Question

What are the values of i and n after the following code is executed:
int i= 10;
int n=l++i)%5;​

Answer 1

Explanation:

Consider the following code snippet:

arrayOfInts[j] > arrayOfInts[j+1]

Question: What operators does the code contain?

Answer: >, +

Consider the following code snippet:

int i = 10; int n = i++%5;

Question: What are the values of i and n after the code is executed?

Answer: i is 11, and n is 0.

Question: What are the final values of i and n if instead of using the postfix increment operator (i++), you use the prefix version (++i))?

Answer: i is 11, and n is 1.

Question: To invert the value of a boolean, which operator would you use?

Answer: The logical complement operator "!".

Question: Which operator is used to compare two values, = or == ?

Answer: The == operator is used for comparison, and = is used for assignment.

Question: Explain the following code sample: result = someCondition ? value1 : value2;

Answer: This code should be read as: "If someCondition is true, assign the value of value1 to result. Otherwise, assign the value of value2 to result."

Exercises

Change the following program to use compound assignments:

class ArithmeticDemo { public static void main (String[] args){ int result = 1 + 2; // result is now 3 System.out.println(result); result = result - 1; // result is now 2 System.out.println(result); result = result * 2; // result is now 4 System.out.println(result); result = result / 2; // result is now 2 System.out.println(result); result = result + 8; // result is now 10 result = result % 7; // result is now 3 System.out.println(result); } }

Here is one solution:

class ArithmeticDemo { public static void main (String[] args){ int result = 3; System.out.println(result); result -= 1; // result is now 2 System.out.println(result); result *= 2; // result is now 4 System.out.println(result); result /= 2; // result is now 2 System.out.println(result); result += 8; // result is now 10 result %= 7; // result is now 3 System.out.println(result); } }

In the following program, explain why the value "6" is printed twice in a row:

class PrePostDemo { public static void main(String[] args){ int i = 3; i++; System.out.println(i); // "4" ++i; System.out.println(i); // "5" System.out.println(++i); // "6" System.out.println(i++); // "6" System.out.println(i); // "7" } }

The code System.out.println(++i); evaluates to 6, because the prefix version of ++ evaluates to the incremented value. The next line, System.out.println(i++); evaluates to the current value (6), then increments by one. So "7" doesn't get printed until the next line.