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content/ta/spring2018/cpsc220/jan30.md

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+# Lecture for January 30
+
+## Random Number Generator
+
+One of the ways you can do a random number generator is through this method:
+
+Import a class called random 
+
+```java
+import java.util.Random;
+```
+
+Then you need to create a `Random` object
+
+```java
+Random rand = new Random();
+```
+
+After this you can call the  `nextInt()` method to get a random number between 0 and $2^{32}$
+
+```java
+int randInt = rand.nextInt();
+```
+
+If you don't want a random number between 0 and $2^{32}$ but instead to another maximum value, then you can call  the `nextInt` method inserting the max integer as a parameter.
+
+Random Integer from 0-10 (not including 10)
+
+```java
+int randInt2 = rand.nextInt(10);
+```
+
+## Output
+
+We have already encountered `System.out.println` and `System.out.print` but let us go over the differences again.
+
+`System.out.println()` prints the contents inside the parenthesis and appends a newline character afterwards so that the next output is on a new line
+
+`System.out.print()` prints the contents inside the parenthesis and does not output a newline character
+
+
+
+### Formatting Output
+
+If you want more control on how your output is displayed, it is recommended that you use `System.out.printf` to format your output
+
+First, you need to specify your type using the % instruction
+
+- d for integer
+- f for decimal
+
+Example:
+
+```java
+int sum = 50;
+System.out.printf("Total = %d", sum);
+```
+
+This outputs 
+
+```reS
+Total = 50
+```
+
+Notice here that there is no concatenation required like the previous two methods, instead you insert the variables as parameters
+
+Let us deconstruct the % instruction
+
+% __ __ . __ __
+
+The first underline is the + - 0 space (sometimes we want to pad the money with zeros)
+
+The second underline is the width of the text
+
+The third underline is the number of decimal places
+
+The the final underline is the specifier `f` for decimal and `d` for integer
+
+<u>Example</u>
+
+```java
+double amount = 0.5;
+System.out.printf("Total Due: %0.2f")
+```
+
+This outputs
+
+```reStructuredText
+Total Due: 0.50
+```
+