (grade>=90) cout <<"A"; if (grade>=80) && (grade <90) cout <<"B"; if (grade>=70) && (grade <80) cout <<"C"; if (grade>=60) && (grade <70) cout <<"D"; if (grade <60) cout <<"F"; if (grade>=90) cout <<"A"; //must have a semicolon before the else else if (grade>=80) // eliminate && (grade <90) cout <<"B"; else if (grade>=70) // eliminate && (grade <80) cout <<"C"; else if (grade>=60) // eliminate && (grade <70) cout <<"D"; else // eliminate (grade <60) cout <<"F"; Chapter 4 C++ if problem Review 8 Write a program that asks the user for the number of strokes on one hole of a par 5 golf game then displays a message according to the list: 1 Hole in one! 2 Double-Eagle 3 Eagle 4 Birdie 5 Par 6 Bogey 7 Triple- Bogey 8 Double-Bogey 9 Or more = Disaster Chapter 4 C++ if problem C++ Review 11 Write a program that asks the user for the length width and height of a package and displays reject if any dimension is C++ greater than 10 cm and Accept if all the dimensions are less than or equal to 10 cm. Like a sieve stops at the right step of the ladder Chapter 4 C++ if problem Review 9 Find logic errors in this code. It should display one message or any value of Height. Rewrite this using an if/else ladder if (Height <150) cout<< short <<endl; if ((Height>150) && (Height<175)) cout << medium <<endl; if (Height>175) cout << tall <<endl; C++ BC

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Unit 7. 'while' Loops

Unit 7. 'while' Loops 1 Unit 7 'while' Loops 2 Control Structures We need ways of making decisions in our program To repeat code until we want it to stop To only execute certain code if a condition is true To execute one segment