CSCI 110, Spring 2011

Review sheet for 1st midterm

The following topics have been covered in the first part of the course. Each of the following topics may appear on the exam.

1.  Introduction to Computer Science
	Imperative vs. Declarative knowledge
	Abstraction (Black box abstraction, Layers of Abstraction)
	Modularity
	Problem solving: Divide and conquer
	Machine language vs. High level languages (Compiler)
	Programming Life Cycle
	Definition of an Algorithm
2.  Python programs
	General form of Python program
	Input and Output (print, input() and raw_input())
	Variables
		Rules for naming variables
		Assigning values to variables
	Data types (integer, long integer, floating point, string)
	Arithmetic expressions (including integer division)
	Strings
	Classes and objects
		Object properties
		Object methods		
3.  Conditional Statements
	Decision Trees
	General form of conditional statement
	Using if ... elif ... else
	Nested conditionals
	Logical Expressions
		Relational operators (<, >, etc.)
		Logical operators (and, or, not)
4.  Using Turtles to draw
	Naming a Turtle object
	Using Turtle methods:
		forward(distance)
		backward(distance)
		left(angle)
		right(angle)
		up( )
		down( )
		goto(x, y)
		circle(radius)
5.  Text manipulation
	Concatenating strings
	Finding the length of a string
	Accessing a character at a given position in the string.
	Accessing a substring of a string	
6.  while loops
	General form of a while loop
	Using a counter in a while loop
	Keeping track of variable values in a loop
	Using compound conditions
7.  Arithmetic expressions
	Precedence rules for +, - , * , /
	Integer division
	The MOD operator for integers
	Formatting floating point numbers
8.  Strings
	Operations with strings
	string methods
9.  Lists
	Accessing values in the list
	Operations with lists
	List methods
10. for loops
	General form of a for loop
	Execution of a for loop
	Using range( ) to create a list of integers
	Writing a count-controlled for loop
	Using for loops with lists
	Changing values of a list with a for loop

Practice Problems
The following problems are intended to help you study for the exam.

1) A boolean is a data type that has a value of True or False.
Given these boolean variables:
x = True, y = False, z = True

What is the value (True/False) of each of the following?

i)  x and (y or z)


ii) (not x) or  (not(y and z))


iii) y or (x and not z)


2)Consider a program that does the following:
Prompt the user to input a number between 0 and 100.
Input the number from the keyboard
If the number is greater than 50 and less than 100  write:
	XX is in the top 50 percent.
where XX refers to the number inputted by the user.
Otherwise, if the number is less than or equal to 50 write:
	XX is in the bottom 50 percent.
Otherwise, write
	Illegal number entered.
	
a) Draw a decision tree for the program.



b) Write a Python program to execute the program




3)  Compute the value of the following expressions:
a)  6 / 3 * 2



b) (17 - 11) / 3 + 3



c) Add parentheses to part b so that the addition is performed
before the division.



d) What is the value of c) ?

4) What is the value of sum after the execution of the following code?

	sum = 0
	for counter in range(1, 5):
		sum = sum + 2 * counter

5) What is the output of the following code fragment (mySentence and partial are both strings)?

	mySentence = "It was a dark and stormy night"
	partial = mySentence[10:13]
	print partial	

• a)

           #Program Error1
           number = raw_input("Please enter a number: ")
           number = number/2.0
           print number
  

  
  

• b)

          #Program Error2
          response = raw_input("Do you like chocolate? ")
          if response == "yes":
              print "Me too!"
          	else:
              	print "That's too bad."
  

  
  

• c)

           #Program Error3
           secret = "csci110"
           response = raw_input("Enter the password: ")
           if response = secret:
           	print "Access granted."
           else:
           	print "Access denied.   
  

  
  

• d)

           #Program Error4
           count = 0
           while count < 10
           	print count
           	count = count + 1
  

7)  Consider the following while loop:
	sum = 0
	count = 5
	while count <= 10:
		sum = sum + count
		count = count + 1

a) Fill in the following table for the values of count and sum each time through the loop (there may be more rows than you need in the table):

b)Write a for loop that does the equivalent of the above loop.

  8) Consider the following Python code:

        sum = 0
        for i in range(1, 5):
              sum = sum + i
        print sum

  9) Fill in the necessary code to fill in the depositList array with deposit amounts entered by the user. You should keep track of the sum of all the deposits made, so that the print statement at the end of the program makes sense. You can assume there are exactly 1000 deposits made.

#Program deposit.py
depositList = [ ]
sum = 0
#your code goes here













print "The sum of the deposits: $%6.2f"% sum