Need a C++ guru

Shendare · #1 06-30-2009, 07:24 PM

According to the assembly generated, my Visual C++ 2008 appears to treat both as unsigned ints.

Different compilers may implement such things in their own way, however.

**KLS** · #2 06-30-2009, 07:32 PM

Depends, MSC++ 32 bit compiler treats long and int essentially the same, however you can't rely on this being the case on other platforms or software configurations.

Kobaz · #3 06-30-2009, 07:50 PM

So in the following code snippet:

Code:

int a = -1;

unsigned int b = 3000000000; // 3 billion

if ( a > b) { "true" >> cout } else { "false" >> cout };

what comes out in Visual C++?

Shendare · #4 06-30-2009, 08:03 PM

My compiler outputs "true" in the presented situation.

Microsoft Visual C++ 2008 Standard on WinXP Pro 32-bit.

Kobaz · #5 06-30-2009, 08:19 PM

What about:

Code:

int a = -1;

unsigned int b = 3000000000; // 3 billion

if ( long(a) > long(b)) { "true" >> cout } else { "false" >> cout };

?

Shendare · #6 06-30-2009, 08:32 PM

Still true. In 32-bit, long is the same as int, so they're both being cast as signed ints at that point, changing b from 3000000000 to -1294967296, which is less than -1.

Kobaz · #7 06-30-2009, 09:04 PM

Sigh. To an old Smalltalk programmer like me, I have to wonder why C++ is called "Object Oriented". I try to understand the language, but it seems to be quite unintuitive.

I'm struggling to understand the emu code - I keep expecting fundamental data types to "do the right thing, with no surprises". How do people write robust correct code in C++ without going mad?

Thanks for your time, I'll just keep away from the code, as I seem to break things due to my Smalltalkness. Perhaps I'm just too old..... everything got hard after about 1986. And don't get me started on Java....