Apr 13, 2010 · If you ever need the true size of a struct in C++ (to distinguish between a truly empty struct vs one with a char in it), you can defeat sizeof's lie with std::is_empty_v<T> ? 0 : sizeof(T);. –

Sep 9, 2011 · There is no first element, so you get an exception. Without seeing your code (which would be very helpful here), it sounds like you've got an empty array or list, and you're asking for the first element (which doesn't exist). For example: System.out.println(anArray[0]); //prints "Hello". anArray[0] gets the first element.

Feb 11, 2021 · The value zero can certainly be represented by size_t, so that is what it gets initialized to. You may write size_t num = 0U; if you prefer aesthetically to have the signedness match, but its effect is just the same.

Jul 10, 2014 · You would usually want your zero (in fact variable) size array to know its size at run time. Then pack that in a struct and use flexible array members , like e.g.: struct my_st { unsigned len; double flexarray[]; // of size len };

Aug 6, 2013 · While I'd need to look at the standard to be sure, I would have a very high suspicion that yes, you must delete the pointer. It would seem odd to me to have a special exception for when you've allocated an array of size 0.

Mar 17, 2018 · (1) writing a proposal to modify the standard for C++20 and allow size 0 objects. (2) actually implementing this in real optimizing compilers. Thoughts on (1): Presumably the reason that EBO is allowed at all is because C does not have inheritance, so we don't break layout compatibility with C.

Dec 26, 2024 · In order to determine the size of data types on a particular machine, C++ provides an operator named sizeof. The sizeof operator is a unary operator that takes either a type or a variable, and returns the size of an object of that type (in bytes). You can compile and run the following program to find out how large some of your data types are:

Dec 9, 2024 · sizeof returns the size of a type or expression in bytes, represented as a size_t value at compile-time. Does sizeof work for all data types? Yes, sizeof works for primitive types, arrays, structs, classes, pointers, and user-defined types.

Aug 14, 2024 · When applied to a reference type, the result is the size of the referenced type. When applied to a class type, the result is the number of bytes occupied by a complete object of that class, including any additional padding required to place such object in an array.

Nov 16, 2020 · public boolean isEmpty() { return size() == 0; } So you can safely assume that !list.isEmpty() is equivalent to list.size() > 0. As for "what is better code", if you want to check if the list is empty or not, isEmpty() is definitely more expressive.