Why do Java and C# not have implicit conversions to boolean?

Question

Since I started Java it's been very aggravating for me that it doesn't support implicit conversions from numeric types to booleans, so you can't do things like:

if (flags & 0x80) { ... } 

instead you have to go through this lunacy:

if ((flags & 0x80) != 0) { ... } 

It's the same with null and objects. Every other C-like language I know including JavaScript allows it, so I thought Java was just moronic, but I've just discovered that C# is the same (at least for numbers, don't know about null/objects): http://msdn.microsoft.com/en-us/library/c8f5xwh7(VS.71).aspx

Microsoft changed it on purpose from C++, so why? Clearly I'm missing something. Why change (what I thought was) the most natural thing in the world to make it longer to type? What on Earth is wrong with it?

Answer 1

For clarity. It makes the following mistake simply illegal:

int x = ...;  if (x = 0)  // in C: assign 0 to x and always evaluate to false     ....     // never executed 

Note: most modern C / C++ compilers will give a Warning (but not an Error) on this straightforward pattern, but there are many variations possible. It can creep up on you.