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Consider:
int* ptr = (int*)0xDEADBEEF;
cout << (void*)&*ptr;
How illegal is the *, given that it's used in conjunction with an immediate & and given that there are no overloaded op&/op* in play?
(This has particular ramifications for addressing a past-the-end array element &myArray[n], an expression which is explicitly equivalent to &*(myArray+n). This Q&A addresses the wider case but I don't feel that it ever really satisfied the above question.)
760
Dereferencing a pointer means getting the value that is stored in the memory location pointed by the pointer. The operator * is used to do this, and is called the dereferencing operator.
Dereferencing is used to access or manipulate data contained in memory location pointed to by a pointer. *(asterisk) is used with pointer variable when dereferencing the pointer variable, it refers to variable being pointed, so this is called dereferencing of pointers.
Response:In Hi-Tech compiler if any pointer variable is modified during code execution, the compiler will give a warning "Dereferencing uninitialized pointer" if the pointer variable is not initialised with some address.To overcome this warning , initialize the pointer variable with any address during the pointer ...
An invalid pointer reference occurs when a pointer's value is referenced even though the pointer doesn't point to a valid block. One way to create this error is to say p=q;, when q is uninitialized. The pointer p will then become uninitialized as well, and any reference to *p is an invalid pointer reference.
According to the specification, the effect of dereferencing an invalid pointer itself produces undefined behaviour. It doesn't matter what you do after dereferencing it.
102
Assuming the variable `ptr' does not contain a pointer to a valid object, the undefined behavior occurs if the program necessitates the lvalue-to-rvalue conversion of the expression `*ptr', as specified in [conv.lval] (ISO/IEC 14882:2011, page 82, 4.1 [#1]).
During the evaluation of `&*ptr' the program does not necessitate the lvalue-to-rvalue conversion of the subexpression `*ptr', according to [expr.unary.op] (ISO/IEC 14882:2011, page 109, 5.3.1 [#3])
Hence, it is legal.
33
It is legal. Why wouldn't it be? You're just setting a value to a pointer, and then accessing to it. However, assigning the value by hand must be obviously specified as undefined behavior, but that's the most a general specification can say. Then, you use it in some embedded software controller, and it will give you the correct memory-mapped value for some device...
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