POPCORN HACK: Run the code.. what happened? How can we fix it?

Tell us below!

There were two problems that could essentialy fix the code, first it never exits the loop. And second you need to subtract sub.length from word.length

Another issue:

I T E R A T E

What if our substring was the word “RATE”? Note that RATE is at the end of the whole string

HACKS

Create a algorithm similar to the one above. Except this time, use iteration to count the number of vowels within the main string.

HINT: Use the boolean expressions we have learned in previous lessons. Which would you use when comparing your “window” with multiple options of substrings?

Popcorn HACK

When the targetNumber is found, you can print a message and use the break statement to exit the loop. When it’s not found, you can print a message indicating that the number was not found.

public class BreakHack {
    public static void main(String[] args) {
        int targetNumber = 42; //numb we want
        int[] numbers = {10, 20, 30, 40, 50, 60, 70}; //numb array
        boolean found = false; // A boolean to keep track of whether the target number is found

        for (int number : numbers) {
            if (number == targetNumber) {
                found = true;
                // Print a message if the number is found
                System.out.println("Number " + targetNumber + " is found!");
                // Break out of the loop
                break;
            }
        }

        // Check if the number isn't found and print a message if it's not found
        if (!found) {
            System.out.println("Number " + targetNumber + " wasn't found.");
        }
    }
}
BreakHack.main(null);

import java.util.Scanner;

public class InteractivePyramid {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.print("Enter the symbol you want to use: ");
        char symbol = scanner.next().charAt(0);

        System.out.print("Enter the number of rows for the pyramid: ");
        int numRows = scanner.nextInt();

        for (int i = 1; i <= numRows; i++) {
            //print space before the symbol
            for (int j = 1; j <= numRows - i; j++) {
                System.out.print(" ");
            }

            //print
            for (int k = 1; k <= 2 * i - 1; k++) {
                System.out.print(symbol);
            }

            System.out.println(); //next line
        }
        scanner.close();
    }
}
InteractivePyramid.main(null)

Hacks

Modify pyramid code:

Create different patterns (other then pyramid) by modifying nested loop structure

Questions

What is a nested iteration, continue statement, and break statement (in your own words)?
Create a simple example of a continue statement or break statement

4.5 Informal Code Analysis

Learning objective: Compute statement execution counts & informal run-time comparison of iterative statements

Essential Knowledge: A statement execution count indicates the number of times a statement is executed by the program

What IS informal code analysis?

Answer:

// CODE EXAMPLE #1 (for loop)
public class InformalCodeAnalysis {
    public static void main(String[] args) {
        int count = 0;
        for (int k = 0; k < 30; k++)
        {
            if (k % 3 == 0) // statement 1
            {
                count++; // statement 2
            }
        }
    }
}

How many times will statement 1 execute?

Answer: How many times will statement 2 execute?

Answer:

// CODE EXAMPLE #2 (for loop)
public class InformalCodeAnalysis {
    public static void main(String[] args) {
        int count = 0;
        for (int k = 4; k < 30; k+=3)
        {
            count++; // statement 3
        }
    }
}

How many times will statement 3 execute?

Answer:

// Rewrite the code segment below to have a faster run-time based on statement execution counts
for (int k = 0; k < 135; k++)
{
    if (k % 5 == 0)
    {
        System.out.println(k);
    }
}

// CODE EXAMPLE #3 (while loop)

int num = (int)(Math.random() * 10);
while (num % 2 != 0)
{
    num = (int)(Math.random() * 10); // statement 4
}

What is the min/max number of times statement 4 will execute?

Answer:

// CODE EXAMPLE #4 (nested loop)

for (int outer = 0; outer < 3; outer++)
{
    for (int inner = 0; inner < 4; inner++)
    {
        // statement #5
    }
}

How many times will statement #5 execute?

Answer:

// CODE EXAMPLE #5 (nested loop)

int k = 0;
while (k < 5)
{
    int x = (int)(Math.random() * 6) + 1;
    while (x != 6)
    {
        // statement #6
        x = (int)(Math.random() * 6) + 1;
    }
    k++;
}

How many times will statement #6 execute?

Answer: We don’t knowf

4.5 Hacks

#1 How many times will statement #1 and statement #2 execute in the code segments below?

for (int k = 0; k < 1000; k++)
{
    // statement #1
}

for (int k = 6; k < 50; k++)
{
    // statement #2
}

#2 How many times will statement #3 execute for the code segment below?

int k = 1;
while (k <=7)
{
    for (int z = 0; z < 4; z++)
    {
        // statement #3
    }
    k++;
}

#3 Create 3 seperate code segments that execute a statement 10 times using:

(a) a for loop

(b) a while loop

// 3a code

// 3b code

// 3c code