And it's copying that's costly

nope

this how vectors are implemented

Anyway, I don’t think c is good with dynamic arrays. You should go to c++ as they have an efficient library called std::vector if you really want dynamic arrays.

Okay wait I think I'm missing something I know that array backed lists and vectors are implemented this way, but I had always understood malloc to be extremely cheap (albeit dangerous if done hazaphardly) And that the truly costly part of reallocating arrays was moving stuff over to the new one

Anyway, I don’t think c is good with dynamic arrays. You should go to c++ as they have an efficient library called std::vector if you really want dynamic arrays.

can we use RAII technique in C ? 🤔

Okay wait I think I'm missing something I know that array backed lists and vectors are implemented this way, but I had always understood malloc to be extremely cheap (albeit dangerous if done hazaphardly) And that the truly costly part of reallocating arrays was moving stuff over to the new one

come to ot group

Hi, I'm learning Qt and Qml and how to integrate them with c++ but I'm really confused, could someone give some advice?

Hi, I'm learning Qt and Qml and how to integrate them with c++ but I'm really confused, could someone give some advice?

connect QML with C++ you mean ?

connect QML with C++ you mean ?

yeah and about QML, it's a weird language

yeah and about QML, it's a weird language

https://doc.qt.io/qt-5/qtqml-cppintegration-topic.html

https://doc.qt.io/qt-5/qtqml-cppintegration-topic.html

I've read it but I'm still confused. Thx anyway

yeah and about QML, it's a weird language

qml is similar to java-script, good programming language for UI design. what wired ?

qml is similar to java-script, good programming language for UI design. what wired ?

I see it as a combination of HTML, CSS, JAVASCRIPT and it got a way of defining user-defined types

qml is similar to java-script, good programming language for UI design. what wired ?

and I'm still confused about property binding

What is the binary search working time algorithm?

Is this O(n)

I've read it but I'm still confused. Thx anyway

write a class that inheritance from QObject and then write your functions that you need call from qml then register that on main function, import into qml file, like what said at documents. it's not very wired 🤔 get some example and do like that.

What is the binary search working time algorithm?

O(log n)

and I'm still confused about property binding

https://www.youtube.com/watch?v=e35ugcY2aOk

https://www.youtube.com/watch?v=e35ugcY2aOk

I just need to understand the mechanism of doing that. In other words, how is that allowed to happen, what's happening under the hood?

Polynome *polynome=NULL; polynome->p = malloc(counter*sizeof(Monom)); polynome->len=(unsigned int) counter;

this makes me an segamentation fault

clang doesn't warn me about any potentiel warining or error

I just need to understand the mechanism of doing that. In other words, how is that allowed to happen, what's happening under the hood?

I'm sorry for accurate explanation, but AFAIK all qml components are QObject classes (or inhertanced from that) defined in C++, so you just defining some other one and registering that in qml. (sorry for my English :)

What is a good beginner one-day project for C++ starter? Im searching for ideas

write a chat server and client

I'm sorry for accurate explanation, but AFAIK all qml components are QObject classes (or inhertanced from that) defined in C++, so you just defining some other one and registering that in qml. (sorry for my English :)

so a ".qml" file is a class or "object" in c++?

so a ".qml" file is a class or "object" in c++?

No I don't think so. I meant QML components are C++ classes inheritance from QObject not QML itself or qml files.

No I don't think so. I meant QML components are C++ classes inheritance from QObject not QML itself or qml files.

components like Timer or ...

Polynome *polynome=NULL; polynome->p = malloc(counter*sizeof(Monom)); polynome->len=(unsigned int) counter;

Could you paste the code?

No I don't think so. I meant QML components are C++ classes inheritance from QObject not QML itself or qml files.

yeah I got that, I meant like an item element and all its child elements in qml is a class or object in c++

Polynome *polynome=NULL; polynome->p = malloc(counter*sizeof(Monom)); polynome->len=(unsigned int) counter;

You assigned it to null

Why did you do that?

#include<iostream> #include<string> using namespace std; int main (){ string entered_password; cout<<"Enter your password:\n"; cin>>entered_password; string saved_password = "12gh34jk56"; if (entered_password == saved_password){ cout<<"You are allowed.\n"; } else{ cout<<"You are not allowed.\n"; } string data; cout<<"Enter some data:\n"; getline(cin, data); cout<<"You entered:\n "<<data; return 0; }

The output:

Enter your password: 12gh34jk56 You are allowed. Enter some data: You entered: [Program finished]

yeah I got that, I meant like an item element and all its child elements in qml is a class or object in c++

yes I guess so but I'm not sure. sorry. wait for someone's accurate explanation.

Why does the getline function does not store my text?

Polynome *polynome=NULL; polynome->p = malloc(counter*sizeof(Monom)); polynome->len=(unsigned int) counter;

You tried to access an unitized pointer(which gives you segmentation fault).

yes I guess so but I'm not sure. sorry. wait for someone's accurate explanation.

ok, thank you, I really appreciate it.

