The difference between char a[6] and char *p=new char[6] ?

Discussion in 'C Programming' started by wwj, Nov 3, 2003.

  1. wwj

    wwj Guest

    Hi ,all

    I want to know the difference between char a[6] and char *p=new
    char[6] and the difference between the heap and the stack ,and if the
    char a[6] is corresponding to the stack in MEMORY,and char *p=new
    char[6] is corresponding to the heap of MEMORY.

    Give me some hint.
    THANK YOU.
    wwj, Nov 3, 2003
    #1
    1. Advertising

  2. In article <>,
    (wwj) wrote:

    > Hi ,all
    >
    > I want to know the difference between char a[6] and char *p=new
    > char[6] and the difference between the heap and the stack ,and if the
    > char a[6] is corresponding to the stack in MEMORY,and char *p=new
    > char[6] is corresponding to the heap of MEMORY.


    Could you have a very very close look at the name of the newsgroup you
    are posting to? Is the name of that newsgroup "comp.lang.c++"? If not,
    then you are posting your C++ questions to the wrong newsgroup.
    Christian Bau, Nov 3, 2003
    #2
    1. Advertising

  3. wwj wrote:
    > Hi ,all
    >
    > I want to know the difference between char a[6] and char *p=new
    > char[6]


    The difference is that the second statement has no meaning in C.
    C++ is the second group down the hall, on the the left...

    > and the difference between the heap and the stack,


    This has nothing to do with the C language.

    > and if the
    > char a[6] is corresponding to the stack in MEMORY,and char *p=new
    > char[6] is corresponding to the heap of MEMORY.


    Since the C language has no notion of stack or heap, and since the
    second statement has no meaning in C, we can't answer such a question.

    > Give me some hint.


    first hint : C and C++ are two different languages. please post on the
    appropriate newsgroup.

    second hint :

    #include <regulars_please_correct_me_if_necessary.h>

    C <ot>and C++</ot> have a notion of automatic memory and a notion of
    dynamic memory.

    Automatic memory is the default storage, and local variables are usually
    automatic. This means that memory is automatically allocated for these
    variable at the beginning of the block, and that this memory is
    automatically freed at the end of the block.

    Automatic memory *may* be, on *some* platforms, implemented with a stack.

    Dynamic memory is memory that is allocated on demand, with a special
    mechanism (in C, usually the 'malloc()' function, <ot>in C++ usually the
    'new' operator</ot>), and that must be freed by code - usually in C with
    the 'free()' function <ot>and in C++ with 'delete'</ot>). Not freeing
    dynamically allocated memory (usually) causes a 'memory leak'.

    Dynamic memory *may* be, on *some* platforms, implemented with a 'heap'.

    Third hint : please learn the difference between C and C++, choose the
    one you like, get yourself a *good* book on it, and post on the
    appropriate group - after you've read the group's FAQ.

    > THANK YOU.

    Please dont scream, it's hurting my ears.

    Bruno
    Bruno Desthuilliers, Nov 3, 2003
    #3
  4. wwj

    wwj Guest

    ......~~
    Christian Bau <> wrote in message news:<>...
    > In article <>,
    > (wwj) wrote:
    >
    > > Hi ,all
    > >
    > > I want to know the difference between char a[6] and char *p=new
    > > char[6] and the difference between the heap and the stack ,and if the
    > > char a[6] is corresponding to the stack in MEMORY,and char *p=new
    > > char[6] is corresponding to the heap of MEMORY.

    >
    > Could you have a very very close look at the name of the newsgroup you
    > are posting to? Is the name of that newsgroup "comp.lang.c++"? If not,
    > then you are posting your C++ questions to the wrong newsgroup.
    wwj, Nov 3, 2003
    #4
  5. wwj

    wwj Guest

    Bruno ,Anyway firstly I thank you ,it's my wrong to post it here and
    now yet I can not tell from c and c++ well. Then,I want to say that
    our world is developing ,all developing,and the language c not be
    invent from uk or by you or Christian Bau,ple you do not regulate(this
    word not proper) it or sneer at others (new one) or rave at others .
    Bruno Desthuilliers <> wrote in message news:<3fa61449$0$27023$>...
    > wwj wrote:
    > > Hi ,all
    > >
    > > I want to know the difference between char a[6] and char *p=new
    > > char[6]

    >
    > The difference is that the second statement has no meaning in C.
    > C++ is the second group down the hall, on the the left...
    >
    > > and the difference between the heap and the stack,

    >
    > This has nothing to do with the C language.
    >
    > > and if the
    > > char a[6] is corresponding to the stack in MEMORY,and char *p=new
    > > char[6] is corresponding to the heap of MEMORY.

