@programminginc - страница 1848

Anonymous

&arr is a pointer to array which type is T (*)[n]

Anonymous

it's not. since arr is a pointer (hence size 8 or 4...)

It is not

olli

which snippet are we talking about?

Anonymous

Sorry, if I'm wrong

Anonymous

T arr[n] is array arr is array that decays to a pointer

I'm talking about this one

Anonymous

I'm talking about this one

I was asking about the code I mentioned.

Anonymous

int* fun(int *arr, int len){ int *b = new int[5]; //inserting values into array b return b; } int main(){ //made an array arr and the int *b = fun(arr,len); //How to iterate through array b } If I want to iterate through array b, then how do i know the length of b in main?

This one

olli

U can try :)

#include <cstdio> void printArraySize(int * arr) { int size = sizeof(arr)/sizeof(arr[0]); printf("Size: %d\n", size); } int main() { int array[100]; printArraySize(array); } Output: 2

Anonymous

This one

There's no arr

olli

There's no arr

parameter to the funciton

Anonymous

parameter to the funciton

Ok, it's definitely a pointer

Anonymous

#include <cstdio> void printArraySize(int * arr) { int size = sizeof(arr)/sizeof(arr[0]); printf("Size: %d\n", size); } int main() { int array[100]; printArraySize(array); } Output: 2

is that 2?

olli

is that 2?

On most system yes. It comes down to sizeof(void*) / sizeof(int)

Anonymous

I would use a std::array or a reference to array instead

Anonymous

I would use a std::array or a reference to array instead

can you give code snippet of 2nd one?

Anonymous

can you give code snippet of 2nd one?

It's c++ only

Anonymous

It's c++ only

I didn't get "reference to array" meaning

Anonymous

template <std::size_t n> void my_func(int (&arr)[n])

Anonymous

It's a reference to array

Anonymous

With an arbitrary size n

Anonymous

okk. I've seen this but hated understanding it.

olli

And the size needs to be a known at compile time

Anonymous

And the size needs to be a known at compile time

Definitely It is "static" C-array

Anonymous

int n; cin>>n; int b = n-5; So, we call the value of b to be known at run-time. Right?

olli

int n; cin>>n; int b = n-5; So, we call the value of b to be known at run-time. Right?

yes The 5 would be compile time

Anonymous

There are many other things in cpp that look like (arr)[n]. "Something like this". Can anyone put the link or what do we call the above thing?

Anonymous

I want to check this stuff.

Anonymous

There are many other things in cpp that look like (arr)[n]. "Something like this". Can anyone put the link or what do we call the above thing?

Cppreference.com

Anonymous

Cppreference.com

what do we call this?

Anonymous

I mean what to search for?

Anonymous

Idk Got this with experience

klimi

nite

olli

There are many other things in cpp that look like (arr)[n]. "Something like this". Can anyone put the link or what do we call the above thing?

well in this case the parentheses have no effect. Often its related to pointer to functions or array references.

Anonymous

well in this case the parentheses have no effect. Often its related to pointer to functions or array references.

Or pointer to arrays😂

{CSA}

Hey

Anonymous

Hey

Wow there's C++ itself

{CSA}

Yeah

Francesco

Wow there's C++ itself

Ahahah

Emma Nexus

Hi

Emma Nexus

Sup

Emma Nexus

Im new here

Dima

Emma Nexus

Hahaha

Dima

Why

Mat

Stop bothering people

Anonymous

I am beginner to c plz tell me where to start..

C.

I am beginner to c plz tell me where to start..

#googleit

Anonymous

Start

Pete

Why do I sometimes get random negative integers in a series of numbers?

Pete

I understand there must be some error but I’d like to know why it’s doing that first

Liam

I understand there must be some error but I’d like to know why it’s doing that first

show your MWE.

Pete

fib sequence without using recursion

Liam

int overflow

Liam

search it.

Pete

towards about the 50th number itll start going negative

Pete

I will

dont

I am beginner to c plz tell me where to start..

Use book Sumita Arora

Pete

should I store the number after a certain point? Is there a wy to avoid it

dont

The problem is with data type

dont

Use biggest data type

Liam

should I store the number after a certain point? Is there a wy to avoid it

Basically, the root of the problem is that you are trying to store a too-large integer into a int32_t variable.

dont

It won't be negative

Liam

try int64_t or uint64_t.

Liam

Or, you'll have to utilize std::string to implement a bigint class and related operators to store and manipulate arbitrarily large integers.

Pete

try int64_t or uint64_t.

I appreciate it 👍

Anonymous

how to write an rar format dexompressor by c/c++?

Anonymous

wget https://www.rarlab.com/rar/rarlinux-x64-5.5.0.tar.gz

Anonymous

how to write an rar format dexompressor by c/c++?

There are libs for this stuff Just google it

Marián

guys any ideas why is ifstream so slow?

Anonymous

guys any ideas why is ifstream so slow?

Well.. because it's I/O It's always slow

Marián

nope, my ifstream is extremfly slow maybe because i am reading the file by lines in while loop

Marián

i am trying to load 200000+ lines file

Anonymous

nope, my ifstream is extremfly slow maybe because i am reading the file by lines in while loop

Again I/O is always slow

Marián

in c# i read all lines at once and that managed it in program memory

Marián

Again I/O is always slow

not this way, in c# i could load that file in matter of 2-3 seconds, here its about minute

Anonymous

i am trying to load 200000+ lines file

Especially with this much of data

Anonymous

how are you reading it?

Artöm

There are many other things in cpp that look like (arr)[n]. "Something like this". Can anyone put the link or what do we call the above thing?

You mean (smth)[whatever] ? This is either operator[] call or dereferencing with offset

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Studio.h function?