“A friend of mine returned from an expedition yesterday.” The students attentively listened, for stories from beyond Rorohiko were rare. “They flew over a forest in a gyroplane.” He looked around. “Does anyone know what a gyroplane is?” He pointed to a student with his hand raised.

“A vehicle capable of flying in any direction or hovering in place using its propellers.”

“Yes, what is your name?”

“Roy.”

“Roy, do you know how we can keep its propellers turning?”

He thought for a moment, then shrugged. “I’m not sure what you mean.”

“How can we run code repeatedly?”

He thought some more. “Wouldn’t you have to keep executing the code again and again?”

“Yes, do you know how to write that in code?”

“No, unless you’re about to teach us how to do it at runtime.”

Vick smiled, he knew this class was different. “Yes. Today, you will learn how.”

while (true) { Console.WriteLine(“Looped!”); }

“Above me,” he pointed to the screen, “is a ‘while loop.’” He executed the code. ‘Looped!’ it said. Then, on the line under it: ‘Looped!’ Then, on the line under that: ‘Looped!’ Then, over and over and over. “It will continue to execute as long as its condition is true. What we’ve created is an infinite loop.”

int i = 0; while (i < 5) { i = i + 1; Console.WriteLine(“Loop #” + i); }

He ran the code, and after displaying five lines, ‘Loop #1,’ ‘Loop #2…’ the program completed its execution. “The condition is checked before the execution of the loop. The loop is only executed if the condition is true. What we’ve made is essentially a ‘for loop.’”

for (int i = 0; i < 5; i = i + 1) { Console.WriteLine(“Loop #” + (i + 1)); }

He ran the code again, and it displayed the same five lines. “Instead of declaring an integer beforehand, and incrementing it in the loop, we can declare it, condition it, and increment it in a single line. That’s the power of a for loop. Note how we add one to the variable ‘i’ before concatenating it. This is because, in a for loop, the increment occurs after the loop’s execution. Whereas, before we incremented ‘i’ at the start of the loop.”

do { Console.WriteLine(“Looped!”); } while (true);

“The last loop is similar to a while loop,” he raised a finger, “with one important distinction. It executes at least once. Meaning, it executes once, then evaluates the condition to figure out if it should execute again. This is a ‘do while loop.’ Or simply, ‘do loop.’” He looked over the class, looking each student in the eye. “If you are to become apprentices, you must be wary with your use of loops.” His voice was uncomfortably firm, almost grim. “We will entrust you with precious resources, if you accidentally make an infinite loop where resources are expunged, there will be grave consequences.” He diverted his attention back to the computer. “Now, what does this have to do with gyroplanes? Well, their propellers need constant energy to spin.”

bool isOn = true; while (isOn) { Console.WriteLine(“Spin!”); }

‘Spin!’ said the screen over and over. “Yes, it is an infinite loop. However, another process would be occurring between each loop. That process would detect if a button was pressed which toggles the boolean. When that button is pressed, the loop will evaluate its condition as false, stopping it.”

for (float speed = 1f; speed < 20f; speed += 2f) { Console.WriteLine(“Spinning at speed: ” + speed); }

“The ‘f’ letter at the end of the numbers is to indicate it as a float in this language, not to be confused for an integer. The speed of the propeller can be controlled with each execution of the loop. Begins at one, only executes if it’s below twenty, increments by two every loop.” He walked closer to the class and stood taller. “Because of our great wizards, we were able to construct hardware that made it impossible for a propeller to spin too fast. So, even if we made an error where the speed became an enormous number, the propeller would simply rotate at its max speed dictated by its hardware. Just as integers and floats have a min and max range, so does the speed of a propeller. Zero being its min, and around four-hundred being its max.”

“What does ‘speed += 2f’ mean?” asked Willard.

“That’s shorthand for incrementing by two, and then setting that value to the variable.”

After class, the three huddled to converse. “Hey,” said Willard. “Does anyone know what a forest is? I heard Mister Vick use that word.”

“I’m not sure,” said Andrew, and Gus shrugged.

“It’s a massive cluster of trees,” said Roy, from down the hall, and walked towards them.

“Like, five or so?” asked Willard.

“No,” said Roy and stretched his arms to his sides. “A thousand kilometers, maybe more.”

Everyones’ jaw dropped. “What?” said Gus.

“A thousand kilometers? That’s impressive,” said Andrew.