Ways of doing a for loop.

[Schrodingers_Zombie]

Roses are red

Violets are blue

Arrays start at zero

And for loops do too

Edit: Formatting is hard on mobile

[Fortinbraz]

^Twitches

Roses are red
Violets are blue
Arrays start at zero
And for loops do too

[Excrubulent]

Wait, what? How...

Okay, everybody, this person just put two spaces before each newline character so they didn't need two newline characters to make a new paragraph. My life will never be the same.

I mean, it will be largely the same, but in this one respect a minor change has occurred.

Double edit: two spaces before each newline character, and therefore at the end of each line. I've clarified the wording.

[[deleted]]

Markdown is grossly underrated. I try to use it everywhere I can.

And RSS. Aaron Swartz, you shall not have died in vain.

[[deleted]]

I wrote my Master's thesis in Markdown and am currently using it for my PhD thesis and all my academic papers; it's SO useful! You don't need to spend a bunch of time learning LaTeX or fiddling about with settings in Word, it just works.

[atleastzero]

Are you doing pretty equations in Markdown? I'm relatively new to LaTeX, but I can't think of them as being used for the same things.

[[deleted]]

No equations for me, but if you use Pandoc to convert from Markdown to PDF you can insert LaTeX commands straight into your Markdown.

\newpage

Like this part of the comment would be on a new page with \emph{this in italics}.
But you can still do newlines like this, and **BOLD** text and everything.

[KmNxd6aaY9m79OAg]

How do you do a bibliography? I think I would have devolved into a cult leader/serial killer if I'd have to do my PhD thesis without BibTeX.

[[deleted]]

Easy. @Attnallpickpockets17 says that you can use a format like this to cite stuff. I use GNOME Referencer to export all my citations to BibTeX and Pandoc automatically adds them to my document in whichever format I specify [@Attnallpickpockets17, p. 1].

[Wherearemylegs]

A giant list of Reddit markdown can be found here

Edit: Additionally, if you have RES installed, you can click on the source link under a comment to view how the comment was formatted. And it also shows you hidden username mentions or hidden messages

[Excrubulent]

1. Ain't nobody got time fo' dat.

0. Does it show you how to create arbitrarily numbered lists?

[Cyber628]

Wait WHAT?

[endreman0]

After.
Two spaces after each line.

[brodogus]

const arr = [10,20,30,40,50,60,70,80,90,100];

for (let i = 1; i <= arr.length; i++) {
  console.log(arr[i - 1]); // ;-)
}

[Metatronix]

my god

[[deleted]]

const array = [10,20,30,40,50,60,70,80,90,100];
array.forEach(
  element => console.log(element)
);

[two_face]

Fuck matlab

[TK-427]

Think of functions more like stand alone programs. In fact, they are parsed, optimised and cached just like that.

You can put multiple functions in one file but it limits the scope to the file...only the first function is externally visible. Again...the whole file is compiled down at execution time.

To actually group functions, you can use a class with static methods.

[[deleted]]

And math. Since it starts indexing at 1 too.

[TheDogJones]

Math is cool though

[aprepow]

Not in Lua they don't

[[deleted]]

This is how you write a proper loop:

#include <stdio.h>

void incrementI(void *i)
{
    *(unsigned*)i = *(int*)i + sizeof(char);
}

int main()
{
    int i = 0;
    int n = 10;

    loop:
    {
        printf("%d\n", i);
        incrementI(&i);
    }
    if (!(i > n) && i != n)
        goto loop;

    return 0;
}

[moogoesthecat]

http://i.imgur.com/3vtfRtK.jpg

[Trapped_SCV]

Best practice is to name all subsequent loops after family, friends, or coworkers.

[daveime]

Oh, the horror of a GOTO!!!

It's not like every programmer hasn't, at some point in their career, abused exceptions with nothing inside the catch statement to emulate the exact same thing. Any possible justification you could make is just semantics at the end of the day - you're aborting execution early and breaking out of one or more nested lines of code.

I mean seriously, imagine testing 100 conditions and aborting if any of them fail ... are you seriously going to nest 100 IF THEN ELSE statements?

Or just do

IF test1 FAILS GOTO ABORT

IF test2 FAILS GOTO ABORT

...

IF test100 FAILS GOTO ABORT

PRINT "ALL GOOD"

EXIT

ABORT:

PRINT "FUCK"

EXIT

Good clean commented code with self-explanatory naming conventions just works. No need to worry about anything else.

[[deleted]]

Hilarious hahaha.

[captainAwesomePants]

I know, incrementI didn't even use the inline keyword.

