hi I want to start learning c++, Does anyone have a roadmap?

start with a tutorial or youtube videos then start a simple project you like to work on C and C++ tutorial usually cover computer memory and some basic understanding of it learning C first isn’t necesary, even though I’m good with C I still suffer a lot with C++ standard library and object oriented programming the two languages are similar in syntax but wildly different in standard library which is the thing that provide the basic functions you will use by default in your code like (printf() or cout <<)

For instance I'm not able to differentiate btw struct nd class??

You can imagine that class is a more extended version of struct with the protection of data and has methods to work with its own data.

For instance I'm not able to differentiate btw struct nd class??

a class can have functions while a struct can’t have functions by default. a class can restrict the access of some elements with(protected or private) also with classes the style of programming will be different (called object oriented programming btw) also you are provided with constructors which are something that let you run a function once an object (something like class variable) is created

For instance I'm not able to differentiate btw struct nd class??

Read the pinned message. In that you will find a Resources link which is a channel filled with FAQ. This particular question that you asked has an answer there. https://t.me/cpp20programming/194

For instance I'm not able to differentiate btw struct nd class??

a piece of advise if code with classes try to keep your code as simple as possible and avoid overcomplicating stuffs

a class can have functions while a struct can’t have functions by default. a class can restrict the access of some elements with(protected or private) also with classes the style of programming will be different (called object oriented programming btw) also you are provided with constructors which are something that let you run a function once an object (something like class variable) is created

This is completely wrong. A struct can have methods as well. A struct can use access specifiers. A struct can have constructors and destructors and a struct can be used in OOP.

You can imagine that class is a more extended version of struct with the protection of data and has methods to work with its own data.

Hm okk, thx

a class can have functions while a struct can’t have functions by default. a class can restrict the access of some elements with(protected or private) also with classes the style of programming will be different (called object oriented programming btw) also you are provided with constructors which are something that let you run a function once an object (something like class variable) is created

Oh nice, i understood .. that's helpful :)

This is completely wrong. A struct can have methods as well. A struct can use access specifiers. A struct can have constructors and destructors and a struct can be used in OOP.

a pointer to function is not a function

This is completely wrong. A struct can have methods as well. A struct can use access specifiers. A struct can have constructors and destructors and a struct can be used in OOP.

Really?

a piece of advise if code with classes try to keep your code as simple as possible and avoid overcomplicating stuffs

Hm I'll make sure of that, which compiler do u use?

a pointer to function is not a function

A struct can have methods in it. When did I mention pointers to functions? struct A{ void fun(){} }; This is valid C++ code.

A struct can have methods in it. When did I mention pointers to functions? struct A{ void fun(){} }; This is valid C++ code.

ok my bad, you’re right I was confused with C structures

Structs can also have constructors and destructors.

ok my bad, you’re right I was confused with C structures

In future, if you are not sure about something, please search for it on Google. I already posted a link to the FAQ that deals with differences between a struct and a class. Maybe you can read it too

Can anyone help me why empty class have the return value 1

???

Can anyone help me why empty class have the return value 1

??? What do you mean by a return value of a class?

I mean to say why is the size of empty class is 1

Why it's not zero??

In future, if you are not sure about something, please search for it on Google. I already posted a link to the FAQ that deals with differences between a struct and a class. Maybe you can read it too

since what version that’s valid C++ code? I remmeber that it use to throw errors if I did that

I mean to say why is the size of empty class is 1

To ensure that an array of objects of this empty class get assigned at adjacent bytes so that they can be individually addressed. This would not be possible if the size were zero. For ex: class A{}; void fun(){ A obj[2]; assert(&obj[1] != &obj[0]); } The assertion will not fire because these 2 objects would occupy adjacent bytes. It would not be possible if the size were 0. And the reason why this is important is because the standard requires an array of objects to be contiguously allocated and to be individually addressed. However there is an optimization called Empty Base Class Optimization (EBCO) where compilers will usually not allocate space for the base class sub object in a derived class object if the base class were empty (i.e. it has no data members and virtual functions). In this optimization, the base class subobject effectively has size 0.

since what version that’s valid C++ code? I remmeber that it use to throw errors if I did that

Since C++98 i.e. 25 years back. Actually 1998 is the first time that ISO standardized C++. The previous standard ANSI C++ also supported structs with methods. That is how Bjarne implemented C++.

