CSCI 110

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    Review sheet for 2nd midterm

    Topics for Exam2:
    This sheet is intended to help you prepare for the second midterm exam in this course. The exam will primarily focus on chapters 2, 3.1-3.2, 4, 8.7 and 9 of the textbook, section 1.8-1.9 of the Python booklet and all the lectures and labs through Tuesday, 4/5/11. However, there will also be some questions from the beginning part of the course so you should review sections 1.1-1.4, 1.6 - 1.7 of the booklet and your notes on Python programming as well. You should study your class notes, handouts, homeworks and labs. Solutions to the homeworks and labs can be found at the course website: http://mathcs.holycross.edu/~csci110.

    The following topics have been covered in the second part of the course. Each of the following topics may appear on the exam. In addition there may be questions on any of the topics from the first part of the course. 

    1.  Functions
	Divide and conquer programming
	Writing function definitions
	Calling a function
	Execution of a function
	Formal and actual parameters
	Returning a value from a function
	
2.  Recursion
	Definition of recursion
	Writing a recursive function (one that calls itself)
	Classic examples of recursion: Fibonacci, Factorial

3.  Writing classes
	Writing a class definition
	Specifying class properties
	Specifying class methods (functions)
	Using self
	The constructor function (__init__( ))
	The __str__( ) function
	Creating an object
	Calling class functions with an object (dot notation)
	
4.  Church-Markov-Turing Hypothesis

5.  Binary representation
	Counting in base 2
	Converting from decimal to base 2 (and back)
	Hexadecimal representation (base 16)
	Integer representation
	     Signed magnitude, One's complement, Two's complement
	Binary arithmetic	
	Floating point representation

6.  Digital Circuits
	Components:
		Logic switches, AND, OR, NOT, NAND, NOR and XOR
	Writing Truth tables for circuit outputs
	Writing logical expressions to describe circuit outputs
	Designing a circuit to compute a logical expression

    Practice Problems
    The following problems are intended to help you study for the exam. Solutions to these problems will be posted on the CSCI 110 website. You should try to solve the problems before looking at the solutions! 

    1)  Given the function definition:
	def Mystery( someVal):
		answer = 0
		if  someVal > 2.0:
			answer =  3.0 * someVal
		else:
			answer =  0.0
		return answer
    What is the value is assigned to x after execution of the following statement? 
    	x = Mystery(2.5)
    2) Consider the following program: 
    	def Demo( theList, answer):
		theList[0] = theList[0]*2
		answer = theList[0] + 3.5

	myList = [20]
	myResult = 4.8
	Demo(myList, myResult)
	print myList
	print myResult
    What is printed out?
    3) a)Write a function, 
    	def sumOfIntegers( n ):
    that returns the sum of all integers from one to n.
    b) Write a Python statement to compute the sum of integers from 1 to 100 using the above function and store the answer in the variable, hundredSum.
    4) What is the output of the following program? 
    	#program: review.py
	import sys
	def reverse(word, n):
		if n < 0:
			print
		else:
			sys.stdout.write(word[n])
			reverse(word, n-1)
	myWord = "back"
	reverse(myWord, len(myWord) -1)
    5) a) Write a class, Student, that has three properties, gradYear, name and gpa.
    The class should hava a constructor function that sets the values of these properties when the object is created.
    The class should have a function, printInfo( ), that prints out the values of the students name, graduation year and GPA.
    b) Write Python code to creat a Student object, setting the name to "Jane Doe", the graduation year to 2010 and the gpa to 3.75. Invoke the printInfo( ) function for this object to print out the student's information.
    6) a) Convert the following numbers to binary representation: 
    
	237

	45

	63
    b) Convert the above numbers to hexadecimal representation
    7) For each of the following numbers, show their representations in each of: signed magnitude, 1's complement and 2's complement: 
    	22

	-31

	-22

	49
    8) Using eight bit numbers, add the following two binary numbers: 
    	01110001
	00011100
    Show your work. Convert the result to decimal.
    9) Draw a circuit that computes the following truth table for inputs a and b and output c:

    abc
    000
    011
    101
    110

    10) Write an expression for the output of the following circuit. Draw a truth table that shows the output for each combination of inputs: