#malloc in c

[fortunatelycoldengineer]

What is the difference between malloc() and calloc()? . . . . for more interview questions https://bit.ly/3EteTnZ check the above link

[rocket-penguin]

Internet Coder™: We're going to learn some low-level embedded techniques!

Internet Coder™: -heap allocates-

Internet Coder™: -uses OS call-

Internet Coder™: -uses stdlib string function-

Internet Coder™: -generally not careful with memory usage-

Internet Coder™: And that's how you write embedded code!

[removeload-academy]

C Malloc() Function in Hindi | What is Malloc() Function | Dynamic Memory Allocation By Malloc()

The malloc() function in C is used to allocate a block of memory on the heap. It is defined in the stdlib.h header file and returns a pointer to the first byte of the allocated memory block. For more details, so Kindly check my website URL.https://www.removeload.com/c-malloc-function

[brandizzi]

🚀 Melhoramos nossa implementação de malloc(), agora garantindo alinhamento de memória para evitar desperdício e melhorar a performance. Pequenos ajustes, grandes impactos! Quer entender como isso funciona e por que faz diferença? Confira no post 👇

[electricmeatorchestra]

Terrence Malick’s next movie should be a tone poem about the beauty and terror of dynamically allocating heap memory so that I can get to the punchline Terrence malloc

[0x4468c7a6a728]

i know it says it says it's a random number but still

0100 0100 0110

1000 1100 0111

1010 0110 1010

0111 0010 1000

it's kinda pretty ya know? binary poetry but little silly and cute . whimsical even (/gen /not flirting)

the secret is that it's technically not random i just say that to get fewer asks about it lol, it's a pointer from a random run of a C program that mallocs 8 bytes

[roadrunnerposting]

was working on a pretty cool c++ class today which was basically a high-performance allocator that takes a whole pool of memory from the OS at initialisation and allocates it in a linear way without the possibility of freeing the memory, except for when the allocations are reset. it literally just increments a pointer across the block when you call malloc and resets the pointer when you reset the allocator

[01001110011001010111001001100100]

Learn C, so you don't know the difference between functions and wizard names. Quiz under the cut:

1: Malloc.

2: Acos.

3: Emeric.

4: Fileof.

5: Alastair

6: Radagast

7: Fread

8: Hypot

9: Isascii

10: Arcturus

11: Perror

12: Orion

---Answer---

1: C func

2: C func

3: Wizard

4: C func

5: Wizard

6: Wizard

7: C func

8: C func

9: C func

10: Wizard

11: C func

12: Wizard

[jedi--archives]

javaはおじいちゃん、cはひいじいちゃんって感じ

私： なんか、javaってCよりはめんどくさくないというか、メモリの確保とか開放までやんないといけないcよりはまだ親切っていうような感じなのね

でも最近のモダンな開発言語よりは当然手厚く介護してあげないといけないおじいちゃんみたいな

Cはひいじいちゃんみたいな

ChatGPT: その感覚、よく分かります！Javaは確かにCと比べると、メモリ管理などの面倒な部分を自動でやってくれる分、開発者にとってはかなり親切です。Cでは手動でメモリの確保 (malloc など) や開放 (free など) をする必要があり、これが原因でメモリリークやクラッシュの原因になることもあります。それに比べて、Javaではガベージコレクタがメモリの開放を自動で行ってくれるため、プログラマが直接気を使うことは少なくなっています。

ただ、最近のモダンなプログラミング言語（Python, JavaScript, Rust, Go など）と比べると、Javaはまだ「手厚く介護」してあげる必要がある部分がありますね。例えば、型の宣言や細かいエラーハンドリング、場合によってはマニュアルでメモリ効率を最適化するような場面もあります。これが言わば「おじいちゃん」的な部分です。

Cはもっと古くて、システムの根幹を扱うための言語であり、メモリやハードウェアに対する直接的なコントロールが求められるので、「ひいじいちゃん」って感じがしますね。Cは非常にパワフルだけど、その分自分で全て面倒を見なければならない。Javaはその次の世代で、ある程度の「介護」が用意されたけれど、まだモダン言語ほど手軽ではないという印象ですね。

それでも、Javaは信頼性や移植性の高さ、長い歴史での成熟度から、いろいろな場面で使われ続けている「ベテラン」な言語です！

[hob28]

Advanced C Programming: Mastering the Language

Introduction

Advanced C programming is essential for developers looking to deepen their understanding of the language and tackle complex programming challenges. While the basics of C provide a solid foundation, mastering advanced concepts can significantly enhance your ability to write efficient, high-performance code.

1. Overview of Advanced C Programming

Advanced C programming builds on the fundamentals, introducing concepts that enhance efficiency, performance, and code organization. This stage of learning empowers programmers to write more sophisticated applications and prepares them for roles that demand a high level of proficiency in C.

