The main reason is that classic C casts make no distinction between what we call static_cast<>(), reinterpret_cast<>(), const_cast<>(), and dynamic_cast<>(). These four things are completely different. A static_cast<>() is usually safe. There is a valid conversion in the language, or an appropriate constructor that makes it possible. The only time it’s a bit risky is … Read more
string s = (string)o; // 1 Throws InvalidCastException if o is not a string. Otherwise, assigns o to s, even if o is null. string s = o as string; // 2 Assigns null to s if o is not a string or if o is null. For this reason, you cannot use it with … Read more
How to convert an array to object in PHP?
In C++ operators (for POD types) always act on objects of the same type. Thus if they are not the same one will be promoted to match the other. The type of the result of the operation is the same as operands (after conversion). if: either is long double other is promoted > long double … Read more
Casting in Java isn’t magic, it’s you telling the compiler that an Object of type A is actually of more specific type B, and thus gaining access to all the methods on B that you wouldn’t have had otherwise. You’re not performing any kind of magic or conversion when performing casting, you’re essentially telling the … Read more
The compiler is right, an array of arrays (or a pointer to an array) is not the same as a pointer to a pointer. Just think about how they would be laid out in memory: A matrix of size MxN in the form of an array of arrays: +————–+————–+—–+—————-+————–+—–+——————+ | matrix[0][0] | matrix[0][1] | … … Read more
The answer below the line was written in 2008. C# 7 introduced pattern matching, which has largely replaced the as operator, as you can now write: if (randomObject is TargetType tt) { // Use tt here } Note that tt is still in scope after this, but not definitely assigned. (It is definitely assigned within … Read more
Straight from the API Specifications for the ClassCastException: Thrown to indicate that the code has attempted to cast an object to a subclass of which it is not an instance. So, for example, when one tries to cast an Integer to a String, String is not an subclass of Integer, so a ClassCastException will be … Read more
How do I check if a string is a number (float)?
double num = 5; That avoids a cast. But you’ll find that the cast conversions are well-defined. You don’t have to guess, just check the JLS. int to double is a widening conversion. From ยง5.1.2: Widening primitive conversions do not lose information about the overall magnitude of a numeric value. […] Conversion of an int … Read more