Unit 6.3 Lesson

• Enhanced For Loop (For-each)
  • Pros
  • Cons
• Regular For Loop
• Enhanced For Loop
• Comparing a regular for loop with the enhanced for loop
• Hacks

Final Hack

Enhanced For Loop (For-each)

An enhanced For Loop is a simplified version of a regular for loop, where the coder doesn’t need to specify the increment and can access each element directly.

Pros

• Can access the elements of a array instad of a counter
• Enhanced readability
• Less likely to be buggy

Cons

• Can only traverse the array in order
• Accesses a copy of the array, so modifications to the variables are not saved in the original array

Regular For Loop

Enhanced For Loop

int[] numbers = {10, 20, 30, 40, 50};
for (int number : numbers) {
    number += 1;
    System.out.println(number);
};

System.out.println(Arrays.toString(numbers))

Comparing a regular for loop with the enhanced for loop

Popcorn Hack: Rewrite this code to use an enhanced for loop instead. make comments explaining what you added/changed

String[] languages = {"Java", "Python", "Markdown", "C++", "Go", "JavaScript", "HTML"};

for (int i = 0; i<languages.length; i++) {
    System.out.println(languages[i]);
};

for (String lang : languages) { // here, I changed the iteration method in the parenthesis
    System.out.println(lang);
}

Hacks

1. Build the loop
2. Multiple Choice
3. Find each index of the letter ‘a’ in each word
4. Find the error
5. HW Hack

String[] yum = {"bozo", "monke", "skibidi", "ohio"};

for (String asdfghjkl : yum) {
    System.out.println(asdfghjkl);
}

private String[] myArray = {
    "And", "Table", "Shirts", "Tea", "School Day"
};

for (String currentWord : myArray) {
    System.out.println(currentWord.length());
}

// A: System.out.println(myArray.currentWord.length());
// B: System.out.println(myArray[index].length());
// C: System.out.println(myArray[currentWord].length());
// D: System.out.println(currentWord.length()); ✅

String[] fruits = {"Apple", "Banana", "Orange"};

for (String fruit: fruits) {
    int index = fruit.indexOf('a');
    System.out.println("The index of 'a' in " + fruit + " is: " + index);
};

String[] myArray = {"Object 1", "Object 2", "Object 3", "Object 4", "Object 5"};

for (String currentWord: myArray) { // Second error: The type of currentWord wasn't declared
    System.out.println(currentWord); // First error: There was originally no ".println"
    // Third error: There wasn't a semicolon after the previous line
};

// There are 3 errors, can you find them?

Final Hack

Add to the code below to create a average grade calculator (using an enhanced for loop)

Integer[] grades = {88, 93, 55, 68, 77};

Scanner userGrades = new Scanner(System.in);
System.out.print("Enter a grade: ");
int grade = Integer.parseInt(userGrades.nextLine());

double sum = 0;
for (int g : grades) {
    sum += g;
}
double average = sum / grades.length;
System.out.println("Average grade before student grade was added " + average);

grades = Arrays.copyOf(grades, grades.length + 1);
grades[grades.length - 1] = grade;
System.out.println(Arrays.toString(grades));

double sum2 = 0;
for (int g : grades) {
    sum2 += g;
}
double average2 = sum2 / grades.length;
System.out.println("Average grade after student grade was added " + average2);