COMP 110 More Loops and Strings Tabitha Peck M.S. February 18, 2008 MWF 3-3:50 pm Philips 367 1

Announcements Programs START EARLY!!!! Should take hours Should NOT take 20+ hours Get help if you are stumped Office hours are helpful Read Instructions 2

Announcements Program 2 Format to 2 decimal places Convert floating point numbers to integers for modular arithmetic String parsing Comments and pseudocode 3

Program 2 Grades 101% - 110%9 90% - 100%13 80% - 89%5 70% - 79%2 0% - 69%2

Formatting Decimals (Jan 30) import java.text.*; DecimalFormat df = new DecimalFormat("0.00"); df.format(myVariable); Example code on class website 5

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 = ; System.out.println("my double with two decimal places: " + df.format(d)); System.out.println("my double with four decimal places: " + df2.format(d)); } 6

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; 7

String parsing Lab 2 Requests for more practice Today == More Practice

Comments double answer = op1 + op2; answer = 100*answer; int ans = (int)answer; answer = (double)ans; answer = answer/100; JOptionPane.showMessageDialog(null, inputString + " = " + answer);

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.*/

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?

“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.”

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

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

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

You should… NOT spend > 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

Questions? Suggestions / concerns / comments Please send them to me 17

Today in COMP 110 Practice String Parsing Practice loops - code on web Worksheet hand in for class participation Answers posted on website tonight 18

Wednesday Classes you will need this for program 3 19