CPS 1 - Spring, 1999 - Ramm 2/1/99 #8

Announce
- Begin Reading Chapter 3

Strings and String Manipulation

Example Doing Some String Manipulation
StringPlay.java, StringPlay.html
An Algorithm: The Exchange Problem
- need temp
String x, y, temp; ... x = ____.getText(); y = ____.getText(); _____.setText(x + " and " + y " before"); ... temp = x; x = y; y = temp; ... _____.setText(x + " and " + y " after");
...
Example: Pig Latin
PigLatin.java, PigLatin.html
Add More Functions
- Does last name contain first?
Reading in Numbers
- Need something similar to TextField

New Classes for Numbers

public class IntField extends TextField
{
    public IntField();
    public IntField(int size);
    public void setInt(int number);
    public int getInt();
}
public class DoubleField extends TextField
{
    public DoubleField();
    public DoubleField(int size);
    public void setDouble(double num);
    public Double getDouble();
}

Using DoubleField in Example
Numbers.java, Numbers.html
More About Syntax
- more formal method
1. <identifier> -> //a sequence of letters and/or digits that begin with a letter//
  where // indicates italics in textbook
  read: an object called an 'identifier' can be ...
1. <compound statement> -> {
  //a sequence of <statements>s
  each followed by a semicolon//
  }
To Use: substitute, multiple times as necessary:

Statement Example
Want:


pigLatin = tail + firstL + "ay";

EXAMPLE:
<statement> -> <identifier> = <expression>;
  -> pigLatin = <expression>;
  -> pigLatin = <str expression>;
  -> pigLatin = <str expression> + <str expression>;
  -> pigLatin = tail + <str expression>;
  -> pigLatin = tail + <str expression> + <str expression>;
  -> pigLatin = tail + firstL + <str expression>;
  -> pigLatin = tail + firstL + "ay";

<compound statement>	->	{
		//a sequence of <statements>s
		each followed by a semicolon//
		}