According to the change log of C23, proposal n2464 was voted-in and implemented, making realloc(ptr, 0) explicitly undefined behavior, whereas it was supposedly implementation-defined in previous s...

I am looking at the C23 draft standard, but I think this would apply in C11 as well. There are several guarantees about sequence points in relation to function calls in C, such as before the return...

Can I declare a C pointer with an intialization to its own address? void* p = &p; I am specifically concerned with if this is strictly standard compliant in C23 (as the draft currently stands)....

The new standard C (ISO/IEC 9899:2023, aka C23), in the Annex H, several macros and types are defined, relative to real and complex arithmetic, subject to the standard ISO/IEC 60559 (floating-point...

Latest gcc 13.x (trunk) gives a compiler error (gcc -std=c23) for this code: int* p = false; error: incompatible types when initializing type 'int *' using type '_Bool' How can this be correct? ...

C23 introduced new semantics in function declarators: 6.7.6.3 Function declarators [...] 13   For a function declarator without a parameter type list: the effect is as if it were declared with a p...

While answering a question here, I made the following example: #include <stdio.h> #include <math.h> int main (void) { float_t a = -248.75; printf("%f\n", a); unsigned ch...

In the following code, copyThing() is written so that its return value has the same type as its argument value: extern void *copyThingImpl(const void *x); #define copyThing(x) ((typeof(x)) copyThi...

Consider this union: typedef union { void* vptr; nullptr_t nptr; } pun_intended; nullptr_t is supposedly compatible with void* 1). Ok so what if we initialize the void* to some non-zero value? p...

In C23, the nullptr keyword got standardized. I would prefer to use nullptr instead of NULL prior to C23 too because it means that I could write code which compiles in: C, prior to C23 C, since C2...

The wording of the C23 working draft on unsequenced functions is unclear to me. Among other properties, unsequenced functions have to be independent: (6) An object X is observed by a function call...

C23 introduced the attributes [[reproducible]] and [[unsequenced]]. What is the motivation behind them? How are they defined, and what effect do they have on a function? What kind of functions sho...

C++11 added the constexpr keyword which can be added to functions to specify constant behavior. C23 added what seems to be identical functionality in the form of the [[reproducible]] tag. How are t...

C23 introduced a number of floating point types, including but not limited to: _Float32 _Float32x _Float32_t I am unsure of the differences, such as: Are they keywords, or are they type aliases,...

The C23 standard apparently has introduced using "auto" keyword for auto type deduction, see here, just like in C++11. However, there seems to be some differences. According to here, http...

My program: int main(){} In upcoming C23, non-prototype and "K&R style" functions are removed. I realize that C23 is not yet formally released, but the current behavior of gcc and cl...

I'm currently reading the new draft of the C23 standard (N3088), and I've noticed that in §5.2.4.1 the standard states: The implementation shall be able to translate and execute a program that use...

A new preprocessor directive is available in the upcoming C23 Standard: #embed Here is a simple example: // Placing a small image resource. #include <stddef.h> void show_icon(const unsigned...