Since C++98 i.e. 25 years back. Actually 1998 is the first time that ISO standardized C++. The previous standard ANSI C++ also supported structs with methods. That is how Bjarne implemented C++.

nevermind I was using an old version of turbo C++ back then

In future, if you are not sure about something, please search for it on Google. I already posted a link to the FAQ that deals with differences between a struct and a class. Maybe you can read it too

ok thanks

Is Codeblock good for beginners for C ?

Is Codeblock good for beginners for C ?

Good open book K&R about C and install Visual Studio

Good open book K&R about C and install Visual Studio

Okay brother thanks

Guys am new to c++ and am using code blocks So now the problem is that I can't compile my code, its shows no error but I don't know why I can't get my outputs

Guys am new to c++ and am using code blocks So now the problem is that I can't compile my code, its shows no error but I don't know why I can't get my outputs

and it worked before and it just stopped working right?

Yes

did you create some new project or it is just one same project and just by having some delay while compiling it is happening?

No, Its a new project

and you were able to run it before? this project

Yes

and you haven't changed anything?

Yes, but am not sure if I've not temperd with anything, cause I've been going through the settings ever since

and if you create new project it doesnt work too?

Yes

and you don't even see "compiled" or something like that?

It shows something like "process terminated with status......" all in red

Guys am new to c++ and am using code blocks So now the problem is that I can't compile my code, its shows no error but I don't know why I can't get my outputs

Don't do all the project stuff Just create a cpp file and open it with codeblocks

Don't do all the project stuff Just create a cpp file and open it with codeblocks

Oh okay, how

Oh okay, how

Same way you create a text file, right click and all that

OK thanks

If you have extensions hidden, change windows settings then create text document and rename extension to cpp

I'll try that

Kkk

It shows something like "process terminated with status......" all in red

And is there some message with it?

And is there some message with it?

No

Hm, kinda not enough context to determine what is causing problems

Hm, kinda not enough context to determine what is causing problems

No problem Thanks😊

Please am kinda a bigginer in c++ so can someone please help me

Please am kinda a bigginer in c++ so can someone please help me

You haven't said your question

I just need an explanation on how to use it....cuz am actually a python programer just thought c++ may come In handy

I just need an explanation on how to use it....cuz am actually a python programer just thought c++ may come In handy

That's not a question, what explanation do you need? To use what?

Ro print stuff input....use strings,floats and every thing a bigginer needs to know

Ro print stuff input....use strings,floats and every thing a bigginer needs to know

Everything a beginner can simply search on google then

If I want to print a=2.06 then we are using printf("%.2f",a); Exactly if I want to do through C++ Then How can I do by using cout? Thanks in advance 🤙

How can I find it on Google? I mean by what searching?

If I want to print a=2.06 then we are using printf("%.2f",a); Exactly if I want to do through C++ Then How can I do by using cout? Thanks in advance 🤙

https://en.cppreference.com/w/cpp/io/manip/setprecision

How can I find it on Google? I mean by what searching?

"std set precision" worked for me

kzxsbwvinlfh please decide this

Hi guys, is there a reason why strcmp does not return 0? So I have two strings, and a printf before strcmp shows that they are the same (given the two buffers, printf prints the same string, like "hello"). The problem is that, when doing strcmp, it does not find them to be equal. Any suggestions?

lol

Hi guys, is there a reason why strcmp does not return 0? So I have two strings, and a printf before strcmp shows that they are the same (given the two buffers, printf prints the same string, like "hello"). The problem is that, when doing strcmp, it does not find them to be equal. Any suggestions?

