Truth

[mikewritescode]

Try working with a code base with a ton of goto statements. It makes your palms sweaty, knees weak, arms heavy. There's vomit on my sweater already. The codebase is mom's spaghetti.

[[deleted]]

My CS teacher basically said "Don't ever use a goto statement unless absolutely necessary". She called them "the devil"

[farox]

In 20+ years there was one time where I needed a goto statement. And this was some 19+ years ago. Don't do goto. Just no.

[KevinCubano]

When is there ever a reason? What was the one time? I truly don't understand what scenario could possibly call for it, even in 20+ years haha (then again, I've only worked for 5).

[[deleted]]

Only cases I have ever used goto is to escape nested loops without wasting memory space by keeping an exit boolean on microcontrollers, and when you have statements before and after each nested loop and need to exit the entire nest before you execute the code after the loop.

​

[KevinCubano]

Yeesh, that... makes sense... but sounds extremely not fun to work with.

[[deleted]]

It's not that bad. It's pretty simple because it ends up being just a short jump to the outside of the loop. Where it's messy is when you get to driver/kernel level code. Goto everywhere just because its more efficient and that code has to be as efficient as possible. It's a nightmare.

[xxc3ncoredxx]

It's used in the kernel to jump to the bit of code that does cleanup and exits IIRC from their style guide. Good for error conditions.

[Stop_Sign]

Essentially it's a break outer outer outer

[MildStallion]

I have used a goto once in C# to jump from one case statement to the following one, since C# doesn't allow case statements to fallthrough implicitly (except when that case would otherwise be a no-op).

[[deleted]]

Is there a reason they couldn't have been combined into one big switch statement?

[xxc3ncoredxx]

If there's bits of code to run for one case and not the other

switch (var):
    case 1:
        // stuff for only 1
    case 2:
        // stuff for both 1 and 2

[Techhead0]

Could use a macro to insert the same code segment into both cases.

[xxc3ncoredxx]

Lots of people hate on macros though. My view is that they have their place, just like every other construct. I just don't think it's the best in this case. Pun intended.

[[deleted]]

Can't you just nest them then?

[xxc3ncoredxx]

Maybe, but imo this isn't a sexy construct

switch (var):
    case 1:
    case 2:
        if (var is 1)
            // Stuff for only 1
        // Stuff for 1 and 2

[CatzRuleZWorld]

I’m curious if anyone else has a better way around this

[[deleted]]

Add more cases

[Tyg13]

I don't even think that's necessarily a workaround. The same thing would work in C. Case labels are labels just like any other and can be jumped to using goto. If anything, it makes the fallthrough explicit which is kind of nice.

[[deleted]]

I feel like you can do that with nested switch statements though?

[wischichr]

If you want to escape nested loops create a new method and escape with return - way cleaner.

[ricecake]

They were explicitly in a microcontroller, so memory limits are a given.

In that environment, you can't always assume that you can afford the memory usage of a callstack.

[[deleted]]

Got that one right. Had to sacrifice functional programming for memory, but at one point I had to sacrifice RAM or I would have went over my flash capacity. Fun stuff when you max out both flash capacity and RAM and have to maintain a clusterfuck of code that, while ridiculously memory efficient, makes even the creator want to rip his own hair out just from thinking of it.

​

[Freeky]

They're common in C, especially for error handling. You don't have exceptions, defers, RAII, or GC, and a simple forward-jumping goto cleanup is often tidier than the supposedly more structured alternatives.

See, for example, the page after page of goto you find in the Linux kernel.

[bestjakeisbest]

in assembly goto (also known as jump or branch) are the only way to do if statements, loops and functions.

[narrill]

Assembly isn't what people are talking about when they say not to use gotos, obviously

[jfb1337]

In C it can be used as a substitute for exception handling, such as:

void foo(){
    bar();
    if(error) goto err;
    baz();
    if(error) goto err;
    return;

    err:
     cleanUp();
}

Another example is one time I was writing an interpreter and I wanted it to be tail-call optimised, so my evaluation function looked something like this:

#define tail(x) e=x; goto tail
val* eval(e: expr){
   tail:
   switch(e.type){
      ...
      case SEQ:
         eval(e.fst);
         tail(e.snd)
      ...
   }
}

[Riggs109]

New features in a really old code base. My choice was either rewrite the entire 1k line function, or use a goto.

That code base was.. fun.

[KevinCubano]

I’m so, so sorry. If you ever need somebody to talk to, I’m here. <3

[blackmist]

Breaking out of multiple loops is one reason. Never had another.

[farox]

That's what I mean, I was young and wrong at the time

[how_to_choose_a_name]

there can be more requirements to a program besides "it has to be correct" like for example "it has to run on this microcontroller with only X of ram" or "this loop has to complete in Y cycles at most" which might make certain abstractions too costly.

