Functions

The complexity of the software we build expands as we build it. In part, this becomes unavoidable because the mass of the software itself also expands. However, we can definitely avoid the complexity of repeating blocks of code. Modern software development products give us a way to place one copy of a repeating block of code in one defined location. Then, in the software, we can replace all repeated instances of that code block with a call to that one defined copy of the code. We call this one defined block of software a function. Think of a function as a box that takes in zero or more values and returns one or more values in a structured way. A function simplifies software, and it makes the software we build much easier to maintain, repair, and enhance. If a program has the same identical code block repeated one hundred times, the same required change to all of those blocks would require the same work and testing—one hundred times. If we replace those blocks with...