Answer from the C FAQ: The Prime 50 series used segment 07777, offset 0 for the null pointer, at least for PL/I. Later models used segment 0, offset 0 for null pointers in C, necessitating new instructions such as TCNP (Test C Null Pointer), evidently as a sop to all the extant poorly-written C code … Read more
Yes it’s inherited from C. The function: void foo ( char a[100] ); Will have the parameter adjusted to be a pointer, and so becomes: void foo ( char * a ); If you want that the array type is preserved, you should pass in a reference to the array: void foo ( char (&a)[100] … Read more
If you have your array in scope you can use sizeof to determine its size in bytes and use the division to calculate the number of elements: #define NUM_OF_ELEMS 10 int arr[NUM_OF_ELEMS]; size_t NumberOfElements = sizeof(arr)/sizeof(arr[0]); If you receive an array as a function argument or allocate an array in heap you can not determine … Read more
This is a C++ interview test question not homework. Then your interviewer needs to refresh his recollection with how the C++ standard works. And I quote: For an enumeration whose underlying type is not fixed, the underlying type is an integral type that can represent all the enumerator values defined in the enumeration. The whole … Read more
sizeof is a compile time operator.
Before C was standardized, many compilers would have had no difficulty handling zero-size types as long as code never tried to subtract one pointer to a zero-size type from another. Such types were useful, and supporting them was easier and cheaper than forbidding them. Other compilers decided to forbid such types, however, and some static-assertion … Read more
Function Pointers can have very different sizes, from 4 to 20 bytes on an x86 machine, depending on the compiler. So the answer is no – sizes can vary. Another example: take an 8051 program. It has three memory ranges and thus has three different pointer sizes, from 8 bit, 16 bit, 24 bit, depending … Read more
The type void has no size; that would be a compilation error. For the same reason you can’t do something like: void n; EDIT. To my surprise, doing sizeof(void) actually does compile in GNU C: $ echo ‘int main() { printf(“%d”, sizeof(void)); }’ | gcc -xc -w – && ./a.out 1 However, in C++ it … Read more
Size of a pointer should be 8 byte on any 64-bit C/C++ compiler, but not necessarily size of int.
I was mucking around looking for similar functionality when I stumbled on this: Is it possible to print out the size of a C++ class at compile-time? Which gave me the idea for this: char (*__kaboom)[sizeof( YourTypeHere )] = 1; Which results in the following warning in VS2015: warning C4047: ‘initializing’: ‘DWORD (*)[88]’ differs in … Read more