@programminginc - страница 2614

Ohh, that's exactly my task to implement analog of vector without STL. :D Do I do it correctly, allocating memory with malloc, resizing it with realloc and destructing with free?

Артём

As I understood, it's wrong way to use new when constructing object, because later I'll have to realloc'ate it?

Vlad

As I understood, it's wrong way to use new when constructing object, because later I'll have to realloc'ate it?

Vector implementation shall not use realloc

Anonymous

But you're constrained to x86 then?

No It supported in different architectures You can checkout CMakeLists in oneTBB-2021 branch what platforms it support X86, ARM, mips for sure

Vlad

Vector implementation shall not use realloc

What you do instead is allocate memory by sizeof(T) * power_of_two and then call placement new.

Артём

What you do instead is allocate memory by sizeof(T) * power_of_two and then call placement new.

Why not realloc? It does exactly the same, furthermore it may just expand or contract the existing area, without allocating a new memory block and copying memory area.

Vlad

Why not realloc? It does exactly the same, furthermore it may just expand or contract the existing area, without allocating a new memory block and copying memory area.

Actually in your case you may use it since you don't support std::allocator

Vlad

But it's not the way it's done in STL for that reason

Vlad

Actually in your case you may use it since you don't support std::allocator

Just remember to call placement new on push_back

Артём

Just remember to call placement new on push_back

I'm sorry I don't understand what you mean under 'placement new'?

Vlad

I'm sorry I don't understand what you mean under 'placement new'?

template<typename T> T* alloc() { static constexpr size_t size = (1 << 20); // 1 megabyte static std::byte storage[size]; static size_t offset = 0; T* ptr = new (storage + offset) T; offset += alignof(T); return ptr; } That's a very crude example of usage but I hope you'll get it

Konstantin

I'm sorry I don't understand what you mean under 'placement new'?

I hope I can share URL here. This should help https://en.cppreference.com/w/cpp/language/new

Selmon boi

Can someone share basics of c++

Kenny

Can someone share basics of c++

Google bro?

Konstantin

Can someone share basics of c++

That's pretty much sums it up: “C makes it easy to shoot yourself in the foot; C++ makes it harder, but when you do it blows your whole leg off.” ― Bjarne Stroustrup P.S. read the rules, please.

olli

/warn no need to repost

Артём

template<typename T> T* alloc() { static constexpr size_t size = (1 << 20); // 1 megabyte static std::byte storage[size]; static size_t offset = 0; T* ptr = new (storage + offset) T; offset += alignof(T); return ptr; } That's a very crude example of usage but I hope you'll get it

Ok, thanks for introduction placement new for me. But I still have questions: how to correctly reallocate memory for my vector? placement new here just initializes storage elements on pre-allocated memory.

Артём

So how does memory reallocation work under the hood, if it's not realloc? when used size gets more than reserved and pre-allocated area.

Sammie

/warn

Sammie

OK ma

Sammie

It was a mistake

Twenty19TEight

#include <iostream> using namespace std; class test1{ public: void setname(string x){ name = x; } string getname(){ return name; } private: string name; } int main(){ test1 t1; t1.setname("Mark"); //how do I get this input from user cout<<t1.getname(); return 0; }

Twenty19TEight

please answer

Konstantin

#include <iostream> using namespace std; class test1{ public: void setname(string x){ name = x; } string getname(){ return name; } private: string name; } int main(){ test1 t1; t1.setname("Mark"); //how do I get this input from user cout<<t1.getname(); return 0; }

/report request to solve the assignment

Twenty19TEight

Men this is my own thing Its not an assignment

Twenty19TEight

Idk how to take that input from user so I asked here

Twenty19TEight

I hope u understand

Konstantin