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unsigned char buf[100] . . . unsigned int val; . . . val = *((unsigned int *)(&buf[1])); . . .
comments?
been there, done that, and, even worse
That comes as no surprise.
When I complained about it to one compiler maker, I was informed "there is nothing in ANSI C about this". I never checked,
Neither does that.
what good does it do to state "there is something in ANSI C about this", if your program does not work because of such.
Well, you see, the standard defines the 'C' language. If you write code that makes assumptions that are not guaranteed by the standard then you cannot reasonably expect your program to work.
I know this will fall on deaf ears, but I'll say it again anyway: if you want to become proficient with a tool you really do need to read and understand the manual.
Mr smoked sardine,
the references to ANSI C had absolutely nothing to do with the point
Let me try to translate my statement to something a smoked sardine can understand: "it makes no sense to discontinue development because of a bug (perceived or real makes no difference) in the tools if there is a workaround"
Word alignment is NOT a C issue but an architecture issue.
Erik
It is nice that you see that I have a lot of experience.
If, on the other hand, you were trying to belittle me, you must have missed "BTW the 'error' was not mine, it occurred ... in my post.
Er5ik
The references to ANSI C had absolutely everything to do with my point, however.
No, that isn't a translation of what you said. It may be what you wish you had said, but it certainly doesn't reflect what you did say.
Word alignment is NOT a C issue
So, why did you complain to the compiler vendor about your problem?
Sadly you do seem to have a lot of experience of bugs which you should never have introduced into the code in the first place. Your assumption when something doesn't work as you expect is that the problem lies with the tools - this is quite typical of those who (as you admit openly, in fact you seem proud of it) haven't read the appropriate documentation.
Note that in this case the 'tool' is the 'C' language, and the 'appropriate documentation' is the definition of the language.
you must have missed "BTW the 'error' was not mine, it occurred ... in my post.
Yes, I noticed you try to salvage some credibility in a followup post.
Of course, were I to 'verify' my assumption that a char is 8 bits every time I type char, I would never get anywhere.
In reality, you have to. But you don't have to do it exactly when you write the 'char' keyword. But you - at least - have to verify it when you select a new processor or a new compiler. I don't expect one of my existing compilers to change that behaviour - at least not without adding a very visible note in the release notes :)
Luckily, no chip manufacturer dares to step away från n*8-sized integer data types, because of the very bad feedback they would get from all the people who made the incorrect assumption that their programs will not fail if run on a machine with a 7-bit or 9-bit char data type. If they do add unusual data types, they add them as complements to more standard data types.
One of the first things you should do when looking for a new compiler, is to get your hands on the documentation about their take on the implementation-specific parts of the standard. You want to know if there are significant limits in # of nested if statements, number of case statements in a switch, if you will be able to nest multiple include files, if they have the usual include files (complete with expected contents) etc.
In the same way, you have to make sure if a selected processor has a general stack implementation, or if it may have a hard-coded return stack with a limited # of return etnries. You want to know if it can index data - and to what degree. You want to know if it will glow like Chernobyl or if it has reasonable power-save modes. Some details you will look up. Some details you will forget to look up. Some details you will assume to be ok, and will ignore checking up on. Checking up on everything requires perfect documentation, perfect memory and almost infinite amounts of time.
Why do you not read it all When I complained about it to one compiler maker, I was informed "there is nothing in ANSI C about this". I never checked, what good does it do to state "there is something in ANSI C about this", if your program does not work because of such.
I would claim that ANY multiword byte compiler should, at least, warn when a memory location is "typecasted up" I really do not give ahoot if it is ANSI C or not, it is dead easy for a compiler to 'see' that "a memory location is "typecasted up" and an (optional) warning would make the tool much more useful.
I care about good tools, if the toolmalker decides to hide behind ANSI C that is just too bad.
Sadly you do seem to have a lot of experience of bugs which you should never have introduced into the code in the first place. When being a member of groups, I have most often been "the debugger" thus your uttely stupid assumption that bugs I have seen were those I "have introduced into the code in the first place" is completely false.
Your assumption when something doesn't work as you expect is that the problem lies with the tools Where on earth did you get that impression? Of course in a toolmakers forum tools are the main subject of discussion, it evidently takes a smoked sardine to ASS U ME that limiting a discussion to the subject means that there are no other subjects.
But you - at least - have to verify it when you select a new processor or a new compiler. Of, course; however, I wrote "every time"
Luckily, no chip manufacturer dares to step away från n*8-sized integer data types, because of the very bad feedback they would get from all the people who made the incorrect assumption that their programs will not fail if run on a machine with a 7-bit or 9-bit char data type. If they do add unusual data types, they add them as complements to more standard data types. I would not know about chips, but Univac and (some) DEC machines use 6 bit bytes.
PS "från" slipped into your post, do you write in Swedish first or did a word just slip in ?
No two-step translation involved. However, I sometimes gets parity bit errors - especially when someone comes in and wants to talk to me in the middle of writing :)
Sw: från = Eng: from. They start the same, the same number of letters and similar pronounciation.
