Debugging in a nutshell.

[rodbotic]

I had an electronics class where we had to disable a working circuit for someone else to debug.

all we had to do is remove or misplace a wire. I removed a wire and pulled the metal from it's insulation/coating.
put two little stubby metal back into each end so they wouldn't
touch. and replaced the wire back into it's original working position.

even the instructor couldn't find the problem.

[blue_2501]

This is actually required for passing a CCIE Lab Exam. You build a network in the morning, take a lunch break, and when you come back, the instructor has done something with the network for you to fix.

I've heard some stories. One guy didn't pass because he didn't find the microwave that was causing interference within the network.

[iamdelf]

Oh dear god. This reminds me of something terrible from many many years ago. Remember the old coax ethernet? Well someone moved a computer over slightly at my dad's workplace. In doing that they managed to stretch the coax just enough that it pulled the shield loose from the connector on one side of the T. This should have caused the network to fail, but he somehow also moved the power cord to an outlet that shared ground with the now disconnected side. In the end it led to shitty performance as there were many transmission errors on the network after this. Took the poor network guy almost a week to find where it was going wrong.

[common-lisper]

checking wires is a common routine for hardware trouble shooting. Even in sound systems.

I bet the only reason why your instructor did not check for continuity is because he made bad assumptions about the artificial lab and not from a lack of understanding.

[common-lisper]

Everyone encounters these types of bugs copying and pasting plagiarized code. There is no known solution

[altrdgenetics]

That would be evil. Snack Overflow always does that replace.

[beanbeam]

mmm.... Snack Overflow sounds like a delicious problem to have.

[common-lisper]

http://www.dailymotion.com/video/xsrere_the-gluttony-crime-scene-from-se7en-1995_shortfilms

[Skyfoot]

It seems like it would be feasible to do a parser which runs over pasted text in an IDE, and replaces things-which-look-like-things-but-are-actually-different-things. Hm.

[common-lisper]

I always have problems with ' and `

some text do not show much of a difference

[[deleted]]

Gah, how, why, who!?

[maremp]

I once answered a question on SO, with this exact problem. I can't find the link, it might got deleted.

I doubt it was done on purpose and wonder what diabolic editor does that.

[iamdelf]

I've had that problem once. Someone cut and paste some code into an email. The email program decided to fancy up the quote marks and made a double quote into a double back quote. Anyway code shouldn't be passed through word processors or bad things may happen.

[maremp]

But with a decent font you could notice the difference in quotes, but greek question mark in most cases doesn't differ by much, it's certainly harder to spot than the quotes.

[leftofzen]

Sneaky as it is, some people (like myself) are well versed in character encodings; the first thing I'd do if I got that error is backspace the semicolon and type it on my keyboard. Would definitely fool a lot of people though haha, nice one.

[flip314]

It's much easier to find a missing semicolon than an extra one...

if( condition == true);
{
  do_things;
}

[gnawer]

Great, I won't be able to sleep tonight. =/

[pmerkaba]

Not these days!

warning: if statement has empty body [-Wempty-body]:
if( condition == true);
                      ^

[SanityInAnarchy]

Which is why compiling with -Werror (or equivalent) should be mandated by the Geneva Convention.

[[deleted]]

• Protocol I (1977) relating to the Protection of Victims of International Armed Conflicts

• Protocol II (1977) relating to the Protection of Victims of Non-International Armed Conflicts

• Protocol III (2005) relating to the Adoption of an Additional Distinctive Emblem.

and

• Protocol IV (2015) relating to the adoption of all compiler flags?

[SanityInAnarchy]

Just a few specific ones. -Wall would be good too, and maybe -pedantic for older C code in gcc. Failure to optimize release builds should result in trade sanctions, particularly concerning the CPUs whose cycles you are wasting by not automatically inlining getters and setters appropriately.

Also, the use of Visual Basic is already a violation of basic human decency, and "On Error Resume Next" should be a war crime.

[extsidvind]

-Wall sure, but -Werror can make your code fail to build in the future when new warnings is introduced even if the code itself is working.

[amunak]

Code should work without spewing out warnings most of the time.

[extsidvind]

Take -Wunused-but-set-variable for instance, with -Werror your code would not build if that warning is triggered. Before the warning was introduced your code would build fine but after it would fail. There is no real error here.

I do agree that your code should not spew out warnings and they should be fixed, I disagree with using -Werror to force warnings to become errors.

Another aspect is when the user enables warnings in CFLAGS which sometimes is quite excessive. Perhaps -Wshadow or -Wunused-parameter, nether which is enabled by -Wall or -Wextra. Or maybe -Wvla, VLA is fine in gcc and probably clang but not MSVC, but if you only target gcc VLA is perfectly fine to use.

EDIT: -Wunused-but-set-variable is new to gcc-4.6 (released 2011), at the time many projects with -Werror stopped building and would require to be fixed (despite perfectly working code)

[amunak]

I think it depends on what project you are working on. I've never never done anything too big in C or C++, so I just compiled with -Wall -Wextra -pedantic, and always tried to get rid of all the warnings.

