It’s good practice to keep the mutex close to the data it is destined to protect. If a mutex ought to protect concurrent access to fields of a struct value, it’s very convenient to add the mutex as a field of that struct, so its purpose is obvious. If in your app there is only … Read more
You should never expect them outperform assignments. The reason is, the compiler will use memcpy anyway when it thinks it would be faster (if you use optimize flags). If not and if the structure is reasonable small that it fits into registers, direct register manipulation could be used which wouldn’t require any memory access at … Read more
I would make the choice based on the following criteria reference type vs value type semantics. If 2 objects are only equal if they are the same object, it indicates reference type semantics => class. If the value of its members defines equality (e.g. 2 DateTimes are equal if both represent the same point in … Read more
No, flexible arrays must always be allocated manually. But you may use calloc to initialize the flexible part and a compound literal to initialize the fixed part. I’d wrap that in an allocation inline function like this: typedef struct person { unsigned age; char sex; size_t size; char name[]; } person; inline person* alloc_person(int a, … Read more
std::pair provides pre-written constructors and comparison operators. This also allows them to be stored in containers like std::map without you needing to write, for example, the copy constructor or strict weak ordering via operator < (such as required by std::map). If you don’t write them you can’t make a mistake (remember how strict weak ordering … Read more
Short answer (for the C++ part of the question): The Itanium ABI for C++ prohibits, for historical reasons, using the tail padding of a base subobject of POD type. Note that C++11 does not have such a prohibition. The relevant rule 3.9/2 that allows trivially-copyable types to be copied via their underlying representation explicitly excludes … Read more
Prerequisites For this answer I’m going to assume you know how to use pointers, structs, and have a basic understanding of the C language. Also if you don’t know. When talking about the speed of algorithms and data structures you should know the terms: O() = (it’s pronounced “Big-oh”) Big-oh or O() refers to the … Read more
The pointer returned by localtime (and some other functions) are actually pointers to statically allocated memory. So you do not need to free it, and you should not free it. http://www.cplusplus.com/reference/clibrary/ctime/localtime/ This structure is statically allocated and shared by the functions gmtime and localtime. Each time either one of these functions is called the content … Read more
Firstly, do you really have to have a mutable struct? They’re almost always a bad idea. Likewise public fields. There are some very occasional contexts in which they’re reasonable (usually both parts together, as with ValueTuple) but they’re pretty rare in my experience. Other than that, I’d just create a constructor taking the two bits … Read more
sizeof(SomeStruct) != sizeof(SomeStructSource). This will cause someone to find you and murder you someday.