Re: memcpy

From:

Christopher Pisz <nospam@notanaddress.com>

Newsgroups:

comp.lang.c++

Date:

Wed, 04 Feb 2015 17:41:04 -0600

Message-ID:

<mauald$v0e$1@dont-email.me>

On 2/4/2015 5:25 PM, Mr Flibble wrote:

On 04/02/2015 22:56, Christian Gollwitzer wrote:

Am 04.02.15 um 22:31 schrieb Christopher Pisz:

If you want to use a unsigned int then use an unsigned int. There is no
purpose at all to use a typedefed renaming when you intend on it being
an specific type anyway. If you want to know the size, then use sizeof.

Fixed-width integers are very useful types in many fields of computing.
In fact, I claim that they are more useful then the "polymorphic" int,
long, short nonsense. For example, to implement the Mersenne twister you
need to use unsigned 64 bit arithmetics. Or to read image files from
disk into memory, you need unsigned 8 bit or unsigned 16 bit integer
types. Extremely easy if you have either cstdint or inttypes, but
extremely annoying when you need to remember that long on Windows is
always 32bit regardless of pointer size, whereas it is 64 bit on a 64bit
Linux and 32 bit on a 32bit Linux etc. The names of these typedefs are
also widespread and there is cstdint, added in C++11 for that. I can't
understand why you think these are not useful, and I don't see why you
think it is a C problem rather than a C++ one.

OTOH, using the generic "int" makes the program behave differently on
different platforms. For example a program computing the factorial using
integer arithmetics overflows for different input at different
platforms, if just int or unsigned is used.

Why are you computing factorials when there are well tested, documented,
and widely used libraries already to do this?

Why don't you know what platform you are on?

"int" should REALLY mean an
integer, i.e. something that never overflows. Too late to get that into
the core C++, though.

I couldn't agree with you more. The MISRA safety critical C++ coding
standard even bans the use of 'int', 'char' etc and enforces the use of
the sized integer typedefs to help ensure that there are no nasty
surprises causing planes to fall out of the sky etc.

I can find you a standard that says use GOTO as well, if you like.

Personally when I am not using iterators to loop I use std::size_t to
index (not 'int') and the sized integer typedefs nearly everywhere else.
IMO tt is important to know what the valid range of values for a
scalar type is in any algorithm and the sized integer typedefs allow
this.

No, they don't.
As stated before, the types in stdint.h _are not guaranteed_

and no, it isn't
Who gives a flying poop what how many bits unsigned int count is in:

for(unsigned count = 0; count < 100; ++count)
{
}

as long as 100 fits, and 100 _will always_ fit.

and as stated before, _you already know your architecture_ for your project.

People who do silly things to be "platform independent" when platform
independence is not even necessary are silly.

IMO 'int' should really only be used as the return type for main()!

/Flibble

I hope I never ever have to work on your code.