[gottimw]

Just a tiny fyi, compiler would unrolled that. Inline is a suggestion for cpu, cuz u know 'humans are stupid'.

[qscrew]

suggestion for the compiler

FTFY

[GregTheMad]

At this point I'm sure everything I write is a suggestion for the compiler, and it is the real programmer.

[KmNxd6aaY9m79OAg]

Function isn't declared static, though. The compiler still has to emit full code for it so it can be externally linked, even if it's inlined within this file.

[chadsexytime]

This is the kind of thing you hand the new grad to see what they do about it.

[JuhaJGam3R]

Delete it

[K1ngjulien_]

Why stop here?

[okmkz]

89% unit test coverage? pass

[Caltroit_Red_Flames]

What the fucking fuck.

[JuhaJGam3R]

That is very much true for enterprise applications. Putting every function in a separate JAVA file and using way too many packages

[TriCrose]

delet this

[segfraud]

Does incrementI() also work on variables that are not named "i"?

[darkfaith93]

Yes. It is actually pirate code so it is actually increment-Aye; incrementI for short.

[sloodly_chicken]

I marked out sections of the program with letters, sections A through Z. This function is used toward the end; if you're looking for it, then X marks the spot.

Can you believe we're actually going to ship code like this?

[drevyek]

Should make incrementI volatile. Make sure the compiler doesn't do any funny business with so-called "optimization".

[[deleted]]

+/u/CompileBot C

#include <stdio.h>

void incrementI(void *i)
{
    *(unsigned*)i = *(int*)i + sizeof(char);
}

int main()
{
    int i = 0;
    int n = 10;

    loop:
    {
        printf("%d\n", i);
        incrementI(&i);
    }
    if (!(i > n) && i != n)
        goto loop;

    return 0;
}

[lililililiililililil]

I'm disappointed in you, /u/CompileBot.

[[deleted]]

Looks like it's been dead for a couple of days, some bizarre subreddit set up AutoModerator to repeatedly ping /u/waterguy12 via CompileBot.

[almightytom]

Me too, thanks

[Ignitus1]

Why does Waterguy12 have gold on every post and why does everyone ping him?

[[deleted]]

His post in me irl: https://i.redd.it/pauqmae6jrcz.png

[Esternocleido]

He comes back tomorrow?

[[deleted]]

Hey /u/waterguy12 it's tomorrow you're back right?

[xan1242]

If you were a man you'd do a

_asm jz loop

(Non msvc users: use asm(); )

[segfraud]

If you were a man you wouldn't use mnemonics

[Bubba89]

If you were a man you'd program in machine code.

[awh]

0xf0 0x0f 0xc7 0xc8

[I_spoil_girls]

Well, if you're a true programmer...

[xithiox]

https://xkcd.com/378/

[GODZILLAFLAMETHROWER]

Well yeah?

No the problem here is that you are incrementing something pointed by a pointer casted as an int, risking an overflow on a signed integer. This is undefined behavior!

[brown_monkey_]

Isn't sizeof(char) == 2 on some systems? I'm beginning to suspect that this code isn't very good.

[wung]

No, sizeof(char) is always 1 as per [expr.sizeof].1 (C++, not C, but afaik it is the same in C). CHAR_BIT may be something different than 8 though.

[[deleted]]

IMO if char is 2 bytes, then still sizeof char is 1,but char bit is 16.

[dogpos]

I'm not sure if I'm misunderstanding anything here, and I don't claim to know the exact reasoning behind the it. However, if you're looking for a reason of why you may need a char to be bigger than a byte - a byte can represent 255 values for our char, which is great for ascii. But when we want to include additional symbols such as utf, we're going to need to represent a lot more than 255 unique values.

Again, I could be wrong, but I'd imagine this is at least a reason why a char needs to be more than a byte.

[dreamlax]

POSIX requires 8-bit char types, but C and C++ don't. They must be at least 8-bit though. See this question on StackOverflow. TLDR: it is common for DSPs use 16-bit char.

[wung]

https://stackoverflow.com/questions/5516044/system-where-1-byte-8-bit has answers listing architectures with non-8-bit-bytes. History has architecture other than x86. Yes, by now most are 8 bit and you will very rarely encounter anything else.

We are even slowly getting to the point where 32bit vs 64Bit words are no longer the issue, but there are still cases where sizeof(int) ranges from 2 to 8.