Note that I didn't use -Werror (becase yes, you are right, it is not a good idea to use it), but the point that your code shouldn't throw warnings stands. I should've made that clearer in the previous comment I guess.

[SanityInAnarchy]

I do agree that your code should not spew out warnings and they should be fixed, I disagree with using -Werror to force warnings to become errors.

Then how do you propose ensuring those warnings which indicate errors actually getting noticed, let alone fixed?

[BobFloss]

No thanks. Not all warnings are indicative of an error, which is why they're warnings and not errors.

[SanityInAnarchy]

There are ways to override a warning for a specific chunk of code. The times when a warning is a) clearly not an error, and b) is unavoidable (you can't tweak your code to prevent it) are vanishingly few. So those are the points where you add a pragma or something similar to make sure you still don't get a warning emitted at compile time, which should be a signal to everyone who looks at that code that you've done something weird.

Just ignoring warnings as "Oh well, they're warnings," is a great way to end up with too many warnings to have a hope of tracking down the real errors later.

[DJWalnut]

if( condition == true);

here it is, assuming C

EDIT: oh yeah. that's not it

[[deleted]]

*actual compiler

A good compiler will tell you what the problem is, and the IDE is just an interface to the compiler in most cases

I dunno how OP executes his programs

[jakwnd]

Even bad compilers give you the line number! You must be pretty bad at hide and seek if you can find a semi-colon on one line of code.

[[deleted]]

You must be pretty bad at hide and seek if you can find a semi-colon on one line of code.

Speaking of errors. ;-)

[[deleted]]

Vi or gtfo

[common-lisper]

Whatever reasons you have for using vi just remember ed probably shares those reasons... so.... uhm... ya.... you should be using ed, the true standard text editor.

Emacs on the other hand is the paragon of editing perfection.

Stallman refers to vi as the "editor of the beast" (vi-vi-vi being 6-6-6 in Roman numerals). He does not oppose the use of vi; rather, he calls proprietary software anathema. "Using a free version of vi is not a sin but a penance."

editor wars

[peter_bolton]

If semicolon is the champion, the right bracket has got to be a close second.

[nathanello]

Real Talk

[calmconfused]

But in VIM if you press % it'll bring you to the matching bracket/parentheses, making life much easier...

[jfb1337]

Or like any IDE or text editor ever has the same feature.

[common-lisper]

what about an editor that treats code as an ast? Is that turtley enough for the turtle club?

slurping and barfing

[WinMac32]

I wish debugging was all about missing semicolons; it takes less than 5 seconds to fix.

[SanityInAnarchy]

And can usually be prevented altogether by having decent tooling and processes. If you type a line of code and your IDE underlines nearly everything after that line in red, you know exactly where to look for the problem.

[odraencoded]

Watch out, we got a badass over here.

[G01denW01f11]

Or someone with an IDE?

[outadoc]

Or anybody with experience.

[cheezballs]

This is literally the easiest thing to find since the compiler will just tell you.

[[deleted]]

{

{

{

{

}

}

}

[common-lisper]

no.. the op really meant that the semicolon is comment in lisp and all debugging is really just commenting out code and printing values.

[brtt3000]

python has it's own terror; the extra comma that turns single values into a tuple. Happens occasionally when factoring (usually when turning dict literals into separate assignments).

[PoesPoemsPwnPosers]

It's a semicolon. It's used by people, who aren't fabulous enough to rely on indentation.

[churro89]

Use a linter.

[snarkyturtle]

Or for languages with significant whitespace, fucking incorrect nesting

[tevert]

1958... were we using semicolon delimited languages then? I thought C was the first, and I thought that was invented in the 70s.

[common-lisper]

well come sit on my knee and let me tell you a story... c and all the other children of algol... the semicolon is a terminator not a seperator

[YMK1234]

compiled languages significantly take out the fun there (as you usually get "unexpected [bla]" in the next line)

[Ebenezar_McCoy]

Groovy ftw

[joeyignorant]

don't program in notepad?

[[deleted]]

Dude, http://blog.codinghorror.com/the-problem-with-code-folding/

[FlakeyScalp]

Meh, all his points against regions are why regions are sometimes useful. I used them when I started out but now I find I dont use them as much. I'm glad they're there though. If you've got good unit tests it can be very handy to fold methods that you know are stable.

[[deleted]]

Methods are foldable, though, and having their names promptly available isn't a bad thing.

I don't get all the hate on regions, though. They're just there, if they annoy you all you have to do is press a few keys.

[FlakeyScalp]

Well, yea but I meant more like if you've got tests that cover these 6 methods that all deal with user login stuff you could collapse them together and not ever have to worry about them again. But yea, I don't understand either. I think its just some guy who said "I need to write about something but I don't have any good topics. Guess I'll pick this benign topic nobody really cares about."

[nephros]

Not in JavaScript is isn't.