CSC231m Sample MidTerm

1
CSC-231m Sample Mid-Term

• Questions From Past Mid-Terms
• Point Values
• Answers

2
Todays Topics

• Sample questions from a previous test. Since this
  is the first quarter under MATLAB, these were
  translated from Fortran and C.
• Desired or expected answers to those questions.

3
Notes on Semantics

• Unless otherwise stated, it is unnecessary to put
  statements in IF, FOR, or WHILE constructs.
  is sufficient, or stuff goes here.
• If a question includes, and something else
  otherwise, it means you need an ELSE or an
  OTHERWISE statement.
• If a question about logical expressions includes
  the wording, if this is true and that is also
  true, it means you need an AND ().
• Conversely, if it says or , you need an OR
  ().
• In a loop question, if there are three
  quantities, its a FOR loop. If there is only one
  quantity, its a WHILE loop.

4
Variable Declaration

• 5 points
• Declare one floating point variable fNumberOne
  and one integer variable iNumberTwo and
  initialize them to 12.34 and 567 respectively.
• Desired answer
• fNumberOne 12.34
• iNumberTwo 567

5
Constant Declaration

• 5 Points
• Declare a floating constant called fSEED which is
  equal to 123.45.
• Desired answer
• fSEED 123.45

6
Prompt and Input

• 5 Points
• Write statements that prompt a user to enter
  his/her year of birth, and input the number as an
  integer called iBirth.
• Two possible answers
• disp (Enter your year of birth )
• iBirth input ()
• Or
• iBirth input (Enter your year of birth )
• not required in either case.

7
Equation Development

• 5 Points
• Using fEnergy, fMass, and fLIGHTSPEED, write
  Einsteins famous equation EMc² in proper
  MATLAB.
• Two possible answers, the first one is the
  preferred one
• fEnergy fMass fLIGHTSPEED 2.0
• Or
• fEnergy fMass fLIGHTSPEED fLIGHTSPEED

8
Simple IF Structure

• 5 Points
• Write the significant lines of an IF structure
  that will be executed if iYear is not equal to
  2000.
• You only need TWO statements
• if (iYear 2000)
• end

9
Loop, Counter-Controlled

• 5 Points
• Write the significant lines of a loop in which
  iLoop is initially set to 100, does not exceed
  iMaxVal, and has a step size of 25.
• You only need TWO statements
• for iLoop 100 25 iMaxVal
• end
• (spaces added for clarity and readability)

10
Loop, Event-Controlled

• 5 Points
• Write the significant lines of a loop that
  terminates when iInput is equal to 175.
• Answer
• while (iInput 175)
• end

11
Compound Logical Expression

• 5 Points
• Write the compound logical expression that would
  be true if iInput is greater than 7 and less than
  or equal to 21.
• Answer
• ((iInput gt 7) (iInput lt 21))
• Note the parentheses

12
Program Beginning

• 5 Points
• Other than a header, what are the first lines of
  a program that has integer variables iOne, iTwo,
  and iThree, a float fFour, and a constant fFIVE
  with a value of 5.55?
• Answer
• iOne 0
• iTwo 0
• iThree 0
• fFour 0.0
• fFIVE 5.5

13
Character Strings

• 5 Points
• Declare a character string of Sorry, not a
  winner. called sSorry and then write the line of
  code to display it
• Answer
• sSorry Sorry, not a winner.
• and
• disp (sSorry)

14
Yet Another Loop

• 5 Points
• Write the significant lines of a loop that counts
  from 0 to 100 by 3s using variable iLoop.
• Answer
• for iLoop 0 3 100
• end

15
IF Structure

• 5 Points
• Write the significant lines of an IF construct
  that will do one thing if fVar is less than or
  equal to 42.98 and something else if it is
  greater than 98.25 (dont worry about writing the
  code that goes between or after these).
• Answer
• if (fVar lt 42.98)
• elseif (fVar gt 98.25)
• end

16
More Complex IF Structure

• 10 Points, two parts
• A. Write the significant lines of an IF construct
  that does one thing if cInput is C, another if
  it is S, and something else otherwise
• Answer
• if (cInput C)
• elseif (cInput S)
• else
• end
• B. List two ways to properly handle lowercase
  letters
• cInput upper (cInput) before the construct
• If ((cInput C) (cInput c)) etc.

17
SWITCH-CASE Construct

• 10 Points
• Write the SWITCH-CASE construct for iVar that
  will do one thing if iVar is 0, another if it is
  1, 2, or 3, yet another if it is 4, 5, or 6, and
  something else otherwise
• Answer
• switch (iVar)
• case 0 case 0 is probably OK
• case 1, 2, 3
• case 4, 5, 6
• otherwise
• end

18
Placeholders

• 5 points
• In a sprintf() statement, what do the following
  placeholders mean
• d, s, f, c, 7.2f
• Answer
• d holds the place of an integer
• s holds the place of a string
• f holds the place of a float
• c holds the place of a character
• 7.2f holds 7 places for a float with two decimal
  places

19
Placeholders, Continued

• 7.2f means width of 7 with 2 decimal places,
  width includes sign and decimal point
• - 1 0 0 . 0 0
• - - - - - - -
• 4.3d means width of 4 with minimum of 3 digits
  (leading 0s)
• 0 0 7
• - - - -
• 10s means minimum of 10 spaces, right justified
• H u t c h
• - - - - - - - - - -

20
String Conversion

• 5 Points
• What types of data do these functions convert to
  strings for use in disp()
• num2str(), char(), int2str()
• Answer
• num2str() converts float to string
• char() converts characters to string
• int2str() converts integer to string

21
Todays Lessons

• You should have some idea of what the test will
  be like, and what sorts of answers I am expecting.