Probably what you see through the monitor using printf does not imply a return value of 0. But I'd suggest you provide a minimal reproducible example for your problem first.

yes, here it is: printf("Questo è buff: %s e questa è string_vector[%d]: %s.\n", buff, j, string_vector[j]); fflush(stdout); int ret= strcmp(buff, string_vector[j]); printf("QUesto è ret: %d.\n", ret); fflush(stdout); if(strcmp(buff, string_vector[j]) == 0){ The ret value is 10, for some reason

yes, here it is: printf("Questo è buff: %s e questa è string_vector[%d]: %s.\n", buff, j, string_vector[j]); fflush(stdout); int ret= strcmp(buff, string_vector[j]); printf("QUesto è ret: %d.\n", ret); fflush(stdout); if(strcmp(buff, string_vector[j]) == 0){ The ret value is 10, for some reason

What's the output of stdout then? And what's the type of buff and string_vector[j]?

so buff is char buff[4096] defined in the function; i use it in order to get input from stdin via fgets; string_vector is a global array char **string_vector; I did the malloc of string_vector in the main function as follows: string_vector= malloc(sizeof(*string_vector)*n_process)); And the output is: 1) If "hello" is in buff (what the users gave to the software) and "hello" is in string_vector then printf prints "hello" and "hello"; 2) Ret for some reason is 10; 3) The if clause is never verified

Which platform were you using when you got this result? In particular, the standard library you were using.

Windows 10, but I'm using WSL to compile and run the code I don't know about stdlib, I did include though stdlib, stdio. I guess the stdlib is glibc as the professor named it quite a few times... I tried the software again. The problem is that the condition of "two strings are equal" seems to be 10. No metter the input string, it always returns 10 if they are equal, < 10 if the first one is minor, > 10 if the second one is greater

ok I think I found the problem, that seems to be a '\n' fgets leaves at the end of the first buff when taking the input

for(auto b = RY::Bullets.begin(); b!=RY::Bullets.end(); b++){ SDL_Rect fireballQuadO = r; fireballQuadO.x = b->position.x; fireballQuadO.y = b->position.y; fireballQuadO.w*=0.2; fireballQuadO.h*=0.2; SDL_RenderCopyEx(renderer,fireball,&r,&fireballQuadO,b->angle,NULL,SDL_FLIP_NONE); if(b->update(deltaTime*1000)){ RY::SDL::DrawFrame(explosionTexture, b->finalAnimation.frame,b->position,3); b->finalAnimation.animate(); if(b->finalAnimation.isFinished()){ RY::Bullets.erase(b); // <- error } } }

