All Flashcards
What is the key principle behind using a while loop?
To repeatedly execute a block of code as long as a specified condition remains true.
Why is it important to avoid infinite loops?
Infinite loops can crash your program by consuming resources indefinitely.
What is the purpose of a loop control variable?
To control the number of iterations in a loop and ensure it terminates correctly.
Explain the concept of a sentinel-controlled loop.
A loop that continues until a specific input (the sentinel) is entered, signaling the end of the loop.
Explain the concept of a flag-controlled loop.
A loop that continues until a specific condition is met within the loop, indicated by a flag variable.
What are the four loopy questions used for debugging loops?
- Does my loop start right? 2. Does my loop end right? 3. Does my loop make progress towards completion? 4. Will the method break in the middle of the loop?
How does exception handling make code more robust?
By preventing crashes due to runtime errors and allowing the program to gracefully handle unexpected situations.
What is the purpose of the throws keyword in a method signature?
It indicates that the method might throw a specific exception, which must be handled by the calling method.
What is the importance of initializing variables before using them in a loop?
Ensures that the loop starts with a known state and avoids unexpected behavior.
Explain the difference between a skipped loop and an infinite loop.
A skipped loop never executes because the condition is initially false, while an infinite loop never terminates because the condition is always true.
What are the steps to determine if a number is divisible by another number without using the modulo operator?
- Check for invalid input (negative number or non-positive divisor). 2. If the number is 0, return true. 3. While the number is greater than 0, subtract the divisor from the number. 4. Return true if the number is 0 after the loop, false otherwise.
What are the steps to extract digits from an integer?
- Check for invalid input (negative number). 2. While the number is not 0, print the last digit (number % 10). 3. Remove the last digit (number /= 10).
What are the steps to find the minimum value from a series of user inputs using a while loop?
- Initialize min with the first input number. 2. While the input is not the sentinel value, compare the input with min. 3. If the input is less than min, update min. 4. Get the next input.
What are the steps to find the maximum value from a series of user inputs using a while loop?
- Initialize max with the first input number. 2. While the input is not the sentinel value, compare the input with max. 3. If the input is greater than max, update max. 4. Get the next input.
What are the steps to compute the sum of a series of user inputs using a while loop?
- Initialize sum to 0. 2. While the input is not the sentinel value, add the input to sum. 3. Get the next input.
What are the steps to compute the average of a series of user inputs using a while loop?
- Initialize sum to 0 and counter to 0. 2. While the input is not the sentinel value, add the input to sum and increment counter. 3. Get the next input. 4. Calculate the average (sum / counter).
What does the following code output?
java
int i = 0;
while (i < 5) {
System.out.println(i);
i++;
}
0 1 2 3 4
Identify the error in the following code:
java
int i = 0;
while (i < 5) {
System.out.println(i);
}
The loop will run infinitely because the value of i is never updated.
What does the following code output?
java
int i = 5;
while (i > 0) {
System.out.println(i);
i--;
}
5 4 3 2 1
Identify the error in the following code:
java
int i = 10;
while (i > 0);
{
System.out.println(i);
i--;
}
The semicolon after the while condition creates an empty loop, and the subsequent block is executed only once.
What does the following code output?
java
int i = 0;
while (i < 10) {
if (i % 2 == 0) {
System.out.println(i + " is even");
}
i++;
}
0 is even 2 is even 4 is even 6 is even 8 is even
Identify the error in the following code:
java
int i = 0;
while (i < 5) {
System.out.println(i);
i++;
if (i == 3) {
break;
}
}
No error. This code will print 0, 1, and 2, then exit the loop.
What does the following code output?
java
int i = 0;
while (i < 5) {
i++;
if (i == 3) {
continue;
}
System.out.println(i);
}
1 2 4 5
Identify the error in the following code:
java
int number = -5;
while (number > 0) {
System.out.println(number);
number--;
}
The loop condition is initially false, so the loop body will never execute.
What does the following code output?
java
int i = 0;
while (true) {
System.out.println(i);
i++;
if (i > 5) {
break;
}
}
0 1 2 3 4 5
Identify the error in the following code:
java
int i = 0;
while (i < 5) {
System.out.println(i++);
}
No error. This code will print 0, 1, 2, 3, and 4.
What does the following code output?
java
int x = 10;
try {
int result = x / 0;
System.out.println("Result: " + result);
} catch (ArithmeticException e) {
System.out.println("Error: Division by zero");
}
Error: Division by zero