Visual Basic Games: Prepare for Hangman

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Visual Basic Games Prepare for Hangman

• Questions on Memory
• String operations array operations
• Homework Take practice quiz
• Next week Quiz Show projects

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Memory?

• Questions?
• Show projects to me in lab.

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Hangman

• Computer is the player with the secret word.
• Uses an internal array (word bank) from which
  program randomly picks a word.
• User-interface (game board) includes
• dashes indicating number of letters in hidden
  word
• Alphabet labels to be clicked by player. Note
  this is a modification of the pencil-and-paper
  game for the computer. (You may also look up how
  to use the keyboard)
• Images showing progression of the hanging. (You
  may choose to make your own images, but do this
  after you build the rest of the application.)
• Command button for new game

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Data types

• Most programming languages have the concept of
  data type.
• Systems need data type to determine how much
  space to allocate and how to treat collection of
  bits.
• So far, data types have been Integer, Single,
  Boolean and String
• Note the contents of captions and textboxes are
  strings.

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Strings

• Visual Basic treats strings as a distinct data
  type.
• Some other computer languages implement strings
  as arrays of single characters. Character is the
  data type.
• Some have special characters for the end of
  string.
• Visual Basic has special functions for string
  handling
• Len(stringname)
• Mid(stringname, position, length)
• Left(stringname,length)
• Right(stringname,length)

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Indexing

• Control arrays (arrays of elements on the form)
  are indexed from 0 to n-1 when n is the number of
  elements
• New elements can be dynamically loaded (loaded
  during runtime)
• Internal arrays (arrays of internal variables)
  can have any index bounds. Can also have more
  than one dimension
• Individual characters in strings are indexed 1 to
  n where n Len(Stringname)
• Index errors are common! Visual Basic will catch
  a runtime index out of bounds error.
• Alternative?

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Examples

• dim strName as String
• strName"abcde"
• What is
• Len(strName)
• Mid(strName,2,3)
• Left(strName,4)
• Right(strName,3)

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Constants

• Also termed named constants for variables that
  do not change
• Use in place of actual numbers (or strings) for
  readability of code and for easing changing of
  code.
• Const strAlpha as String _ abcdefghijklmnopqrst
  uvwxyz
• Const conNumw as Integer 5 words in word bank
• Const conHung as Integer 5 length of hanging
• Const conLeftc as Integer 270 twips

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Control array for alphabet

• Each label is a single letter.
• First letter set at design time. Other letters
  generated during execution time (dynamically)
  using Load statement.
• For I 1 to 25
• Load lblAlphabet(I)
• lblAlphabet(I).Left lblAlphabet(I).Left I
  conLeftc
• lblAlphabet(I).Caption Mid(strAlpha,I1,1)
• lblAlphabet(I).Visible True
• Next I
• Labels made invisible after player clicks them.

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Setting up choices for computer

• strWordBank is name we chose for an array of
  strings.
• Define user-defined procedure setupwordbank()
• ReDim strWordBank(conNumw)
• strWordBank(0) movie
• strWordBank(1) quixotic
• You can certainly chose your own words. But do
  make sure you have word with double letters to
  test logic (maybe even two letter or one letter
  words???)

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Player move lblAlphabet_Click(Index)

• Player clicks particular letter of alphabet. Is
  this in the hidden word?
• Index indicates which specific label was clicked.
• strWordBank(intChoice) is the particular word
  chosen by the computer
• Is lblAlphabet(Index).Caption equal to any letter
  in strWordBank(intChoice) ?

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How to check if players pick is in the chosen
word

• intLength has been set to length of the chosen
  word
• Use For/Next loop
• with I going from 1 to intLength
• Compare the players pick with each letter in the
  chosen word.
• In the loop,
• strLetter Mid(strWordBank(intChoice),i,1)

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Code for new display

• If the players guess is good, you need to
  reconstruct the word display
• lblHiddenPlace.Caption _ Left(LblHiddenPlace.Capt
  ion,i-1) _
• strLetter _
• Right(lblHiddenPlace.Caption,intlength-i)
• Remember to put in underscore _ if any line of
  code goes over to the next line.

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Continue checking letters

• Your code needs to keep going for the rest of the
  word whether there was a hit or not.
• However, if you get a hit, you set a Boolean so
  as to NOT proceed with the hanging. You also
  increment intNumPicked. If and when this equals
  intLength, the player wins!
• If you advance the hanging, you need to check if
  it is complete. In this case, the player loses!

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Events

• If the player clicks on a visible label, then the
  label Click event handler is invoked.
• If the player clicks directly on the Form or
  where there is an invisible label, the Form_Click
  event handler is invoked.
• In this case, use MsgBox to give feedback to
  player to try again.

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Initialization

• Form_Load sets up lblAlphabet and calls
  user-defined procedures to set up word bank, set
  new game and choose a new word.
• cmdNewWord calls same routines and also sets the
  Visible property of all the lblAlphabet labels to
  True.

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Homework

• (Complete and show Memory)
• Complete and show Hangman project
• Do on-line practice quiz in order to prepare for
  next week, including sending or posting
  questions.
• Quiz is in classroom (not lab) on 3/4
• (Catchup) and Hangman, anything else due 3/6.