Question

Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it.

Brian Kernighan and P.J. Plauger, The Elements of Programming Style

A program is crystallized thought. Sometimes those thoughts are confused. Other times, mistakes are introduced when converting thought into code. Either way, the result is a flawed program.

Flaws in a program are usually called bugs. Bugs can be programmer errors or problems in other systems that the program interacts with. Some bugs are immediately apparent, while others are subtle and might remain hidden in a system for years.

Often, problems surface only when a program encounters a situation that the programmer didn’t originally consider. Sometimes such situations are unavoidable. When the user is asked to input their age and types orange, this puts our program in a difficult position. The situation has to be anticipated and handled somehow.

This is a book about getting computers to do what you want them to do. Computers are about as common as screwdrivers today, but they contain a lot more hidden complexity and thus are harder to operate and understand. To many, they remain alien, slightly threatening things.