9.1. What is Debugging?

Programming is a complex process. Since it is done by humans, mistakes often occur. Programming errors are called bugs, and the process of tracking bugs down and fixing them is called debugging.

One popular story claims that in 1947, a dead moth caused a problem in one of the first computers. The term bug has remained in use since, and it refers to anything that prevents a program from working correctly. Wikipedia even has an image of the supposed first bug.

Three kinds of errors can occur in a program: syntax errors, runtime errors, and logic errors. We will examine each type of error in this chapter, explore some useful debugging strategies, and then review good habits that help reduce errors.

9.1.1. Beginning Tips for Debugging

Debugging a program requires a different approach compared to writing the original code. As you debug, think of yourself as a detective. Something has gone wrong, and you must use clues, experience, intuition, trial and error, and a logical approach to solve the problem.

Here are some suggestions to get you thinking about debugging:

  1. Often, new coders find it tempting to blame errors on Python itself. However, it is far, far more likely that the human put the error into their own code.

  2. Think critically about the code. Use any available tools to help find and fix the mistakes. Even senior developers make basic errors!

  3. Learn how to use error messages and print statements to find clues.

Over time, you will sharpen your debugging skills and learn how to prevent bugs from occurring in the first place.

9.1.2. Check Your Understanding


Debugging is:

  1. finding all the errors in the program.
  2. fixing all the errors in the program.
  3. finding and fixing all the errors in the program.