This article describes the differences well: A key difference between casting and the as operator is the behavior on failure. When a cast fails in ActionScript 2, null is returned. When a cast fails in ActionScript 3, a TypeError is thrown. With the as operator in ActionScript 3, whenever a cast fails the default value … Read more
I hat the same problems with a library of mine providing “plugin”-functionality… I got it finally working… Here was my problem: I had one main assembly using plugins, one assembly with the plugin (Plugin.dll) AND (important) another assembly providing the plugin-functionality (Library.dll). The Plugin.dll referenced the main assembly (in order to be able to extend … Read more
Function style casts bring consistency to primitive and user defined types. This is very useful when defining templates. For example, take this very silly example: template<typename T, typename U> T silly_cast(U const &u) { return T(u); } My silly_cast function will work for primitive types, because it’s a function-style cast. It will also work for … Read more
For types for which such cast is permitted (e.g. if T1 is a POD-type and T2 is unsigned char), the approach with static_cast is well-defined by the Standard. On the other hand, reinterpret_cast is entirely implementation-defined – the only guarantee that you get for it is that you can cast a pointer type to any … Read more
For me (using Java 1.6.0_26), the first snippet gives the same exception as the second one. The reason is that the Arrays.asList(..) method does only return a List, not necessarily an ArrayList. Because you don’t really know what kind (or implementation of) of List that method returns, your cast to ArrayList<String> is not safe. The … Read more
First of all, you assume that sizeof(long) == sizeof(int) == sizeof(float). This is not always true, and totally unspecified (platform dependent). Actually, this is true on my Windows using clang-cl and wrong on my Linux using the same 64-bit machine. Different compilers on the same OS/machine can give different results. A static assert is at … Read more
According to the ISO C standard, when you convert an integer to a signed type, and the value is outside the range of the target type, the result is implementation-defined. (Or an implementation-defined signal can be raised, but I don’t know of any compilers that do this.) In practice, the most common behavior is that … Read more
Yes, this is correct behaviour. The reason is that you can have a null pointer, but not a null reference – any reference has to be bound to an object. So when dynamic_cast for a pointer type fails it returns a null pointer and the caller can check for that, but when it fails for … Read more
When thinking about pointers, it helps to draw diagrams. A pointer is an arrow that points to an address in memory, with a label indicating the type of the value. The address indicates where to look and the type indicates what to take. Casting the pointer changes the label on the arrow but not where … Read more
Yes and No. It depends on which version of C++, you’re using. C++98 and C++03 do not support explicit type conversion operators But C++11 does. Example, struct A { //implicit conversion to int operator int() { return 100; } //explicit conversion to std::string explicit operator std::string() { return “explicit”; } }; int main() { A … Read more