mirror of
https://github.com/Brandon-Rozek/website.git
synced 2024-11-22 16:26:28 -05:00
74 lines
No EOL
1.3 KiB
Markdown
74 lines
No EOL
1.3 KiB
Markdown
# Lecture for February 13
|
|
|
|
## Loops
|
|
|
|
###Why Loops?
|
|
|
|
While some check is true, repeat the work.
|
|
|
|
While the cookies aren't baked, keep baking
|
|
|
|
### Loop Building Process
|
|
|
|
1. Identify one test that must be true when the loop is finished
|
|
2. Use the **opposite** form of the test
|
|
3. Within loop, make *progress* towards completion of the goal.
|
|
|
|
### While syntax
|
|
|
|
```java
|
|
while (expression) {
|
|
// Loop body executes if expression is true
|
|
}
|
|
// Statements execute after expression is false
|
|
```
|
|
|
|
### Getting Input (Songs in a Playlist Psuedocode)
|
|
|
|
```java
|
|
// Ask user about first song
|
|
while (user says play next song) {
|
|
// play next song
|
|
// ask user about next song
|
|
}
|
|
```
|
|
|
|
### Nested Loops
|
|
|
|
You can have loops inside loops
|
|
|
|
```java
|
|
int outer = 1;
|
|
while (outer < 4) {
|
|
int inner = 1;
|
|
while (inner < 4) {
|
|
System.out.println(outer + ":" + inner);
|
|
inner++;
|
|
}
|
|
outer++;
|
|
}
|
|
```
|
|
|
|
This code does the following
|
|
|
|
```reStructuredText
|
|
1:1
|
|
1:2
|
|
1:3
|
|
2:1
|
|
2:2
|
|
2:3
|
|
3:1
|
|
3:2
|
|
3:3
|
|
```
|
|
|
|
### Break Down the Problem
|
|
|
|
Never write the entire program at once! This makes it incredibly hard to debug. Instead break it into small parts.
|
|
|
|
Write one part -> debug until it works
|
|
|
|
Write second part -> debug until it works
|
|
|
|
This way you know which part of your code failed, instead of having everything fail. |