6.2. Assessment: Writing Loops

Subgoals for Writing a Loop

1. Determine purpose of loop

   1. Pick a loop structure (while, for, do_while)

2. Define and initialize variables

3. Determine termination condition

   1. Invert termination condition to continuation condition

4. Write the loop body

   1. Update Loop Control Variable to reach termination

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Q1: Given the following code segment:

int x = 1;
while ( /* condition */ ) {
   if (x % 2 == 0) {
      System.out.print(x + "  ");
   }
   x = x + 2;
}

Consider the following conditions to replace /* condition */ in the code segment:

1. x < 0

2. x <= 1

3. x < 10

For which of the conditions will nothing be printed?

• I only
• II only
• I and II only
• I and III only
• I, II and III

Q2: Given the following code segment which is intended to print the number of integers that evenly divide the integer inputVal. (You may assume that inputVal > 0.)

int count = 0;
int inputVal = /* user entered value */
for (int k = 1; k <= inputVal; k++) {
   if ( /* condition */ ) {
      count++;
   }
} // end for
System.out.println(count);

Which of the following can be used to replace /* condition */ so that numDivisors will work as intended?

• inputVal % k == 0
• k % inputVal == 0
• inputVal % k != 0
• inputVal / k == 0
• k / inputVal > 0

Q3: Which of the following code segments will produce the output:

1 4 7 10 13 16 19

int k = 1;
while (k < 20) {
   if (k % 3 == 1)
      System.out.print(k + "  ");
   k = k + 3;
}

for (int k = 1; k < 20; k++) {
   if (k % 3 == 1)
      System.out.print(k + "  ");
}

for (int k = 1; k < 20; k = k + 3) {
   System.out.print(k + "  ");
}

• I only
• II only
• I and II only
• I and III only
• I, II and III

Q4: What is the maximum number of times “Hello” can be printed?

int k = // a random number such that 1 <= k <= n ;
for (int p = 2; p <= k; p++) {
   for (int r = 1; r < k; r++)
      System.out.println("Hello");
}

• 2
• n - 1
• n - 2
• (n - 1) * (n - 1)
• n * n

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