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Delete Array Manipulation Notes.md
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# Arrays
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## What is an Array?
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- Object used to store a **list** of values
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- All values in array are the **same type**
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-Eg. int, double, char, string, etc
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- Used to store a large number of data
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- Easy to **access** any element in the array
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## How to Declare
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- Declaring an array to up to 10 words
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```java
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String array[] = new String[10];
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```
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- Declaring an array and initializing variables at the same time:
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```java
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String array[] = {"s", "d", "f"};
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```
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## String Manipulataion
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- `length()` to find the length of a string
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- `stringName.charAt(0)` will output the first character
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- Each character in a string has a positio. String positions start at 0
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- `stringName.indexOf("T")` will output the index number that the letter `T` belongs to
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- `stringName.substring(3)` will output all characters after the index #
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- Eg. `string stringName = "Jim hates math"`
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- Output: `hates math`
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- First # is for the index that you want and last number is for the index that you don't want
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- `stringName2 = " i hate math "`
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- `stringName2.trim();`
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- Output: `i hate math`
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- `stringName.toLowerCase()` makes every character a lower case letter
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- `stringName.toUpperCase()` makes every character an upper case letter
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- `concat()`
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- `stringname1.concat(stringname2);` will put both string into 1 word
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- `stringname.replace("a", "p");` will replace every `a` with `p`
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- `stringname1.equals(stringname2);` will return true of false depending on whether the two contain the same value
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- `stringname1.compareTo(stringname2);` is for alphabetical order
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- if the condition above is $`< 0`$, name1 is before name2. $`> 0`$, name1 is after name2, if $`=0`$, its the same string
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## Sorting
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```java
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static void ImprovedBubbleSorted(int arr[]) {
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boolean isSorted = false;
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int j = 1;
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while(!isSorted) {
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isSorted = true;
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for(int i = 0; i < arr.length - j; i++) {
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if(arr[i]> arr[i + 1]) {
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int t = arr[i];
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arr[i] = arr[i + 1];
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arr[i + 1] = t;
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isSorted = true;
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}
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}
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j++;
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}
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}
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```
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## Searching
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```java
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boolean found=false;
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System.out.println("Enter the word you want to search");
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String word = sc.next();
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for(int i=0; i<arr.length; i++) {
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if(arr[i].equals(word)) {
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found=true;
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}
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}
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if(found) {
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System.out.println("The word was found");
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}
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else {
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System.out.println("The word was not found");
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}
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```
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## Searching Continued
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```java
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boolean found=false;
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System.out.println("Enter the word you want to search");
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String word = sc.next();
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int pos=0;
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for(int i=0; i<arr.length; i++) {
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if(arr[i].equals(word)) {
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found=true;
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pos=i;
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}
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}
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if(found) {
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System.out.println("The word was found at index: " + pos);
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}
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else {
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System.out.println("The word was not found");
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}
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```
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## Conclusion
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- Arrays are very useful when problem solving when a large numbe of data is involved
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- `Organize` large sets of data
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- Variety of ways you can access information in an array
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