vector erase gives compiles error

In file included from C:/gcc/lib/gcc/x86_64-w64-mingw32/10.3.0/include/c++/bits/specfun.h:45, from C:/gcc/lib/gcc/x86_64-w64-mingw32/10.3.0/include/c++/cmath:1927, from C:/gcc/lib/gcc/x86_64-w64-mingw32/10.3.0/include/c++/math.h:36, from RYMath:3, from test.cpp:4: C:/gcc/lib/gcc/x86_64-w64-mingw32/10.3.0/include/c++/bits/stl_algobase.h: In instantiation of 'static constexpr _OI std::__copy_move<true, false, std::random_access_iterator_tag>::__copy_m(_II, _II, _OI) [with _II = RY::Bullet*; _OI = RY::Bullet*]': C:/gcc/lib/gcc/x86_64-w64-mingw32/10.3.0/include/c++/bits/stl_algobase.h:469:12: required from 'constexpr _OI std::__copy_move_a2(_II, _II, _OI) [with bool _IsMove = true; _II = RY::Bullet*; _OI = RY::Bullet*]' C:/gcc/lib/gcc/x86_64-w64-mingw32/10.3.0/include/c++/bits/stl_algobase.h:506:42: required from 'constexpr _OI std::__copy_move_a1(_II, _II, _OI) [with bool _IsMove = true; _II = RY::Bullet*; _OI = RY::Bullet*]' C:/gcc/lib/gcc/x86_64-w64-mingw32/10.3.0/include/c++/bits/stl_algobase.h:514:31: required from 'constexpr _OI std::__copy_move_a(_II, _II, _OI) [with bool _IsMove = true; _II = __gnu_cxx::__normal_iterator<RY::Bullet*, std::vector<RY::Bullet> >; _OI = __gnu_cxx::__normal_iterator<RY::Bullet*, std::vector<RY::Bullet> >]' C:/gcc/lib/gcc/x86_64-w64-mingw32/10.3.0/include/c++/bits/stl_algobase.h:601:38: required from 'constexpr _OI std::move(_II, _II, _OI) [with _II = __gnu_cxx::__normal_iterator<RY::Bullet*, std::vector<RY::Bullet> >; _OI = __gnu_cxx::__normal_iterator<RY::Bullet*, std::vector<RY::Bullet> >]' C:/gcc/lib/gcc/x86_64-w64-mingw32/10.3.0/include/c++/bits/vector.tcc:175:2: required from 'std::vector<_Tp, _Alloc>::iterator std::vector<_Tp, _Alloc>::_M_erase(std::vector<_Tp, _Alloc>::iterator) [with _Tp = RY::Bullet; _Alloc = std::allocator<RY::Bullet>; std::vector<_Tp, _Alloc>::iterator = std::vector<RY::Bullet>::iterator]' C:/gcc/lib/gcc/x86_64-w64-mingw32/10.3.0/include/c++/bits/stl_vector.h:1431:24: required from 'std::vector<_Tp, _Alloc>::iterator std::vector<_Tp, _Alloc>::erase(std::vector<_Tp, _Alloc>::const_iterator) [with _Tp = RY::Bullet; _Alloc = std::allocator<RY::Bullet>; std::vector<_Tp, _Alloc>::iterator = std::vector<RY::Bullet>::iterator; std::vector<_Tp, _Alloc>::const_iterator = std::vector<RY::Bullet>::const_iterator]' test.cpp:123:40: required from here C:/gcc/lib/gcc/x86_64-w64-mingw32/10.3.0/include/c++/bits/stl_algobase.h:400:18: error: use of deleted function 'RY::Bullet& RY::Bullet::operator=(RY::Bullet&&)' 400 | *__result = std::move(*__first); | ~~~~~~~~^~~~~~~~~~~~~~~~~~~

#include <bits/stdc++.h> using namespace std; int main() { long long int n,k; vector<int>v; cin >> n >> k; for(int i=1;i<=n;i++) { if(i%2!=0) { v.push_back(i); } } for(int i=1;i<=n;i++) { if(i%2==0) { v.push_back(i); } } //for(int i=0;i<v.size();i++) { cout << v[k-1]<<"\n"; //} return 0; }

how can i avoid time limit exceed on large number?

for(auto b = RY::Bullets.begin(); b!=RY::Bullets.end(); b++){ SDL_Rect fireballQuadO = r; fireballQuadO.x = b->position.x; fireballQuadO.y = b->position.y; fireballQuadO.w*=0.2; fireballQuadO.h*=0.2; SDL_RenderCopyEx(renderer,fireball,&r,&fireballQuadO,b->angle,NULL,SDL_FLIP_NONE); if(b->update(deltaTime*1000)){ RY::SDL::DrawFrame(explosionTexture, b->finalAnimation.frame,b->position,3); b->finalAnimation.animate(); if(b->finalAnimation.isFinished()){ RY::Bullets.erase(b); // <- error } } }

Have you marked the move assignment operator for Ry::Bullet as deleted?

well, I don't think so

here is the class