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content/ta/spring2018/cpsc220/mar13.md

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+# Lecture for March 13th
+
+## Methods
+
+Methods are small blocks of statements that make it easier to solve a problem. It usually focuses on solving a small part of the overall problem.
+
+Usually in methods you provide some sort of input and get some output out of it.
+
+### Advantages
+
+- Code readability
+- Modular program development (break up the problem in chunks)
+- Incremental development
+- No redundant code!
+
+### Method definition
+
+Consists of a method name, input and output and the block of statements.
+
+Usually this is succinctly written using JavaDocs which is what you see in the JavaAPI
+
+### Method Call
+
+A method call is the execution of the method. The statements defined in the method is what will execute.
+
+### Method Stubs
+
+Recall from method definition the parts of the method definition. Now look at the following method
+
+```java
+String[] split(String s)
+```
+
+The output here is `String[]`
+
+The method name is `split`
+
+The input is `String s`
+
+## Modular Programming
+
+Let us look at the following example:
+
+The program should have a list of grocery prices. It should be able to calculate the total cost of groceries. The store gives a student discount of 5%. The program should calculate this discount and update the total, it should calculate and add the 2.5% tax.
+
+- First you should add it all up
+- Then compute the discount
+- Then add the tax
+
+## Parts of a method definition
+
+```java
+public static int timesTwo(int num) {
+    int two = num * 2;
+    return two;
+}
+```
+
+It first starts off by declaring the visibility `public`
+
+The return type if `int`
+
+The method name is `timesTwo`
+
+The input parameter is `int num`
+
+Between the curly braces is the *body* of the method
+
+## Calling a Method
+
+```java
+int a = 5;
+int b = 3;
+
+int ans = multiply(a, b)
+```
+
+The method call is `multiply(a, b)` and the result is stored in the variable `ans`