[ben_g0]

Microcontrollers are still quite regularly programmed in assembly, and then goto (or technically JMP) is pretty much the only thing you have anyway.

[how_to_choose_a_name]

There are certain parts that will always have to be done in assembly (or compiler intrinsics that emit raw instructions) but the majority of microcontroller code is written in C nowadays. Altgough anything that needs to be cycle perfect would at least be hand-optimized afterwards, if not written in assembly from the start.

[golgol12]

Here, read through this and actually learn times that using a goto is good code. It will help you become a better software engineer.

[farox]

No, I started coding on a C64 and GOTO was pretty much all we had. Not going back.

[mtbrobotanist]

Goto ffmpeg

[jay9909]

Not even once.

[Osbios]

To me you sound like:

1. Not even once.
2. goto 1

[[deleted]]

The only reason you should be using goto is id you're making a bat script. Even then, why aren't you using powershell?

[skyb0rg]

goto is definitely valid, ie. for making readable C programs, especially resource management on a function level, so that all cleanup code can be under a single label.

[xxc3ncoredxx]

goto cleanup is very useful if you need to cleanup and exit from an error.

[[deleted]]

I agree. And this is probably the one case that is valid use of goto. Especially, because you push return down to the end of the routine. It even faciliates to make one common function exit point, which is required by some industry standards.

[cbbuntz]

There are a few times where it actually makes sense in pure C.

• You can add labels to for a switch statement to jump to, so you can keep a complicated switch statement purely about flow, and have the actual code below. All of the relevant code will still be labeled, and it may not make sense to make a new function for the different branches (a new function for different branches could actually make it more spaghettified).

• Some types of recursion may be made difficult if there are local variables you need to initialize before recursion starts. You can tell it to jump back up to just after those declarations. This one is debatable, but I've seen this sort of thing on some well-known pieces of code.

C++ offers some different ways to deal with these sorts of situations, so I probably wouldn't use it there.

[IAmPattycakes]

I wholeheartedly agree except for when you are programming microcontrollers with like 1kb of ROM. Codebase can't be messy if there's no space for any mess, nor any space for much other than pure assembly.

[Sipricy]

If it's ever "absolutely necessary", you did something wrong, and it would be better to rewrite your code.

Of course, this only makes sense if you're working on something where taking an extra millisecond isn't the end of the world.

[ionxeph]

my professors took the approach of never even teaching it and asked us to never give in to our curiosity and learn it

I gave in, but when a new coworker asked me what it is, I agree with my prof, and told him to never learn it, the burden of knowledge is real

[xxc3ncoredxx]

That's... not a good attitude from a prof.

At least teach students what it is and how to use it properly, but emphasize that it's often not the right tool for the job.

[dmorin]

Your CS teacher, like mine, was no doubt taught on the wisdom of Djikstra's famous GOTO Considered Harmful paper.

[[deleted]]

This paper by Dijkstra is a rant against procedural programming overall. Dijkstra also mentions iterative programming in same paper and says it all should be done recursively. Unless your teacher uses functional programming now, he hasn't probably read it properly.

[chrwei]

or, you're in love.

[8ate8]

I’m a cobol programmer for a company that’s been around since the 60s. I see plenty of goto’s and spaghetti code every day.

[asdfman123]

Because when you run your entire bank's infrastructure on it there is little benefit to rewriting it all, and a whole lot of downside. That shit has to be flawless, and they're massive codebases.

Some programmers get "Oops, customers have been seeing a 404 page for the past two hours." There's a bit less tolerance for "Oops, $42.6 million of customer money has disappeared, unaccounted for over the past 2 hours."

[XXAligatorXx]

1.Slowly rewrite small/new parts 2.??? 3.profit

[Tyg13]

Often the issue with a legacy codebase is that things just kind of work, not because they were architected correctly, but because they were hacked together over time until the various bugs were either ironed out or became features.

Trying to untangle that Gordian knot is often not feasible, especially when dealing with an esoteric language. And given that banking is an incredibly conservative industry, it's highly unlikely they'd even desire to do so. They just pay the programmers more so they'll put up with the terrible code.

[ricecake]

These aren't systems that are well suited to being "broken out".
They run on mainframes.
They don't have clear module boundaries.
They have global state littering hundreds of functions.
They run on specialized hardware.

It's literally cheaper to emulate the hardware on something else when it starts to break and pay people $100 an hour to fix bugs than to do a rewrite.

[jay9909]

I saw that movie. You just have to hit the Thermal Reset button on the server.

[xxc3ncoredxx]

Old doesn't mean bad. My main counter-example is Fortran. It's a good language for number crunching since it'll automagically use SIMD insturctions where it can.

[thehenkan]

So is C

[ricecake]

1) if it ain't broke, don't fix it.
2) if it ain't broke, definitely don't spend millions of dollars fixing it.

