@programminginc - страница 1195

Talula

Goto in pretty much any language is bad practice

In original BASIC it was impossible to program without GOTO reason for it were line numbers.

Kat

Except basic lol

Talula

Except basic lol

+1

Stefan

Don't use goto in either C or C++ unless you can justify it or have to.

then you dont have loops

Stefan

actually, why dijkstra said goto is cancerous is because its unfortunate couplance with turing machine

Stefan

and not with algorithm

Stefan

if you really look into automata theory, you will see loops are indeed constructed using jumps/goto

olli

then you dont have loops

are you saying you need goto statements to have loops?

Stefan

are you saying you need goto statements to have loops?

yes

Stefan

try to read assembly back and forth, which is already a form of random access machine and a universal turing machine

Stefan

you will see

olli

try to read assembly back and forth, which is already a form of random access machine and a universal turing machine

That's a jump in most cases.

Stefan

That's a jump in most cases.

jumps are goto

Stefan

dijkstra wanted people to not think about low level constructs

Stefan

but pure high level thing like algorithm and data structure

olli

jumps are goto

Then you probably did not get my initial statement. goto decrease readability and maintainability in C/C++ Code and should be avoided unless you can justify it's usage. Additionally C++ does not define the instructions used on assembly level.

olli

yes

So Java does not support loops 🤷‍♂

Stefan

Then you probably did not get my initial statement. goto decrease readability and maintainability in C/C++ Code and should be avoided unless you can justify it's usage. Additionally C++ does not define the instructions used on assembly level.

if we cant have goto, we lose the ability to create state automata

Stefan

So Java does not support loops 🤷‍♂

the underlying jvm bytecodes are still jmp

Kat

Assembly just uses jmp for loops

Kat

So essentially all loops are gotos. But if the language you are using abstracts those gotos then use that abstraction 100% of the time. It's good practice.

olli

Nobody is questioning this. But a language such as C or C++ does not need goto statements to support loops

Avezy

cmp eax, 1 jz 0x04a876

Stefan

so how do you do state transition without goto

Kat

Nobody is questioning this. But a language such as C or C++ does not need goto statements to support loops

It does behind the scenes

Stefan

abstract each state into one method?

Kat

But it abstracts those into something useful

Avezy

cmp eax, 1 jz 0x04a876

Jz is Basically jmp

Talula

Nobody is questioning this. But a language such as C or C++ does not need goto statements to support loops

Agreed

Kat

Behind the abstraction, all languages are just doing jne, je, jmp, call, etc behind the scenes

olli

Behind the abstraction, all languages are just doing jne, je, jmp, call, etc behind the scenes

That's what the CPU is doing. Can you cite a paragraph where the standard actually defines this?

Kat

No, but that's just how it works.

Kat

A compiler just converts the syntax of a higher level language to machine code.

Kat

Any loop in a higher level language is essentially just conditional jumping

olli

A compiler just converts the syntax of a higher level language to machine code.

And that's why you don't need goto statements in you higher level language

Kat

I think we're a little confused here

Kat

Are you saying that a higher level language doesn't involve gotos or use them in any way or are you saying that you shouldn't use gotos in a higher level language?

Stefan

That's what the CPU is doing. Can you cite a paragraph where the standard actually defines this?

although c++ abstract machine only defines high level structure

olli

Are you saying that a higher level language doesn't involve gotos or use them in any way or are you saying that you shouldn't use gotos in a higher level language?

Again, you should not use goto statements in your c/c++ code unless you can justify it's usage. I am well aware loop, conditions ... are translated to jumps

Kat

Again, you should not use goto statements in your c/c++ code unless you can justify it's usage. I am well aware loop, conditions ... are translated to jumps

Ah okay

Kat

I thought you were disagreeing about jumps being used behind the higher level code for some reason. My bad.

olli

I think we can agree on it, cant we? :)

Kat

Yeah lol

Stefan

http://wezfurlong.org/blog/2004/jul/goto-isnt-evil/

Stefan

also, without goto, you cannot effectively exit an inner loop without a flag

Talula

Without JMP computer wouldn't even work but... in C/C++ you don't need goto, I haven't written a sigle program in my life that needed goto in C/C++/C# (I don't even know if C# has goto).

⚛ Hz

also, without goto, you cannot effectively exit an inner loop without a flag

Use longjmp 😃

Stefan

Use longjmp 😃

olli

also, without goto, you cannot effectively exit an inner loop without a flag

This is (imo) a valid justification. The link basically said the same I did. If you have a valid reason to use it, then use it. Goto should however not be a replacement for your regular loops. (As it might be intended by the poll author)