There are ain

1
Lecture 9

• There are aint no way to find out why a snorer
• cant hear himself snore
• Mark Twain, Western koan

2
Lecture 8 review

• for-loops
• nested for-loops

3
Can the for-loops be even cooler?

• Hmm. What about looping over characters What if
  we want to go through alphabet and do something?

4
Ordinal types

• Ordinal types are the ones which are countable
• For example integers, characters, boolean
• but not reals.

5
Ordinal types

• Orinal types have concept of
• successor and predecessor
• succ( A ) is (major wow) B
• pred( A ) is (major MOM!) _at_
• Lets see more detailed example

6
Ordinal types

• succ( pred( A ) )
• chr( ord( A ) )
• succ( TRUE )
• pred( TRUE )

7
Characters as loop counter!

• Running through the alphabet
• for cMyChar a to z do
• Lets see examples

8
You can have as many loops as you want in any
program
9
Standard Pascal functions

• We need to be able to do basic math
• sqr - squares a number
• sqrt - takes square root of a number
• abs - absolute value of a number
• exp - ex
• ln - natural logarithm (base e)
• cos - cosine
• sin - sine
• for sin cos argument is considered to be in
  radians

10
Turbo Pascal built in functions

• upcase - gets upper case version of a
  character
• frac - gets fractional part of a real
• int - gets integer part of a real
• random - gets random number in the range
  0, 1
• random(N) - gets random number in the range 0,
  N-1

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Why do we need random???

• A lot of different applications
• Lets look at some (fun) examples

12
Homework

• Read the rest of the Chapter 5
• Program 3 Page 204 15 a,b
• due Monday, October 19th

13
Programs from this lecture

• Ordinal types
• Alphabet
• 1 letter at a time
• GenX
• Standard Pascal functions
• TP functions
• Random stars
• Dice game