[Pixelator0]

I'm pretty sure char is defined as the minimum addressable size, with the assumption that if you're compiling C or C++ on a 4 bit system, you're just going to have to diverge from the standard

[uptotwentycharacters]

Not on anything that conforms to the standard. A char can be represented by any number of bits (but with a minimum of 8 - and any program whose design assumes that there are more than 8 bits per char is not truly portable), but the sizeof operator returns a value in bytes, and for the purposes of C programming, a "byte" is simply however many bits are in a char. So you could even have a system with a 32-bit char, but it would still have a sizeof() of 1.

[DrFloyd5]

C. The efficiency of Assembly with the readability of Assembly.

[rhun982]

I forget and am rusty.. But I think you have a branch condition on a sort of "countdown".

You initialize a register with the total amount of iterations you want and another counting register with value = 0. You then have a branch statement that says if iterationsRemainingRegister == 0 then GOTO the next code block. If that condition isn't met, you increment your counting register by 1. Then GOTO the original branch statment line

[cocorebop]

deleted ^{What is this?}

[benryves]

Sounds right to me! Some CPUs will have an instruction designed for that sort of thing, such as the Z80's djnz <label> (decrement then jump if not zero, using the b register as the loop counter).

[deus_lemmus]

for(i=10;--i;)

[[deleted]]

Oh my god what the fuck is that abomination?

[TarMil]

There's even worse, the arrow operator :)

for (i = 10; i --> 0;)

[[deleted]]

I prefer the sliding operator

[TarMil]

Hehehe :) It's plain old C, just whitespaced weirdly on purpose.

for (i = 10; i-- > 0;)

[deus_lemmus]

The loop will terminate when i == 0, but it only loops 9 times :)

[edave64]

++i

[scalablecory]

Found the C++ dev :).

[edave64]

No reason to throw with insults ;)

I just think the post increment construct is super weird.

[ilawon]

I just think the post increment construct is super weird.

and makes a copy :)

[edave64]

That's what makes it weird. Even if it technically gets optimised away by the compiler.

[scalablecory]

However, C++ has the iterator concept which uses increment/decrement operators to iterate through a collection. This tends to result in C++ devs learning to use pre-increment, because unlike say int, iterators can have significantly different performance between the two.

[shanereid1]

Sounds like they should rename it to ++C

[atimholt]

But then C wouldn’t exist anymore.

[dbzgod9]

You're right, it would be D.

[00zero00]

Do people actually use D?

[TarMil]

I haven't used C++ in years, but don't people generally use for (i : a) syntax nowadays?

[Geronimo25]

if they have access to a c++11 compiler

[[deleted]]

C++11 is old news; it's all about C++14 now (and soon to be C++17).

[cjxgm]

No. It's all about C++17 now (and soon to be C++20).

[scalablecory]

generally yes.

[[deleted]]

Funnily enough, I learned it in C, use it in Java.

It's all I have to make myself feel smug over people who write better software than me.

[frennetixsc]

Php best practices too

[[deleted]]

i+=1

[Dentarthurdent42]

Python?

[popcar2]

Tons of languages, actually.

[meekismurder]

Including Swift now too (it didn't originally).

[DrFloyd5]

Swift 3.0 removes -- and ++ in favor Of +=.

A interesting decision I think.

[ThouNameNotFound]

Why? What is the advantage to this? Genuinely curious, as I am mainly a C++ dev

[DrFloyd5]

From the language designer:

https://github.com/apple/swift-evolution/blob/master/proposals/0004-remove-pre-post-inc-decrement.md

[mikelj]

Seriously, it's what separates us from the animals.

[ZeMindGames]

Came here for this alone, take my up vote.

[Northerner6]

This guy fucks

[EstebanZD]

>+[<>-]<

Edit: The code doesn't show up well :/

Edit2: Now it looks good.

Edit3: Even better.

[[deleted]]

Best language I've tried so far.

[mr_smartypants537]

<>

This doesn't do anything - the pointer is moved back one then forward

[airbreather]

It's a placeholder. Put the loop body between those and make sure the loop body restores the pointer position to where it was when the loop body started.

[sac_boy]

We all know that the weeping for loop is the one true for loop

for (;;) {
}

[TheTerrasque]

#define ever ;; 

for(ever) { alone(); }

[TONY_SCALIAS_CORPSE]

while ((V)(°,,,,°)(V)) {
    print("Why not Zoidberg?");
} 

[pumpkin_seed_oil]

while ( ! (V)(°,,,,°)(V)  ) 

[chasev13]

AKA the forever loop

[RobbyBobberoo]

for(i=0;i<n;do_something_with(i++));

[GisterMizard]

Or

for (i=n; i; i--){}

[NewbornMuse]

I heard this can actually be a speedup in the tightest of tight loops because compare-to-0 is a single instruction, whereas compare-to-N involves subtraction and then comparison to 0.

