August 1997
Beginner
454 pages
9h 32m
English
Content preview from Practical C Programming, 3rd EditionBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Chapter 15. Debugging and Optimization
Bloody instructions which, being learned, return to plague the inventor.
—Shakespeare, on debugging [Macbeth, Act 1, Scene
7].
Debugging
The hardest part of creating a program is not its design and writing, but its debugging phase. In this phase, you find out how your program really works (instead of how you think it works).
In order to eradicate a bug, you need two things: a way of reproducing it and information from the program that lets you locate and correct the problem.
In some cases, finding the bug is easy. You discover the bug yourself, the test department produces a clear and easy test plan that displays the bug, or else the output always comes out bad.
In some cases, especially with interactive programs, reproducing the bug may be 90% of the problem. This statement is especially true when you deal with bug reports sent in by users in the field. A typical call from a user might be:
- User:
That database program you gave me is broken.
- Programmer:
What’s wrong?
- User:
Sometimes, when I’m doing a sort, it gets things in the wrong order.
- Programmer:
What command were you using?
- User:
The sort command.
- Programmer (patiently):
Tell me exactly what you typed, keystroke by keystroke, to get it to fail.
- User:
I don’t remember it exactly. I was doing a lot of sorts.
- Programmer:
If I come over can you show me the bug?
- User:
Of course.
Two minutes later, the programmer is in the user’s office and utters the fatal words, “Show me.” The user types away and the program stubbornly ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.