2. Pointers and Memory Management

Mastering pointers and dynamic memory management is crucial for advanced C programming, as they allow for efficient use of resources. Pointers enable direct access to memory locations, which is essential for tasks such as dynamic array allocation and manipulating data structures. Understanding how to allocate, reallocate, and free memory using functions like malloc, calloc, realloc, and free can help avoid memory leaks and ensure optimal resource management.

3. Data Structures in C

Understanding advanced data structures, such as linked lists, trees, and hash tables, is key to optimizing algorithms and managing data effectively. These structures allow developers to store and manipulate data in ways that improve performance and scalability. For example, linked lists provide flexibility in data storage, while binary trees enable efficient searching and sorting operations.

4. File Handling Techniques

Advanced file handling techniques enable developers to manipulate data efficiently, allowing for the creation of robust applications that interact with the file system. Mastering functions like fopen, fread, fwrite, and fclose helps you read from and write to files, handle binary data, and manage different file modes. Understanding error handling during file operations is also critical for building resilient applications.

5. Multithreading and Concurrency

Implementing multithreading and managing concurrency are essential skills for developing high-performance applications in C. Utilizing libraries such as POSIX threads (pthreads) allows you to create and manage multiple threads within a single process. This capability can significantly enhance the performance of I/O-bound or CPU-bound applications by enabling parallel processing.

6. Advanced C Standard Library Functions

Leveraging advanced functions from the C Standard Library can simplify complex tasks and improve code efficiency. Functions for string manipulation, mathematical computations, and memory management are just a few examples. Familiarizing yourself with these functions not only saves time but also helps you write cleaner, more efficient code.

7. Debugging and Optimization Techniques

Effective debugging and optimization techniques are critical for refining code and enhancing performance in advanced C programming. Tools like GDB (GNU Debugger) help track down bugs and analyze program behavior. Additionally, understanding compiler optimizations and using profiling tools can identify bottlenecks in your code, leading to improved performance.

8. Best Practices in Advanced C Programming

Following best practices in coding and project organization helps maintain readability and manageability of complex C programs. This includes using consistent naming conventions, modularizing code through functions and header files, and documenting your code thoroughly. Such practices not only make your code easier to understand but also facilitate collaboration with other developers.

9. Conclusion

By exploring advanced C programming concepts, developers can elevate their skills and create more efficient, powerful, and scalable applications. Mastering these topics not only enhances your technical capabilities but also opens doors to advanced roles in software development, systems programming, and beyond. Embrace the challenge of advanced C programming, and take your coding skills to new heights!

[fortunatelycoldengineer]

What is the difference between near, far and huge pointers? . . . . for more interview questions https://bit.ly/3EteTnZ check the above link

[mentalisttraceur-software]

When I was younger and still stuck thinking in terms of concrete current implementations more than abstract semantics and their best possible implementations, I kept wanting to bypass the standard library, especially in low-level languages like C, because the standard library had code paths I didn't need.

If I knew I didn't need my newly allocated memory to start zeroed out, I disliked calling calloc, because a naive implementation of calloc implies extra work, and most implementations would imply extra work at least some of the time. Because I failed to conceive of the OS and hardware having extremely efficient code and circuitry for giving us zeroed out memory pages, and I failed to conceive of optimizing compilers generating code which doesn't bother zeroing out that memory if you truly never read those bytes before writing them.

If I just wanted one memory allocation for the lifetime of the program, I disliked calling malloc at all, because most malloc implementations have a complex memory allocator which is only more optimal for larger and churnier memory usage. I wanted to call the rawest, most direct memory allocation operation - for example, on modern Linux that's an mmap system call asking for an anonymous page (or for a mapping of /dev/zero, although I later learned of sloppy/overbroad SELinux policies in production, f.e. on some Android devices, which reject opening or mapping /dev/zero). Or I wanted to just manually try to grow the stack (and have raw feedback from the kernel if I didn't have enough). Because I was stuck thinking about what the concrete implementations I had on hand would do. Instead, I should've been imagining the optimizing compiler which can look at a simple "malloc", and at everything else in the code, and at any optimization preferences and other information passed in when invoking the compiler, and just compile that malloc as a raw memory system call, or as a stack allocation, if that's actually the best thing to do in that situation.

Painstakingly chipping away at this has been one of the most liberating and healing things for me as a software developer. This is why I eventually realized that we should "code for the optimizer" rather than optimizing by hand in almost every situation. But it took the overwhelming accumulation of examples of actual real-world situations where automatic optimizations beat manual fiddling, or did just as well, and where the manual fiddling was actively counter-productive.