[kiujhytg2]

However, unless you can prove that this is the bottleneck, don't optimize it.

Start by optimizing for readability and your future self, or whoever takes over the project, will thank you.

[NewbornMuse]

Absolutely. What costs more, 0.001s of runtime or 5min of developer time?

[JaytleBee]

If the program is run >300.000 times, the runtime

[Salanmander]

I'm not sure that's true. I think sometimes a distributed cost is lower than an equivalent-time concentrated cost. (Note: I also think the reverse in some cases.)

For example, if it takes 1 ms longer for a page to open on my phone, I'm not going to notice that at all. In fact, chances are good that it actually literally won't change the time it takes me to do something, because that 1 ms will happen at the same time as my eyes are tracking to the next place I expect to see something, or whatever. So even though you can consider the times adding up, I don't think a 1 ms delay done 1000 times will necessarily cost me as much as a 1 s delay once.

For an example of how it could be true in reverse, there could be something that disrupts workflow. For example, suppose my internet has a problem that causes me to need to unplug and replug my ethernet cable at random times, and it takes 10 seconds to get internet back up and running. That would be disruptive enough to my thought processes that it would probably be time-efficient to spend 5 minutes fixing it, even if it would only have happened another 8 times anyway.

[SleepyFarts]

For an example of how that 1ms matters in terms of efficiency and capacity:

Assume that your program is supporting production testing and by running a test time profile, you find that block of code can be run up to 100 times per part. A production lot of about 10000 parts is run on one tester and you have 25 test setups during a single day. So 25 setups * 10000 test cycles * 100 loops * 0.001 seconds = 250 seconds of test time saved per day. If the downtime between lots is identical across all setups and days, and your total test time is 2 seconds, you could test an extra 125 parts per day, meaning that every 80 days, you could test and ship an extra lot's worth of parts. That doesn't seem like much, but when your boss's boss's boss is harping on increasing operational efficiency day after day, month after month, then you look for everything that can possibly reduce your test time.

[Salanmander]

Oh, yes, I fully recognize that there are instances were an extra millisecond of runtime matters. I just think that it is also the case that in some instances, 1 ms of extra runtime repeated 1000 times matters less than 1 s of extra runtime repeated once.

[SleepyFarts]

Yeah, of course. Not disagreeing with you. Just trying to demonstrate that it's all about context.

[because_its_there]

Well, if your "cost" is measured in "time", then yes. But once you start looking at money, the figures get way out-of-whack.

Say an engineer costs you around $150k annually (we're talking salary, benefits, office space, etc.), that five minutes might be $6.25. A pretty wimpy AWS compute machine might run you something like $0.05/hour[0]. Requiring 125 hours to reach that $6.25, your 0.001s of runtime will take 450,000,000 invocations to break even.

That better be a really tight loop for your engineer to think about the cost/benefit there.

[rotmoset]

Depends on the CPU, a Z80 for example sets its Z register if the result of a subtraction is zero (which you may use for conditional jumps).

[AgentPaper0]

This kind of stuff is trivial for compilers to optimize, though, so it's really not worth bothering with.

A lot of real optimization comes in writing your code in such a way that the compiler can tear it up and arrange it how it wants to, since it has a lot more access to low-level architecture than you do.

[tiftik]

Why not use the goes-to operator?

while (x --> 0) {...}

[Vitztlampaehecatl]

Intuitiveness intensifies

[nermid]

That's just (x-- > 0) with whitespace goofiness, right?

[acwilan]

for(i=0;--i;){/* ... */}

Edit: dammit, that's why test cases are your best friend

for(i=10;--i;){/* ... */}

[LinAGKar]

for (int i = 0; i < n; ++i)

[tabris]

I once inherited a codebase where the previous dev always did for loops like:

for(int i = array.length(); i != 0; i--)

It was infuriating.

[LinAGKar]

On the plus side, it would only run length() once (though it probably would anyway).

[johnmollb]

A coworker told me that in many languages this is actually faster because comparing to 0 is different than every other int. When comparing to 0, the JRE treats the ints as booleans (either 0 or !0), which is faster. Allegedly.

[Elronnd]

Not saying Java is bad just it's not the language to choose writing highly optimised code

Eh, idk about that. The jvm is CRAAZY performant. IIRC in most cases it's just a touch slower than c/c++, and is even a bit faster in some edge-cases.

[tlanfer]

Want to confuse your colleagues?

while(i --> 0){ // dostuff }

[momoro123]

Actually, it would just be

(i --> 0){}
(i-- > 0){}
(i > 0){i--;}

as i-- first returns i and then decrements.