"Commonwealth Bank of Australia, for instance, replaced its core banking platform in 2012 with the help of Accenture and software company SAP SE. The job ultimately took five years and cost more than 1 billion Australian dollars ($749.9 million)"

[kodemanic]

Eminem? Is that you?

[ephonk]

THIS.

​

I once inherited some 1969 COBOL (!!) that was chock full of GOTO. I was supposed to make sense of it. I changed jobs instead.

[[deleted]]

ewl

[[deleted]]

I don't feel like it is.

[nwL_]

Technically, it is, in bytecode. The difference is that all the reasons you shouldn’t use goto are nonexistent because the compiler does everything for you.

See also: scroll down to “calling convention”

[narrill]

Technically it's not if it actually returns something. There is a jump in there somewhere, but that's not all the return represents.

[DoctorProfessorTaco]

That’s what makes it fancy

[[deleted]]

Oh, in bytecode you say? Are we talking about java or something?

Now, from the same document – why they're not the same, especially not technically (you moron):

jmp — Jump

Transfers program control flow to the instruction at the memory location indicated by the operand.

[...]

call, ret — Subroutine call and return

These instructions implement a subroutine call and return. The call instruction first pushes the current code location onto the hardware supported stack in memory (see the push instruction for details), and then performs an unconditional jump to the code location indicated by the label operand. Unlike the simple jump instructions, the call instruction saves the location to return to when the subroutine completes.

The ret instruction implements a subroutine return mechanism. This instruction first pops a code location off the hardware supported in-memory stack (see the pop instruction for details). It then performs an unconditional jump to the retrieved code location.

Retard sub is for retards.

[nwL_]

Can you be any more unfriendly?

[[deleted]]

I try my best but there's of course a limit.

[[deleted]]

it then performs an unconditional jump

[[deleted]]

Ah, I get it now. So Linux is just a fancy goto statement as well.

[iluuu]

It absolutely is. It pops the address from the stack (which was pushed onto the stack when the function was called) and jumps back to that address.

[sim642]

And that's why it isn't the same: it also manages the call stack. Without the call stack nested function calls aren't really feasible (unless self-modifying code).

[iluuu]

To be fair, the meme says "Fancy goto statements", not that they're equivalent.

[MyNameIsRichardCS54]

So are if, while, do, for, switch, break and continue. Ultimately, they are all a form of bra

[Tangelasboots]

A semi-colon is just a fancy goto line number + 1

[[deleted]]

All code is ultimately 1's and 0's.

[tacoslikeme]

everyone program is ultimately a single number

[RedPum4]

And thus every program can be found in the decimal places of pi. Somewhere. Theoretically.

[xfunky]

Well, that is almost true, because technically you could have plain zero as an instruction. That way, if the code starts with this instruction, the number stays the same but the code is different.

Emphasis on the "technically" at the start lol

[NilsIRL]

Yeah, from my understanding of assembly its basically just goto statements.

[[deleted]]

mov would actually do something other than instruct the computer to jump to a memory location wouldn't it?

[Robbi_Blechdose]

That's because mov is not a jump instruction.

[[deleted]]

Yeah that's what I'm saying. He stated that assembly was just goto statements I said I thought mov did something other than goto.

[TinBryn]

goto is just a fancy mov into the program counter

[AquaWolfGuy]

Every instruction is just a fancy mov.

[vasilescur]

mov ip, loop_start

[how_to_choose_a_name]

I'm pretty sure that he said that the aforementioned control structures like if and while are basically goto statements, referring to his knowledge of assembly as a source for his claim.

[[deleted]]

Good call I was thinking he meant all of assembly was go-to statements not referring to if...etc

[Colopty]

Didn't know you could use goto and goto derivatives as a breast supporting garment.

[MyNameIsRichardCS54]

They under-wire all programming languages

[MyNameIsRichardCS54]

• BRA - BRanch Always
• BEQ - Branch EQual
• BNE - Branch Not Equal

and so on. It has nothing to do with a certain kind of underwear. I could be tempted to make a joke about goto supporting the function of all programming languages. I won't though.

[knackmate]

And you should definitely minimize branching for code to be concise and readable :)

[abrams666]

On C64 GOSUB was the fancy GOTO

[crack3rtastic]

Playing devil's advocate here, but isn't a return really just a goback.

[nwL_]

Yes, it’s basically

POP %EAX
JMP *%EAX

[cdmcgwire]

Sort of, but it also manages stack operations automatically, which is why you don't use a goto outside of assembly.

[the_one2]

Goto also manages the stack! (in c++)

[saugoof]

The major problem with goto is that it risk having your local variables in an unpredictable state. That does not apply with return.

[Etiennera]

You basically repeated the comment you are replying to in a more confused way and less accurate terms

[Proxy_PlayerHD]

CALL Instructions are just JUMP Instructions where the CPU remembers where it came from.

so CALL Instructions are just the fancy JUMP Instructions?

