Hey guys, it is written on "A Tour of C++" that this book is for those who have coded before. Can complete beginners also learn C++ programming language from it?

You don't know that, it's undefined behavior

Technically yes, which is why I said that you shouldn't assume in the message below (but you clearly decide to skip reading that one), but you could get weird results for operations which include a read and a store (for example an increment) for an operation which is just a store you can't get a different result

Technically yes, which is why I said that you shouldn't assume in the message below (but you clearly decide to skip reading that one), but you could get weird results for operations which include a read and a store (for example an increment) for an operation which is just a store you can't get a different result

Ah sorry I must have missed that. As for the rest, yeah, that's why it's formally UB

2. "Two expression evaluations conflict if one of them modifies a memory location ([intro.memory]) and the other one reads or modifies the same memory location." 21. [...] Two actions are potentially concurrent if - they are performed by different threads, [...] The execution of a program contains a data race if it contains two potentially concurrent conflicting actions, at least one of which is not atomic, and neither happens before the other [...]. Any such data race results in undefined behavior. http://eel.is/c++draft/intro.races#2 http://eel.is/c++draft/intro.races#21

how do i type in the or operator?

how do i type in the or operator?

logical-or || bitwise-or |

what symbols are these on the keyboard

the pipe character?

what symbols are these on the keyboard

might depend on your locale. On intl keyboards they look like this |

might depend on your locale. On intl keyboards they look like this |

ok i got them thank you

/report

What

What

exactly

that moron just added me into his group

how puny

Whew

Why we just not prevent the error of "out of the index bound" by using the % arithmetic operator Like if we have an array of size 10 And the user asked for the 15th element We just write arr[15%10]

Better than throwing the processor to read a non-related data, right?!

Anyway Eventually you'll have to go the long way Cuz a good program causes exceptions in this type of operations(with the need of if statement)

Why we just not prevent the error of "out of the index bound" by using the % arithmetic operator Like if we have an array of size 10 And the user asked for the 15th element We just write arr[15%10]

a comparison is faster

a comparison is faster

If (15>10)??!!

division is a long operation

If (15>10)??!!

yes

only if it is, you do the modulo

but why would you want to do that?

Its still additional work

Better than throwing the processor to read a non-related data, right?!

why?

think before posting

But the comparison will make you worry about another things like What to do in case of errors But here you'll definitely provide the user the request

But the comparison will make you worry about another things like What to do in case of errors But here you'll definitely provide the user the request

again: why would you need that?

Rust does it - and it doesnt really help too much

again: why would you need that?

What?!!

It's sooo obviouse Why would I need to provide the results?!!

It's sooo obviouse Why would I need to provide the results?!!

what?

what?

That's what you asked

Why you'd need that?

Need what?!

I mean - if you do the modulo thing, you end up with data that doesnt help you

if you do the exception you might as well cause a sigsev

I mean - if you do the modulo thing, you end up with data that doesnt help you

What?!!!

read what I said

The right results are data that don't help me?!!

The right results are data that don't help me?!!

you want to do the modulo thing in order to avoid sigsevs, right?

you want to do the modulo thing in order to avoid sigsevs, right?

Yeah

Well if I have an out-of-bounds, the data that I get by modulo will be unrelated

And worry about the headache

in a sorting algorithm, it would cause data to be duplicated

which would be even more fatal since you never find out

+ again: division is slow

Well if I have an out-of-bounds, the data that I get by modulo will be unrelated

That will never happen

Why we just not prevent the error of "out of the index bound" by using the % arithmetic operator Like if we have an array of size 10 And the user asked for the 15th element We just write arr[15%10]

exists others technical for prevent Array/pointers bound

103737636%10 Is certainly under 10

103737636%10 Is certainly under 10

read again what I said

in a sorting algorithm, it would cause data to be duplicated

^

exists others technical for prevent Array/pointers bound

Exceptions yeah

again: you don't need such things

in a sorting algorithm, it would cause data to be duplicated

How?! Like?!

any check is slower than none

How?! Like?!

imagine that instead of getting an out of bounds exception, I just get the data from the start again

a comparison is faster

is not always true..

is not always true..

subtraction is slower than division?

🤨

Exceptions yeah

http://www.doc.ic.ac.uk/~phjk/BoundsChecking.html

subtraction is slower than division?

depending on your value a division is/can be a shift (for divisors 2^n) hence not always

imagine that instead of getting an out of bounds exception, I just get the data from the start again

Hmmm Maybe that would be a headache But we can in some cases use the module operator

depending on your value a division is/can be a shift (for divisors 2^n) hence not always

we are talking about the modulo part of the division 😉

+ that only works with div by 2^n

depending on your value a division is/can be a shift (for divisors 2^n) hence not always

shift only for Power of two

shift only for Power of two

true

http://www.doc.ic.ac.uk/~phjk/BoundsChecking.html

Okay I'll check it

there is no generalization.. do the benchmarks

we are talking about the modulo part of the division 😉

how do you get a modulo by shifting? @ollirz @Drazzy ?

how do you get a modulo by shifting? @ollirz @Drazzy ?

You mean the reminder?!

You mean the reminder?!

yes, thats a modulo

yes, thats a modulo

Oh

there is no generalization.. do the benchmarks

^

how do you get a modulo by shifting? @ollirz @Drazzy ?

look at the output of compilers when modulo 2^n

^

No, divisions are slower because they are done by loop