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Section 7.3 Worked Example: For Loops - Counter

Subgoals for Evaluating a Loop.

  1. Identify loop parts
    1. Determine start condition
    2. Determine update condition
    3. Determine termination condition
    4. Determine body that is repeated
  2. Trace the loop
    1. For every iteration of loop, write down values

Subsection 7.3.1

You can watch this video or read through the content below it.
Problem: Given the following code, what is the output?
total = 0;
for (int x = 5; x < 50; x++)
{
  if (x % 5 == 0)
     total += x;
}
System.out.println(total);

Subsection 7.3.2 SG1: Diagram which statements go together.

Figure 7.3.1.

Subsection 7.3.3 SG2: Define and initialize variables

Start:
x = 5
total = 0
End:
x >= 50
Figure 7.3.2.

Subsection 7.3.4 SG3: Trace the loop

Figure 7.3.3.
Figure 7.3.4.
X increments by 1, but the value is only added to total when it is evenly divisible by 5.
Notice that this example gives the equivalent for loop for the while loop in 6.1.
Answer.
Output is 225

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