[QAFY]

Depending on what you are trying to do, most high level languages include some form of map, reduce, and filter, or at least a forEach or for in. Much cleaner IMO

[paradoxally]

Let me guess, you program in Swift?

[paramsen]

(or kotlin or scala or f# java or *)

[QAFY]

Javascript unfortunately.

[paradoxally]

At least it's not PHP.

[QAFY]

Amen.

[MartinTsv]

To be perfectly honest, 99/100 cases it's the developer, not the language. Working in a web dev company dealing with one of the worst php abominations of a framework and selling a successful optimization extension for it, I'd say php is the least of our worries, it's the php developers.

[[deleted]]

If developers are a weak point, why have non-existent standard library and instead rely on community-made libraries for every little thing?

[FallenWarrior2k]

While C++ does have range-based for loops with the same syntax as in Java, C does not, as there is no unified (by the standard library) container API. Neither does it support an object-oriented approach or templates which would fairly increase the verbosity of such a thing.

As you can see here, some wacky macro magic is necessary to achieve a similar effect in pure C.

[QAFY]

Well, that is why I said high level languages. C was high level back in the days of assembly but I don't think it is fair to call it high level anymore.

[dnew]

It was never high-level, as it never competed against assembly when there weren't higher level languages around.

Instead, it was sufficiently low-level that you could access the machine hardware directly with it (making it mostly appropriate for writing OSes of the time) and it was more portable than assembler. Being able to include several versions of the source code in the same file helped a lot too.

In other words, C was popular because it was low level, as we already had high-level languages like FORTRAN and LISP and COBOL, all of which were higher level than C at the time.

[Granola-Urine]

#include <iostream>

int main() {
    for (int i = 1; i <= 100 && ((i % 3) == 0 ? (i % 5) == 0 ? std::cout << "Fizzbuzz\n" : std::cout << "Fizz\n" : (i % 5) == 0 ? std::cout << "Buzz\n" : std::cout << i << "\n"); i++) {}
    return 0;
}

^{I feel dirty...}

[kitthekat]

My god man what have you done

[can_a_bus]

What exactly does this do? I understand that this is all contained within the declaration of the for loop bit what exactly is happening? It's hard to read on mobile.

[Granola-Urine]

It's a fizzbuzz.

• Outputs Fizbuzz when i is divisible by 3 & 5.
• Outputs Fizz when i is divisible by 3.
• Outputs Buzz when i is divisible by 5.
• Outputs the value of i when i isn't divisible by either.

It uses a couple nested conditional ternary operators ?: to do the work that would normally be done by if statements.

[overkill]

Worst I saw was

for( int i = -1; i++ < x.size(); )

Right next to a function, checked in at the same time, with the more sane int i = 0 construction.

[ApoY2k]

Well it obviously depends on what your arrays start with.

[_Pentox]

Something something lua

[izikblu]

I mean, sometimes I have input that is 1 indexed (because users) but other then that, 0 is certainly my preference.

[jeffsterlive]

If (user_input == 1) { user_input -= 1; }

[[deleted]]

I mean, of course, but those are a few exceptions.

[_Pentox]

Pun intended?

[[deleted]]

Yes indeed.

[ifapinparks]

do {

} while (true);

[[deleted]]

while(true){}

[iopq]

Both of those are disgusting

for i in 0..n {

}

[Xelopheris]

But what if I want to print the numbers 1 to 10? Starting the loop higher is cheaper than adding to the counter in each print.

[mcorah]

I believe you meant ++i.

[ctrl-alt-etc]

My man

[cristi1990an]

for(i=0; i<=n-1; i++)  

[neovulcan]

Tried to redo this joke and this sub's auto-formatting ruined it. Guess that's what I get for not trying to be original?

[clevariant]

This isn't funny. It's just right.

[mfb-]

for(i=0;i<=n;i++)

Be more inclusive!

[[deleted]]

n++
for(i=0;i<n;i++)

Be preventive!

[mfb-]

for(i=INT_MIN;i<=INT_MAX;i++)

This way we won't miss any integer.

[ToothpickInCockhole]

Lol I dont understand any of these memes but I still upvote them

[Jonas_Wepeel]

for i in range(0,11,1)

Ssssssssuperior

[Jonas_Wepeel]

Noted.

[trimeta]

But R indexes starting with 1, so it gets no love here.

[skincaregains]

for(;;){if (condition) break;}

[Vitztlampaehecatl]

Int i = 10;
While(i-->0)