A recent blog post by a self-described Rust programmer examines several technical characteristics of the C programming language that often surprise developers transitioning from Rust or other modern languages. The article, published on Hacker News, outlines specific implementation details and historical design choices in C that differ from Rust's approach.

The author begins by noting that learning C after Rust is uncommon, as most programmers encounter C or C++ first. They observe that while numerous tutorials exist for "Rust for C Programmers," the reverse perspective is rare. The post clarifies it does not aim to replace formal C education but rather compiles observations made during self-directed study.

One section details C's boolean implementation history. The language originally used integers 0 and 1 to represent truth values. The C99 standard introduced a dedicated boolean type via the stdbool.h header, defining true and false as macros expanding to 1 and 0. Although C23 now treats _Bool as a native primitive type, earlier versions require explicit inclusion of the header. The author notes this evolution reflects C's incremental standardization process.

Another segment compares string handling models. In Rust, string references carry explicit length metadata, occupying 16 bytes (8 for address, 8 for length). C instead uses null-terminated strings, where each string ends with a \0 byte. This design eliminates the need for a separate length variable but requires allocating extra space for the terminator and risks buffer overflows if omitted. The author provides a string reversal example in C that explicitly manages the null terminator, contrasting it with Rust's more straightforward implementation that avoids manual memory management concerns.

The article also addresses portability challenges with integer types. It presents a table showing how C's basic integer types (char, short, int, long, long long) have platform-dependent sizes. Specifically, long is 64 bits on Unix-like systems but only 32 bits on Windows. To address this inconsistency, the author recommends using fixed-width types from stdint.h (e.g., int32_t, uint64_t) for cross-platform code, noting that Rust's type system enforces explicit size choices through types like u32 and isize.

Error handling practices in C draw particular criticism. Unlike Rust's Result type, which forces explicit error handling through compile-time checks, C functions often return integer codes or null pointers to signal failure. The author highlights that functions like malloc() can fail silently, potentially causing crashes if null pointers are dereferenced without checks. They describe an attempted C implementation of Rust-like error handling using tagged unions, concluding that such workarounds remain cumbersome and lack compiler enforcement of error handling.

Field access syntax differences are noted between C and Rust. C uses . for direct struct access and -> for pointer access, whereas Rust consistently uses . regardless of indirection level. The author references a Stack Overflow discussion about the historical origin of the -> operator in early C compilers.

Array behavior is another focus. The post explains that arrays decay into pointers when passed to functions, causing sizeof() to return pointer size rather than array size. This often leads to bugs, as demonstrated in an example where array parameters appear to consume 8 bytes instead of their actual 3-byte length. The author mentions that Clang warns about this common pitfall.

The absence of references and borrow checking in C is discussed in the context of pointer arithmetic. While Rust enforces memory safety through its ownership system, C allows direct memory manipulation via raw pointers, enabling operations like iterating through arrays using pointer arithmetic. The author cautions that such practices risk buffer overflows and security vulnerabilities if not handled carefully.

The article concludes by summarizing the author's mixed experience with C. They express appreciation for learning the language's underlying mechanics but state they are unlikely to use C for personal projects. All code examples referenced in the post are available on GitHub, and the author indicates openness to future exploration of C++.

The blog post was published on October 7, 2026, according to its metadata. It appears in the technology section of Hacker News, a site known for aggregating developments in software engineering and computer science.