Midterm Review

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Midterm Review
Feb. 26, 2008
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Test Logistics

• Take-home part of the exam will be available at
  roughly 530pm, Tuesday, Feb. 26
• In-class exam will be during Thursday's lecture
  time
• Both parts of the exam will be due at 515pm on
  Thursday (on Oncourse)?
• Finish take-home part before the in-class part
  starts!
• Submit both parts of the test together

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Test Logistics

• If you have a laptop, then come here for the
  in-class exam
• Charge your battery beforehand!
• Bring a power strip!
• If you don't have a laptop, then go to room 221
  in the Student Building (SB)?

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Test Rules

• All notes, books, and previous code are allowed
  to be used on both parts of the exam
• You may not discuss any of the exam problems with
  anyone else
• You may not copy source code from the Internet

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Preparation Tips
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1. Finish ALL Labs

• Make corrections on graded labs
• Learn from your previous mistakes...don't repeat
  them
• Go back and do lab programs you didn't do
• You must know how to complete the labs
• Nothing else will have as large an effect on your
  exam grade

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2. Re-Do Labs from Scratch

• Don't look at any of your old code
• Don't look at any sample source code
• Don't even look at the text book
• If you can work out all labs from scratch
• You will almost surely get an A

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3. Reading vs. Coding

• Reading is great for understanding theory and
  concepts
• The exam tests your ability to program
• My advice
• Spend your study time programming
• Reading is great if you are confident that you
  can program all the labs and homeworks from
  scratch

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4. Have Examples Ready

• There are a lot of tricky things to learn about
  programming
• strings
• loops
• if-else, switch
• Have a simplified set of examples that show how
  to do each of these tasks

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5. Organize Your Old Code

• The exam is going to be challenging and it's
  going to take time
• Many students work until the last minute
• Don't waste time looking for old source code
  files, sample code, examples, notes
• Test out code from lecture slides and see what it
  does and how it works
• Change it around and see what happens

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6. Concentrate on the Harder Topics

• Nearly every lab and homework built on those that
  came before
• The exam is absolutely cumulative!
• If you're re-working the labs
• Start at the last lab and work backwards
• If you can do strings, loops, and if-else/switch
  logic, then you won't have any problem with
  printf and scanf

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7. Do the Easier Program First

• Quickly read both problems on the test
• Identify which you think will be easier or faster
• Finish that one completely first!
• Don't lose points for stuff you know because you
  ran out of time

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8. Don't Give Up!

• Absolutely do not leave any problems blank!
• You'll get a 0 for anything that is blank or not
  submitted
• Don't randomly copy code just so it isn't blank
• If you're really stumped, write the solution out
  in English or pseudocode
• Write out any code that you can (printf, scanf,
  variables you know you will need, etc.)?

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9. Ask for Clarification

• If you're not sure about a program requirement,
  then ask for clarification
• We can help you better understand what the
  problem is, but we can't really help you on the
  solution (in a general or specific way)?

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10. Start Take-Home Early

• Even if you think the take-home programs won't
  take you very long, start them early anyway
• Start them tonight! Think how happy you would be
  if you were all done by tomorrow morning!
• The amount of time it takes to write a program
  correctly is very difficult to predict

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11. Sample Source Code

• Passwords
• spider
• zebra
• turtle
• elephant
• porcupine
• gorilla
• giraffe
• panther

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Topics
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printf, scanf

• Know when to use d, 5d, f, g, .2f, 5.3f,
  etc.
• Know when to use an '' in a scanf statement
• scanf( s, myString )
• What kind of string will this NOT get?

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scanf Return Value
int age 0 int numberScanned 0 printf(
Please enter your age ) numberScanned
scanf( d, age ) if( numberScanned 1
)? printf( Age d successfully scanned.\n,
age ) else printf( Illegal input\n
)
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scanf Return Value
numberScanned will be 1 if the scanf succeeded
and got an integer value for age. Otherwise,
numberScanned will be 0.
int age 0 int numberScanned 0 printf(
Please enter your age ) numberScanned
scanf( d, age ) if( numberScanned 1
)? printf( Age d successfully scanned.\n,
age ) else printf( Illegal input\n
)
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Using include and define

• include other libraries of functions
• stdio.h
• stlib.h
• ctype.h
• string.h
• math.h
• define constants in your program
• define MaxStringLength 64

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Simple Variables

• int, float, char, etc.
• Assignment operator
• x 15
• x y 10
• x z
• Using integers as counters in loops
• Built-in in for loops
• Manually added for while/do-while loops

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Type Casting

• int / int has a problem with loss of precision
  (we lose the decimal part)?
• 2 / 5 yields the value of 0
• We cast an int into a float to maintain full
  accuracy
• (float) 2 / 5 yields the value of .4

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Return Values

• A program ending normally with no errors returns
  0
• return( 0 )
• A program that encounters an error (e.g. bad user
  input) returns a non-zero error code (using the
  value of 1 is fine)?
• return( 1 )

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strings

• Declaring a new string variable
• char nameMaxStringLength
• char name Tracy
• Scanning and printing a string
• scanf vs. sgets
• Printing a single character
• printf( The third char is c\n, name2 )

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strings

• Changing the value of a character in a string
• name0 'X'
• name5 '\0'
• String functions
• strlen, strncpy, strlcat

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strings

• Looping over characters in a string
• for( i 0 i lt strlen( name ) i )?
• if( namei 'e' )?
• printf( Found an e!\n )

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Escape Characters

• How do you print out newlines and tabs?
• printf( Game\t0ver\n )
• How do you print out double quotes?
• printf( An important word, \rosebud\\n )

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Mathematical Operators

• Basic operators
• , -, , /
• Update operators
• , --, , -, , /
• Difference between and

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Math

• Functions in math.h
• pow, log, floor, ceil, sqrt, sin, cos, etc.
• Remainder operator,
• 5 2 gives you the remainder when you divide 5
  by 2 (answer 1)?
• 8 3 gives you the remainder when you divide 8
  by 3 (answer 2)?

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if-else/switch Statements

• When to use if-else vs. switch
• Comparison operators
• , !, gt, lt, gt, lt
• Combining conditions
• ,

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switch Statements

• switch statements replace long if-else chains
• The value that is checked can be a variable or an
  expression
• switch( myLetter )?
• switch( x 2 )?
• Don't forget the required break statements

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switch Example
char initial ' ' printf( Please enter your
first initial ) scanf( c, initial
) switch( initial )? case 'm' case
'M' printf( We have the same first
initial!\n ) break default printf(
We don't share the same initial\n) break
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switch Example 2
int age 0 printf( Please enter your age
) scanf( d, age ) switch( age 5
)? case 0 printf( Your age is a
multiple of 5!\n ) break default print
f( Your age is NOT a multiple of
5\n) break
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bool Variables

• Boolean variables are declared using the keyword
  bool
• Can hold either value true or the value false,
  nothing more
• include stdbool.h

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Loops

• Since loops are vital in programming, loops will
  be on the midterm extensively
• 3 kinds of loops for, while, do-while
• Know when to use each kind
• Know how to convert between the different kinds
  of loops

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Loops to Know

• Looping through a string, char by char
• Using a for loop is easiest
• Using a do-while loop to keep prompting the user
  for input until correct input is entered
• for loops forwards and backwards
• counting variable initialization
• i 0
• i some other value (e.g. 1)?

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Questions

• Any questions?
• Any examples you want to see?