Notebook

Unit 4 Iteration Notes¶

Unit 4 Iteration Notes

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title: Unit 4 Iteration Notes
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A Boolean expression is a Java expression that returns a Boolean value: true or false

Rather than implementing mathematical operators such as "+" or "-", comparative or boolean operators such as "==" or "!" can be used.

In Java two if statements could be used if both if statement conditions could be true at the same time.

Java supplies a primitive data type called Boolean, instances of which can take the value true or false only

In [1]:

import java.lang.Math;
import java.util.Scanner;

public class NumberGuess {
    private int answer;
    private int guess;
    Scanner in = new Scanner(System.in);
    public NumberGuess() {
        this.answer = (int) Math.floor(Math.random()*10 + 1);
        System.out.println(answer);
    }
    public void play() {
        while (answer != guess) {
            this.getGuess();
        }
        in.close();
    }
    public void getGuess() {
        System.out.print("Guess a number 1-10: ");
        this.guess = in.nextInt();
        System.out.println(this.guess);
        if (this.guess > this.answer) {
            System.out.println("too high");
        } else if (this.guess < this.answer) {
            System.out.println("too low");
        } else {
            System.out.println("congrats");
        }
    }
    public static void main(String[] args) {
        NumberGuess num = new NumberGuess();
        num.play();
    }
}

Second Homework Assignment¶

Second Assignment

For Loop: A loop that iterates through its index

In [3]:

for (int i = 0; i<100; i+=3) {
    System.out.println(i);
  }

Enhanced For Loop: Used to iterate through arrays.

In [7]:

int[] arr = {93, 24, 4, 3, 87,545,76,12,64,30};

for (int i : arr) {
    System.out.println(i);
  }

While Loop: Runs as long as a boolean condition is true and has the boolean condition checked before each iteration is ran Do While Loop: Similar to a While loop, however, the conditon is only checked after each iterative portion of the code is ran --> the code will execute at least one action.

In [14]:

int i = 0;

// printing even numbers with while loop
while (i < 1100) {
  System.out.println(i);
  i += 8;
}

Nested Loops: Loops placed within each other, creating better iteration, most optimal for 2D arrays

In [17]:

int[][] arr = {
    {6, 9, 33},
    {27, 43, 94},
    {4, 35, 2}
  };
  

  for (int i = 0; i<arr.length; i++) {

    for (int j = 0; j<arr[i].length; j++) {
        
      System.out.print(arr[i][j] + " ");
    }
    System.out.println();
  }

6 9 33 
27 43 94 
4 35 2