Why did you do that?

clang said me to do that

ok, thank you, I really appreciate it.

👍🏻🌹 good luck.

@kyoko687 can we continue in a hour ? I have something to do right now sorry

clang said me to do that

poly2.c:28:2: warning: variable 'polynome' is uninitialized when used here [-Wuninitialized] polynome->p = malloc(counter*sizeof(Monom)); ^~~~~~~~ poly2.c:27:20: note: initialize the variable 'polynome' to silence this warning Polynome *polynome; ^ = NULL

@kyoko687 can we continue in a hour ? I have something to do right now sorry

You need to understand how malloc works. Please refer to the docs: https://www.cplusplus.com/reference/cstdlib/malloc/ Or search in YouTube. I cannot explain complex subject in the chat.

ok thak you for your help !

It's even better when you learn C++ without knowing C

Hmm, I don't agree with you, there are lot of functions from C , lot of new operators that based on C

poly2.c:28:2: warning: variable 'polynome' is uninitialized when used here [-Wuninitialized] polynome->p = malloc(counter*sizeof(Monom)); ^~~~~~~~ poly2.c:27:20: note: initialize the variable 'polynome' to silence this warning Polynome *polynome; ^ = NULL

Clang didn't mean the fix you've done. If you really want "polynome" on heap you need to : Polynome *polynome=(Polynome ) malloc (sizeof(Polynome));

ok thak you for your help !

Also this will help: https://en.m.wikipedia.org/wiki/Pointer_(computer_programming)

Hmm, I don't agree with you, there are lot of functions from C , lot of new operators that based on C

#stop_teaching_c_as_cpp_preamble

Watch this talk

It's even better when you learn C++ without knowing C

Actually no, c++ has so many extra things that makes it pretty confusing(for beginners). If you understand c pretty will, c++ will be a breeze.

Clang didn't mean the fix you've done. If you really want "polynome" on heap you need to : Polynome *polynome=(Polynome ) malloc (sizeof(Polynome));

yes it works !

Actually no, c++ has so many extra things that makes it pretty confusing(for beginners). If you understand c pretty will, c++ will be a breeze.

If you're trolling right now, I'll ban you

thanks all for help

If you're trolling right now, I'll ban you

I’m not my opinion :)

I’m not my opinion :)

And a wrong one

#stop_teaching_c_as_cpp_preamble

Simple example is operator new that contains malloc

Simple example is operator new that contains malloc

No, it doesn't

I’m not my opinion :)

you can't , if it's wrong opinion 🤣

Show me a standard paragraph where it stated that operator new calls malloc

Show me a standard paragraph where it stated that operator new calls malloc

you can find it in book "system programming in Linux" Robert Love

you can find it in book "system programming in Linux" Robert Love

It's not C++ :)

It's not C++ :)

? There have explanation about malloc in a chapter and also mention new

If you say something about C++ it should be correct according to the C++ Standard, not a random book

If you say something about C++ it should be correct according to the C++ Standard, not a random book

Ok if you know then explain me how does it work ?

Ok if you know then explain me how does it work ?

Why would I? It's part of implemention

You don't understand how CPU works but you still use it

Does anyone know what compiler supports c++20, and whether Cmake supports it or not? I've done some research but I didn't get a clear answer. I'm starting a new project and I need to know if I can use modules, contracts, etc.

you can find it in book "system programming in Linux" Robert Love

It's compiler designer assignment how implement new and delete, It hasn't a standard definition.

Does anyone know what compiler supports c++20, and whether Cmake supports it or not? I've done some research but I didn't get a clear answer. I'm starting a new project and I need to know if I can use modules, contracts, etc.

There's no contracts in C++20

You don't understand how CPU works but you still use it

I get it

It's compiler designer assignment how implement new and delete, It hasn't a standard definition.

It's better to say: It has a definition (what it should do) but doesn't have a standard implementation

There's no contracts in C++20

what about the rest? can I use them

Does anyone know what compiler supports c++20, and whether Cmake supports it or not? I've done some research but I didn't get a clear answer. I'm starting a new project and I need to know if I can use modules, contracts, etc.

You don’t need to migrate, wait for a bit.

Does anyone know what compiler supports c++20, and whether Cmake supports it or not? I've done some research but I didn't get a clear answer. I'm starting a new project and I need to know if I can use modules, contracts, etc.

https://en.cppreference.com/w/cpp/compiler_support > C++20 core language features

what about the rest? can I use them

You can do whatever you want! https://en.cppreference.com/w/cpp/compiler_support

CMake doesn't support modules afaik

CMake doesn't support modules afaik

what build system does?

what build system does?

I don't know

You can do whatever you want! https://en.cppreference.com/w/cpp/compiler_support

Ther is partial support for some features like modules. can I still use them without any problems?