IBM had 36-bit big iron, so they impplemented 4x 9-bit characters or 5x 7-bit characters.
I really do not give ahoot if it is ANSI C or not
if the toolmalker decides to hide behind ANSI C that is just too bad.
ANSI 'C', now ISO 'C', is the 'C' language. In a recent thread you demonstrated that you didn't even know how a 'for' statement worked, so I guess it should come as no surprise that you can't grasp that simple fact.
whatever does you snide reply have to do with the fact that I posted "I care about good tools" which you left out in your quote.
What I said, and you decided to overlook, was that if it is possible to put out a warning for risky code (in this case "risky on the particular platdoem") the tool should do so whether it has anything to do with the C standard or not
Your other snide remark re a for. For your information I actually posted that I knew how a for loop worked, just wanted to make sure of one particular fact where the text in the standard was slightly unclear.
Why do you not just go bask to the sardine can someboduy let you out of
Nothing at all. That's why I left it out of the quote. Why do you ask?
You should only rely on a compiler to behave as specified by the standard. It is unreasonable for you to expect a compiler writer to try and anticipate every mistake someone who refuses to read the standard might make and issue a warning. Think about it: if you rely on a non-standard warning issued by a compiler you will have to read the documentation of every compiler you use to determine whether your incorrect code will work, generate a warning or simply fail. Why not just read the standard to determine whether your code is guaranteed to work and be done with it?
For your information I actually posted that I knew how a for loop worked, just wanted to make sure of one particular fact
Either you know something or you don't know something. Why would you need to 'make sure' of something you know?
where the text in the standard was slightly unclear.
Please quote this 'unclear text' from the standard. By the way, I fully expect you to be unable to do so.
I'm sure you're ego would prefer that, but sorry, you're out of luck.
How very amazing. You babble about "the standard" and what we are discussing is "a warning if some architecthure created easy to detect mistake". I have never had alignment problems, be that from typecasting or something else, but have in, at least 5 cases solved somebody elses problem by fixing alignment issues. There are legions of people that believe that a REAL C person should NEVER have even an inkling about what the hardware does, and for such (I have met many) a warning when an easily detectable architecturally dependent mistake is made, what is your opposition to asking for a warning there.
Please quote this 'unclear text' from the standard. By the way, I fully expect you to be unable to do so. sorry not to meet your expectations. the 'description' of a for states "3 is done as long as 2 is valid".
There is nothing said about "updated 3 is written back whatever 2 is"
in addition re an excerpt from you babble above whether your incorrect code will work who on earth cares if incorect code will work, incorect code IS incorrect code.
Think about it: if you rely on a non-standard warning issued by a compiler you will have to read the documentation of every compiler you use to determine whether your incorrect code will work, generate a warning or simply fail.
The question isn't if people rely on warnings. Some people do. But rely or not: We do know that they catch a number of problems. Is a compiler that helps catching problems good or bad?
People don't buy lint programs just because they are stupid or lazy. They know that they make mistakes. They know that projects can have multiple developers, and one developer may make assumptions that are not consistent with the views of the rest of the team. Not too many developers likes to scan every line checked in by all other developers, just in case they have done something stupid.
I try not to rely on my car warning if a door isn't fully closed. However, I still like that extra information. If I chose to distrust everyone, then I would always have to take a full walk around the car whenever someone have touched a door or have thrown in some extra luggage.
How very amazing. You babble about "the standard" and what we are discussing is "a warning if some architecthure created easy to detect mistake".
You misunderstand. If you write code that is guaranteed by the standard to work then you don't have to worry about or rely on the compiler to issue a warning. Simple.
I have never had alignment problems,
Ok, ok. I'll pretend to believe that all these mistakes you seem to have encountered have been made by other people. I'm sure everyone else will as well. Let's face it, you demonstrate your exemplary knowledge from the very basics of 'C' all the way up to complicated concepts like a 'for' statement with refreshing regularity.
There are legions of people that believe that a REAL C person should NEVER have even an inkling about what the hardware does,
A real 'C' person writes code that is guaranteed to work by the standard ie *code that will work on all architectures* wherever possible. Unnecessary use of knowledge of the architecture makes code non-portable, and depending on precisely what non-standard behaviour you are relying on potentially unreliable.
a warning when an easily detectable architecturally dependent mistake is made, what is your opposition to asking for a warning there.
I have no objection to the warning, and the compiler is entitled to issue one if it wishes. What I object to is your reliance on such warnings, or complaints about lack of them, rather than just doing the sensible thing and actually reading the language documentation to find out whether the code is guaranteed to work.
sorry not to meet your expectations. the 'description' of a for states "3 is done as long as 2 is valid".
Please quote the paragraph number, I'm having trouble finding that particular bit of text.
who on earth cares if incorect code will work, incorect code IS incorrect code.
That is precisely my point. You need to write correct code rather than relying on your 'suck it and see' approach.