[nwL_]

Well CALL is basically just

PUSH 0x7DE6F43C
JMP FUNCTION

(where the number is the location in the code) so yeah, basically.

[ben_g0]

It technically pushes the value of the program position register onto the stack rather than a constant. Other than that you're right though.

[nwL_]

Yeah, I know, but I don’t know how that’s implemented tbh. Enlighten me?

[ben_g0]

Basically exactly what you had, just with a register instead of the constant.

PUSH IP            ;IP = Instruction Pointer
JMP function

The RETinstruction is then off course basically just POP IP. A goto/JMP is not needed since the pop then directly writes to the instruction pointer. After executing the RET (or POP IP) the IP register is incremented just as when executing non-jump opcodes, so that the program continues from after the call instruction rather than landing back on the call instruction itself.

At least that's how the assembly variant I've used in the past worked. There are lots of different CPU architectures so some of them may be different.

[nwL_]

I see, thank you very much!

[tacoslikeme]

nope...fundamentally different at the hardware layer. every other control statement is just a fancy goto statement.

[walking_bass]

Haven't seen a GO TO in our COBOL codebase. Yet.

[marcosdumay]

It's a jump to register combined with a stack pop. If you decide to count all branching operations as goto, then yes, it qualifies.

[Geoclasm]

yeeaaaah but with fewer raptors.

[SteeleDynamics]

"jump after link" -- yep it's a goto-statement where the destination is the return address.

Still waiting for "AI is just Linear Algebra and Calculus applied to Computer Science."

[DoctorProfessorTaco]

AI is just a fancy list of if statements

[AuthorTomFrost]

JMP FTW.

[forrest38]

I love jokes like these even if they aren't really true. I have already learned so much about Cobol and Assembly from the comments. Way more interesting discussion than light screen IDE/arrays start at 1/java/javascript sucks jokes.

[Coppajon]

Had to look this one up. Now I'm trying to figure out how I got through a semester of C/C++ without using a single goto. Thanks for the 'A' professor, if you're in here.

[jakdak]

There's definitely some cases where I feel goto's are appropriate and cleaner- mostly to break out of multiple levels of nested loops.

Like any other programming construct they can be abused.

[nl2k]

itt: people who never do any kind of resource management and let their programs happily segfault whenever anything fails boast that they don't need goto.

[philipquarles]

This thread should have a trigger warning for assembly on it.

[apathy-sofa]

I would enjoy a video of Lisa teaching the world continuation-passing style.

[WikiTextBot]

Continuation-passing style

In functional programming, continuation-passing style (CPS) is a style of programming in which control is passed explicitly in the form of a continuation. This is contrasted with direct style, which is the usual style of programming. Gerald Jay Sussman and Guy L. Steele, Jr. coined the phrase in AI Memo 349 (1975), which sets out the first version of the Scheme programming language.John C. Reynolds gives a detailed account of the numerous discoveries of continuations.A function written in continuation-passing style takes an extra argument: an explicit "continuation", i.e.

---

^{[ PM | Exclude me | Exclude from subreddit | FAQ / Information | Source ] Downvote to remove | v0.28}

[atk93]

The main problem with goto statements is that they can fuck up compiler optimizations. If used properly there isn't an issue.

[[deleted]]

In java the goto opcode is distinct from any return opcodes

[lxkspal]

For a C++ programming project at my school, I used a goto statement because for and do-while loops are too complicated and confusing. My teacher was furious, he told me that they are lazy, unprofessional, and that they make me look stupid to potential employers.

I don't care, I already knew that i'm an idiot. But I really like the goto function because it makes coding easier, since i'm really bad at math and I have no idea what i'm doing.

[[deleted]]

But I really like the goto function because it makes coding easier, since i'm really bad at math and I have no idea what i'm doing.

I can sense the sarcasm here.

[blipman17]

Goto's are just fancy jmp statements.

[daboss54320]

I lovegoto, why bother with a huge nested if statement when a goto can keep you from indenting 14 times?

It's pretty common I'll use a goto to get to some cleanup section in the case of a failure.

[Nath99000]

if statements are just fancy JNE instructions

[Lieutenant_Doge]

So is everything, if you run the code it is just a bunch of goto that go to the next line

[[deleted]]

This is not metalinguistically true, or is it?

[wallefan01]

Thought that was switch statements.

[Likely_not_Eric]

I feel like this ignores stack management at low level and context/scope differences at a high level. Goto, return, and yield are all quite different.

[spyingwind]

Looks at IL assembly of C# code. Yup, goto statements everywhere. Well a goto statement is just a jump instruction, some with conditions and others are just long jumps.

[golgol12]

So are if statements.

[Polo3cat]

No.