1.6 Conditional processing

When you write code, you create instructions for a computer that state what steps the computer must take to accomplish some task. In that sense, you are specifying a recipe. Depending on some conditions, like if a bank balance is positive or a car’s speed exceeds a stated limit, the sequence of steps may vary. We call how your code moves from one step to another its flow.

Let’s make some bread to show where a basic recipe has points where we should make choices.

Figure 1.1: Loaves of bread. Photo by the author.

Ingredients

• 1 ½ tablespoons sugar
• ¾ cup warm water (slightly warmer than body temperature)
• 2 ¼ teaspoons active dry yeast (1 package)
• 1 teaspoon salt
• ½ cup milk
• 1 tablespoon unsalted butter
• 2 cups all-purpose flour

Straight-through...