I wish they taught this in schools or something. Just one class, one semester, which is mostly just a showcase of "here's some code. here's how it could be inefficient. how might we optimize this? yeah, yeah, cool, cool... good ideas class. Now here's what a modern compiler can do if you just give it the simple code that doesn't try to optimize. Notice how it did everything you thought of, plus things you didn't. And oh look, if we change the optimization tuning from execution speed to memory usage for example, the compiler can optimize the simple code totally differently, but our hand-optimized code is stuck using more memory, because the compiler can no longer discern the relevant intent and invariants in this code - and neither could a human, without extensive comments and context".

I know lots of developers just don't care, but it would go a long way towards either unblocking or constructively directing the type of developer who can be very productive but would otherwise spend too much time prematurely or needlessly optimizing in the wrong places.

[stumpyjoepete]

Ok, this is a niche thing to complain about, but it insane to me that the situation with strict aliasing rules in C and C++ has such a monumental mismatch between the standard and what people actually want and need to do:

For a long time, there was no standard-compliant way to alias a piece of memory using two different types.[1] I mean, people did it anyway, but whether you got fucked over by the optimizer was dependent on how you did it, which things were in which translation unit (or I suppose whether someone did LTO), which compiler you used, which compiler-specific attributes or flags you used, and/or luck.

memcpy has (always?) been blessed as a way to bit-cast between types, but, as the name implies, it copies data--there's no way to just ask for a single memory location with two different views onto it, although the compiler may or may not be smart enough to avoid actually copying stuff.

It was only in C11--published in 2011!--, that the popular method of union-based type-punning was finally added to explicitly clarified to be in the standard. This is often good enough for what you want to do, but it's not enough--you can't write a standard-compliant implementation of malloc in C11 (or C17), as far as I can tell![2]

The union trick is not kosher in C++, but they added bit_cast (which is basically type-safe memcpy) in C++20, and they're adding start_lifetime_as in C++23, which I think actually makes it possible to write a standard-compliant malloc? Or do the type-punning you wanted to do to fucking begin with?

There aren't that many super great reasons to start a new project today in C or C++. But if you're writing an operating system or a language runtime or doing embedded programming or whatever, there weren't really any good alternatives for a long time. But these are exactly the situations where you want to alias the same memory via different types! I feel like I am taking crazy pills!

tl;dr -- regular C programmers talking with the people who write the language standard and the optimizers in compilers:

[1]: Someone is going to bring up the thing about char*. You are allowed to alias anything as a char*. This is sufficient if all you want to do is print out the underlying representation or twiddle the bits one at a time, but it's only one way! You can't start with a char* and then alias it as something else. This doesn't get you what you want with type-punning, and it's definitely not enough to make malloc work.

[2]: Yes, really. I think you could make some very trivial malloc implementations (no-op free or just delegating every malloc/free to a system call and never recycling memory) in a standard-compliant way, but otherwise no. I don't see anything C23 that's relevant to the situation. It ironically might be possible to write a standard-compliant malloc in C++ using the new C++23 features though, and I think someone is trying to do this in llvm's in-progress libc.

[removeload-academy]

C Malloc() Function in Hindi | What is Malloc() Function | Dynamic Memory Allocation By Malloc()

The malloc() function in C is used to allocate a block of memory on the heap. It is defined in the stdlib.h header file and returns a pointer to the first byte of the allocated memory block. For more details, so Kindly check my website URL. https://www.removeload.com/c-malloc-function

[brandizzi]

Implementando malloc() e free() — dividindo blocos grandes

When implementing malloc(), it is important to consider the size of the allocated blocks. For example, reusing blocks too big for smaller requests cause memory waste. How to solve that? Let's see on this post of our series on malloc() and free().

No artigo anterior da série, vimos como a ordem em que escolhemos que blocos de memória reutilizar pode levar a maior ou menor consumo de memória, e mudamos nossas funções para evitar esse desperdício. Mas precisamos resolver outro problema, até mais grave: às vezes, um bloco de memória muito grande pode ocupar o espaço que vários blocos menores poderiam usar. Considere o caso abaixo, em que…

[commieclimbercatboy]

If you need a quick little script: learn python.

If you wanna understand how your computer works: learn C.

Bit more nuance below the cut

People often say to start with Python or another high level language, but I think that starting with C is actually really useful. C has a relatively direct translation to machine code, meaning that if you can competently read C code (which you learn by writing C) you will understand what your computer is actually doing under the hood, which can help you even if you're writing in a higher level language later. And yes, it's a bit more complicated, but it's so valuable, and going from a low level language to a high level one is so much easier than the other way around.

The reason I recommend C over Rust, which is also a low level language and has the big advantage of being memory safe, is that with Rust's memory safety comes an abstraction layer that means it doesn't help you understand how your PC works. Your computer allocates and frees memory, regardless of what language you write your program in; if you're coding as a learning exercise rather than making a safety critical product, it's better to use malloc() and free() IMO.

please learn how to code

like, if you're bored today, and not doing anything,

learn a little bit of coding please