If you have two overloaded functions:
double maximum(double a, double b, double c);
int maximum(int a, int b, int c);
They work fine if you call maximum() with all arguments as doubles, or
all as ints. But, if you mix up doubles with ints in the argument
list, it doesn't know which maximum() to call... but only one could
possibly match -- the one that takes doubles.
I assume this is not a bug, and is by definition... but, why?
Jason
15  2039 
Jason Doucette wrote:
If you have two overloaded functions:
double maximum(double a, double b, double c);
int maximum(int a, int b, int c);
They work fine if you call maximum() with all arguments as doubles, or
all as ints. But, if you mix up doubles with ints in the argument
list, it doesn't know which maximum() to call... but only one could
possibly match -- the one that takes doubles.
I assume this is not a bug, and is by definition... but, why?
Floating-integral conversions (from a double to an int) and floating
point conversions (from an int to a double) have the same rank as far
as overload resolution is concerned.
V
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Floating-integral conversions (from a double to an int) and floating
point conversions (from an int to a double) have the same rank as far
as overload resolution is concerned.
Ok. I didn't think that implicit conversions from a double to an int
were *ever* allowed, since they can lose information.
Jason
Jason Doucette wrote:
>Floating-integral conversions (from a double to an int) and floating
point conversions (from an int to a double) have the same rank as far
as overload resolution is concerned.
Ok. I didn't think that implicit conversions from a double to an int
were *ever* allowed, since they can lose information.
If something potentially dangerous would always be disallowed, we'd not
have many feature of the language. Just imagine dereferencing a pointer
not allowed because (Oh, no!) the pointer can be invalid!
V
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Jason Doucette wrote:
>Floating-integral conversions (from a double to an int) and floating
point conversions (from an int to a double) have the same rank as far
as overload resolution is concerned.
Ok. I didn't think that implicit conversions from a double to an int
were *ever* allowed, since they can lose information.
It's worse than that. The conversion from double to int discards the
fractional part, but if the resulting integer is outside the bounds of int,
it's undefined behaviour.
--
rbh
Robert Bauck Hamar wrote:
Jason Doucette wrote:
>>Floating-integral conversions (from a double to an int) and floating
point conversions (from an int to a double) have the same rank as
far as overload resolution is concerned.
Ok. I didn't think that implicit conversions from a double to an int
were *ever* allowed, since they can lose information.
It's worse than that. The conversion from double to int discards the
fractional part, but if the resulting integer is outside the bounds
of int, it's undefined behaviour.
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask
Robert Bauck Hamar wrote:
Jason Doucette wrote:
>>Floating-integral conversions (from a double to an int) and floating
point conversions (from an int to a double) have the same rank as
far as overload resolution is concerned.
Ok. I didn't think that implicit conversions from a double to an int
were *ever* allowed, since they can lose information.
It's worse than that. The conversion from double to int discards the
fractional part, but if the resulting integer is outside the bounds
of int, it's undefined behaviour.
I am not sure in what sense it's a loss of information, actually. The
conversion is well-defined, it discards the fractional part and retains
the integral part, in the same fashion as when you divide two integers
the result is [essentially] rounded to the next integer toward zero.
Is that a loss of information? <shrug>
V
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On Jul 27, 12:04 am, Jason Doucette <jdouce...@gmai l.comwrote:
Floating-integral conversions (from a double to an int) and floating
point conversions (from an int to a double) have the same rank as far
as overload resolution is concerned.
Ok. I didn't think that implicit conversions from a double to an int
were *ever* allowed, since they can lose information.
It's a serious bug in the standard. There have been several
proposals to "deprecate" such implicit conversions (one by
Stroustrup himself, I think), but for whatever reasons, they
never got anywhere.
--
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Ok. I didn't think that implicit conversions from a double to an int
were *ever* allowed, since they can lose information.
If something potentially dangerous would always be disallowed, we'd not
have many feature of the language. Just imagine dereferencing a pointer
not allowed because (Oh, no!) the pointer can be invalid!
Your example is on a totally different level.
Everyone knows almost every floating point value converted to an
integer results in a significant loss of information. Most languages
disallow this implicit casting from floating point to integer. I
would assume C / C++ did this also. In fact, it does -- you cannot
assign a floating point value to an integer.
So, it's intuitive to think that this would not be considered within
the overload resolution... I am still dumbfounded as to why it does.
Jason
It's worse than that. The conversion from double to int discards the
fractional part, but if the resulting integer is outside the bounds of int,
it's undefined behaviour.
Are you positive about that? I thought it set it to the maximum /
minimum integer value... In my programs, if there's a case a floating
point will be out of integer range, I check before the cast, just in
case. I don't think I've ever tested what would happen if I didn't...
Jason This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics | |
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