I believe this is currently underspecified in the standard, like many issues such as What is the value category of the operands of C++ operators when unspecified?. I don’t think it was intentional, like hvd points outs it is probably obvious to the committee. In this specific case I think we have the evidence to … Read more
The keyword int aliases System.Int32 which still requires 4 bytes, even on a 64-bit machine.
It still behaves as an operator. Cast is also operator and also evaluates it’s argument and so does * or & . Being an operator is a syntactic category. That does not change. The important distinction is that it behaves as expression while in other cases it behaves as constant. Update: I commented below that … Read more
In C ‘a’ is an integer constant (!?!), so 4 is correct for your architecture. It is implicitly converted to char for the assignment. sizeof(char) is always 1 by definition. The standard doesn’t say what units 1 is, but it is often bytes.
Why does this work? This works because sizeof is a compile time construct, with the exception of variable length arrays is not evaluated at all. If we look at the C99 draft standard section 6.5.3.4 The sizeof operator paragraph 2 says(emphasis mine): […] The size is determined from the type of the operand. The result … Read more
You want vector::size() and set::size(). Assuming v is your vector, do this: size_t size = 0; for (vector<set<char> >::const_iterator cit = v.begin(); cit != v.end(); ++cit) { size += cit->size(); } sizeof() is giving you the in-memory size of the object/type it is applied to, in multiples of sizeof(char) (usually one byte). If you want … Read more
firstname is a char array carrying a trailing 0-terminator. lastname is a pointer. On a 64bit system pointers are 8 byte wide.
From C99 spec, section 6.2.5, paragraph 27: A pointer to void shall have the same representation and alignment requirements as a pointer to a character type. Similarly, pointers to qualified or unqualified versions of compatible types shall have the same representation and alignment requirements. All pointers to structure types shall have the same representation and … Read more
All the compiler knows about is the pointer, which is why you’re getting the size of the pointer back. To see the size of the allocated object, use one of the following code snippets: With ARC: #import <malloc/malloc.h> // … NSLog(@”Size of %@: %zd”, NSStringFromClass([myObject class]), malloc_size((__bridge const void *) myObject)); Without ARC: #import <malloc/malloc.h> … Read more
If you have an array then sizeof(array) returns the number of bytes the array occupies. Since each element can take more than 1 byte of space, you have to divide the result with the size of one element (sizeof(array[0])). This gives you number of elements in the array. Example: std::uint32_t array[10]; auto sizeOfInt = sizeof(std::uint32_t); … Read more