COMP 110 More Loops and Strings

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COMP 110More Loops and Strings

• Tabitha Peck M.S.
• February 18, 2008
• MWF 3-350 pm
• Philips 367

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Announcements

• Programs
• START EARLY!!!!
• Should take 10-15 hours
• Should NOT take 20 hours
• Get help if you are stumped
• Office hours are helpful
• Read Instructions

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Announcements

• Program 2
• Format to 2 decimal places
• Convert floating point numbers to integers for
  modular arithmetic
• String parsing
• Comments and pseudocode

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Program 2 Grades
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Formatting Decimals (Jan 30)

• import java.text.
• DecimalFormat df new DecimalFormat("0.00")
• df.format(myVariable)
• Example code on class website

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• import java.text.DecimalFormat
• public class DecFormat
• public static void main(String args)
• DecimalFormat df new
  DecimalFormat("0.00")
• DecimalFormat df2 new
  DecimalFormat("0.0000")
• double d 12.345678
• System.out.println("my double with two
  decimal places " df.format(d))
• System.out.println("my double with four
  decimal places " df2.format(d))

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Converting to Integers

• You must convert floating-point numbers to
  integers to perform modular arithmetic.
• Modular arithmetic is defined for integers!!!
• Type Casting (Jan 23)
• myInt (int)myFoat
• answer (int)operand1 (int) operand2

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String parsing

• Lab 2
• Requests for more practice
• Today More Practice

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Comments

• double answer op1 op2
• answer 100answer
• int ans (int)answer
• answer (double)ans
• answer answer/100
  JOptionPane.showMessageDialog(null, inputString
  " " answer)

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Comments

• /For every calculation here on out, once the
  original operation is done, the answer is
  multiplied by 100, changed to an integer, then
  divided by 100 in order to give it the two
  decimal places required by the assignment. This
  comment will not be repeated for these operations
  again./

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Pseudocode

• Figure out how to solve the problem BEFORE you
  start coding
• Who had a hard time parsing the input string?
• What if you spent an hour before coding thinking
  about how to solve it?

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• I originally had a little trouble trying to
  figure out how to start (program2) as well. But
  on the way home Friday, it hit me that the user
  was inputting a string and that string had to be
  converted to the parts needed. Since the user
  was required to input a string with spaces, I
  figured using the spaces to convert the needed
  information would be the easiest way.

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Pseudocode

• Input a string (num operator num)
• Hmm? There is a space between everything.
• Find index of first space
• Get substring from beginning to first space
• Convert to double

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Pseudocode

• Once you think about how to solve the problem
• Then you start coding

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Announcements (continued)

• Project 3
• Assigned today
• Due March 4
• If you have problems come see me (soon)
• Coming to class late

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You should

• NOT spend gt 10 hours per week on this class (on
  average)
• start assignments early
• get help if you are stumped (before you get
  frustrated)
• Read the assignment carefully

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Questions?

• Suggestions / concerns / comments
• Please send them to me

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Today in COMP 110

• Practice String Parsing
• Practice loops - code on web
• Worksheet
• hand in for class participation
• Answers posted on website tonight

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Wednesday

• Classes
• you will need this for program 3

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