Creative Development

Most computing innovations are built by teams, and people with different backgrounds, skills and points of view spot needs and problems that one person would miss. Teams share work through practices like pair programming and online tools, and they ask users for feedback through surveys, interviews and testing.

Every program is written for a purpose, like solving a problem or letting people express themselves, and knowing that purpose helps you design and test it. A program takes input (from a user, a sensor or another program), runs its code and produces output, and many programs are event-driven: code runs when something happens, like a click or a key press.

Building a program means investigating what users need, then designing, prototyping and testing. Development can be iterative (you go back and refine based on feedback) or incremental (you build and test small pieces, then add them together), and comments and other documentation explain your code and credit any code you used that someone else wrote.

There are four kinds of error to know. A logic error means the program runs but does the wrong thing; a syntax error means the code breaks the language's rules; a run-time error happens while the program is running, like using a list index that doesn't exist; and an overflow error happens when a number is outside the range the available bits can hold. You find errors by testing with inputs you pick (including values at the edges of what's allowed) and comparing the output with what you expected, and by tracing the code by hand, using a debugger or adding extra output statements.