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Semester 1/Programming 1/Week 5/Week 5 Programming 1 - Arithmetic, Typecasting & Boolean.md

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+## Lecture 1 - Identifiers, Arithmetic and Boolean
+
+- Internal format of the type is predefined for numerical data types. You cannot assign a higher precision variable to a lower precision variable.
+
+```java
+float pi = 3.14159; //invalid
+float pi = 3.14159f; //valid
+```
+
+- float -> double
+- double -/> float
+
+## Lecture 2 (14:00)
+
+### Arithmetic
+
+- 4i/3i = 1 - Any remainder is discarded as they are both integers
+- 4.0d/3.0d = 1.333333333… - This is an example of an overloaded operator
+- When types are mixed, a process called **arithmetic promotion** takes place. Operand of the lower precision is converted to the higher precision type so that the evaluation can proceed on operands of the same type.
+	- This is carried out automatically and is an example of implicit type conversion.
+
+#### Arithmetic Promotion
+
+- If either operand is a double - other operand is converted to double
+- else, if either operand is float, other operand is float
+- else, if either operand is long, other operand is long
+- else, converted to int
+
+### Type Casting
+
+- Explicitly converting one type to another
+
+```java
+double length = 151.4;
+double height = 255.7;
+int area = length * height; //invalid
+```
+
+- Values of length and height are large and we are not concerned about loss of precision. We can rewrite the last line as:
+
+```java
+double length = 151.4;
+double height = 255.7;
+area = (int) (length * height); //valid
+```
+
+- When converting a double or float, the value after the floating point are discarded, **truncated**. ex. (int) 2.99 = 2i.
+
+### Boolean
+
+```java
+int i = 5;
+boolean iPositive = i>0; //TRUE
+```
+
+- && - produces TRUE if both sides are true
+- || - produces TRUE is one side is true.
+
+### Object and Memory Diagrams
+
+- null = nothing
+```java
+Account account;
+```
+- This causes a memory location to be reserved for account.
+```java
+account = new Account(100);
+```
+- This causes account to be instantiated with a balance of 100
+```java
+Account account;
+account = new Account(250);
+account = new Account(700);
+```
+- After declaration and execution of the first assignment, the state of the memory diagram is:
+	- Account => Account (Balance = 250) => Account ~~(Balance 250)~~ (Balance 700).
+	- This is an example of Garbage Collection.
+	- Read up to w5 slide 39.
+
+Next homework next Wednesday. Based mainly on Homework 1.

Semester 1/Programming 1/Week 5/Workshop 5/README.TXT

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+------------------------------------------------------------------------
+This is the project README file. Here, you should describe your project.
+Tell the reader (someone who does not know anything about this project)
+all he/she needs to know. The comments should usually include at least:
+------------------------------------------------------------------------
+
+PROJECT TITLE:
+PURPOSE OF PROJECT:
+VERSION or DATE:
+HOW TO START THIS PROJECT:
+AUTHORS:
+USER INSTRUCTIONS:

Semester 1/Programming 1/Week 5/Workshop 5/package.bluej

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+#BlueJ package file
+objectbench.height=76
+objectbench.width=686
+package.editor.height=400
+package.editor.width=560
+package.editor.x=20
+package.editor.y=51
+package.numDependencies=0
+package.numTargets=1
+package.showExtends=true
+package.showUses=true
+project.charset=UTF-8
+target1.editor.height=700
+target1.editor.width=900
+target1.editor.x=491
+target1.editor.y=190
+target1.height=50
+target1.name=test
+target1.naviview.expanded=true
+target1.showInterface=false
+target1.type=ClassTarget
+target1.typeParameters=
+target1.width=80
+target1.x=70
+target1.y=10

Semester 1/Programming 1/Week 5/Workshop 5/test.ctxt

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+#BlueJ class context
+comment0.params=
+comment0.target=int\ modify()
+comment1.params=
+comment1.target=test()
+comment1.text=\n\ Constructor\ for\ objects\ of\ class\ test\n
+comment2.params=
+comment2.target=float\ sampleMethod()
+comment2.text=\n\ An\ example\ of\ a\ method\ -\ replace\ this\ comment\ with\ your\ own\n\ \n\ @param\ \ y\ \ \ a\ sample\ parameter\ for\ a\ method\n\ @return\ \ \ \ \ the\ sum\ of\ x\ and\ y\ \n
+numComments=3

Semester 1/Programming 1/Week 5/Workshop 5/test.java

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+
+/**
+ * Write a description of class test here.
+ * 
+ * @author (your name) 
+ * @version (a version number or a date)
+ */
+public class test
+{
+    // instance variables - replace the example below with your own
+    private int sum1, sum2;
+    private float number;
+    private double total;
+
+    public void modify( int num )
+    {
+        num = 10;
+        System.out.println( num );
+    }
+    
+    modify();
+    
+    /**
+     * Constructor for objects of class test
+     */
+    public test()
+    {
+        // initialise instance variables
+        sum1 = 10; 
+        number = 2.5f; 
+        sum2 = 20;
+        total = 10.25d;
+    }
+
+    /**
+     * An example of a method - replace this comment with your own
+     * 
+     * @param  y   a sample parameter for a method
+     * @return     the sum of x and y 
+     */
+    public float sampleMethod()
+    {
+        // put your code here
+        number = sum1 / sum2;
+        return number;
+    }
+}