For a bit of facts here is the relevant text from the specifications Equality operator (==,!=) Pointers to objects of the same type can be compared for equality with the ‘intuitive’ expected results: From ยง 5.10 of the C++11 standard: Pointers of the same type (after pointer conversions) can be compared for equality. Two pointers … Read more
It’s a “pointer to member” – the following code illustrates its use: #include <iostream> using namespace std; class Car { public: int speed; }; int main() { int Car::*pSpeed = &Car::speed; Car c1; c1.speed = 1; // direct access cout << “speed is ” << c1.speed << endl; c1.*pSpeed = 2; // access via pointer … Read more
Using pointers alone you can’t properly pass-by-reference or return-by-reference. Some methods require a reference. How would you implement a copy-constructor? Sometimes you need to enforce aliasing. You can’t do that with pointers – they can be changed. References cannot bind to something different. So when you initialize a reference, you guarantee it will refer to … Read more
Pointers to elements of arrays are allowed to point to a valid element, or one past the end. If you increment a pointer in a way that goes more than one past the end, the behavior is undefined. For your 0-sized array, p is already pointing one past the end, so incrementing it is not … Read more
You are actually attempting the impossible. The very heart of the matter is simple: virtual and template do not mix well. template is about compile-time code generation. You can think of it as some kind of type-aware macros + a few sprinkled tricks for meta programming. virtual is about runtime decision, and this require some … Read more
According to the Go Programming Language Specification: A type implements any interface comprising any subset of its methods and may therefore implement several distinct interfaces. For instance, all types implement the empty interface: interface{} If you search within that document for interface{}, you’ll see quite a few examples of how you can use it to … Read more
No need to cast from or to a pointer to void in C: 6.3.2.3 Pointers 1 A pointer to void may be converted to or from a pointer to any incomplete or object type. A pointer to any incomplete or object type may be converted to a pointer to void and back again; the result … Read more
Is it a good idea to use intptr_t as a general-purpose storage (to hold pointers and integer values) instead of void*? No. intptr_t is not guaranteed to exist. First, as you note, it was introduced in C99. Second, implementations are not required to have an integer type big enough to hold converted pointer values without … Read more
Right, there’s a number of things to consider. First up: let’s start with the obvious syntax error in your pointer example: type Employee struct { FirstName *string `json:”name”` Salary *int `json:”salary”` FullTime *bool `json:”fullTime”` } So I’ve moved the asterisk to the type, and I’ve captialized the fields. The encoding/json package uses reflection to set … Read more
In this case a[4] is the 5th integer in the array a, ap is a pointer to integer, so you are assigning an integer to a pointer and that’s the warning. So ap now holds 45 and when you try to de-reference it (by doing *ap) you are trying to access a memory at address … Read more