    >
    > Since the C language has no notion of stack or heap, and since the
    > second statement has no meaning in C, we can't answer such a question.
    >
    > > Give me some hint.

    >
    > first hint : C and C++ are two different languages. please post on the
    > appropriate newsgroup.
    >
    > second hint :
    >
    > #include <regulars_please_correct_me_if_necessary.h>
    >
    > C <ot>and C++</ot> have a notion of automatic memory and a notion of
    > dynamic memory.
    >
    > Automatic memory is the default storage, and local variables are usually
    > automatic. This means that memory is automatically allocated for these
    > variable at the beginning of the block, and that this memory is
    > automatically freed at the end of the block.
    >
    > Automatic memory *may* be, on *some* platforms, implemented with a stack.
    >
    > Dynamic memory is memory that is allocated on demand, with a special
    > mechanism (in C, usually the 'malloc()' function, <ot>in C++ usually the
    > 'new' operator</ot>), and that must be freed by code - usually in C with
    > the 'free()' function <ot>and in C++ with 'delete'</ot>). Not freeing
    > dynamically allocated memory (usually) causes a 'memory leak'.
    >
    > Dynamic memory *may* be, on *some* platforms, implemented with a 'heap'.
    >
    > Third hint : please learn the difference between C and C++, choose the
    > one you like, get yourself a *good* book on it, and post on the
    > appropriate group - after you've read the group's FAQ.
    >
    > > THANK YOU.

    > Please dont scream, it's hurting my ears.
    >
    > Bruno
    wwj, Nov 3, 2003
    #5
  6. wwj <> scribbled the following:
    > Bruno ,Anyway firstly I thank you ,it's my wrong to post it here and
    > now yet I can not tell from c and c++ well. Then,I want to say that
    > our world is developing ,all developing,and the language c not be
    > invent from uk or by you or Christian Bau,ple you do not regulate(this
    > word not proper) it or sneer at others (new one) or rave at others .


    In other words, because neither Bruno or Christian invented C, this
    newsgroup can freely be abused by posting off-topic messages which don't
    concern C at all?

    --
    /-- Joona Palaste () ------------- Finland --------\
    \-- http://www.helsinki.fi/~palaste --------------------- rules! --------/
    "You could take his life and..."
    - Mirja Tolsa
    Joona I Palaste, Nov 3, 2003
    #6
  7. wwj

    Default User Guest

    wwj wrote:
    >
    > Bruno ,Anyway firstly I thank you ,it's my wrong to post it here and
    > now yet I can not tell from c and c++ well. Then,I want to say that
    > our world is developing ,all developing,and the language c not be
    > invent from uk or by you or Christian Bau,ple you do not regulate(this
    > word not proper) it or sneer at others (new one) or rave at others .



    Don't top-post. Your replies belong following properly trimmed quotes.


    This newsgroup has topicality guidelines, which will be enforced by all
    the regulars. Those two happened to be the first to correct you, others
    would certainly have if they hadn't.

    I suggest you apologize to the group and the two individuals for your
    poor behavior.




    Brian Rodenborn
    Default User, Nov 3, 2003
    #7
  8. wwj

    CBFalconer Guest

    Joona I Palaste wrote:
    > wwj <> scribbled the following:
    >
    > > Bruno ,Anyway firstly I thank you ,it's my wrong to post it here and
    > > now yet I can not tell from c and c++ well. Then,I want to say that
    > > our world is developing ,all developing,and the language c not be
    > > invent from uk or by you or Christian Bau,ple you do not regulate(this
    > > word not proper) it or sneer at others (new one) or rave at others .

    >
    > In other words, because neither Bruno or Christian invented C, this
    > newsgroup can freely be abused by posting off-topic messages which don't
    > concern C at all?


    wwj obviously has a language barrier, and is doing his/her best.
    So there is no need to pick at him. Simply drop it, and see what
    develops. He already explained he doesn't know the difference
    between C and C++, and obviously has not been told to lurk before
    posting.

    --
    Chuck F () ()
    Available for consulting/temporary embedded and systems.
    <http://cbfalconer.home.att.net> USE worldnet address!
    CBFalconer, Nov 3, 2003
    #8
  9. wwj

    wwj Guest

    i have said its my wrong to post it here !!!!!!!
    Joona I Palaste <> wrote in message
    > In other words, because neither Bruno or Christian invented C, this
    > newsgroup can freely be abused by posting off-topic messages which don't
    > concern C at all?
    wwj, Nov 4, 2003
    #9
  10. wwj

    wwj Guest

    why?why apologize for my poor behavior ?what is my poor behavior?
    Default User <> wrote in message news:<>...
    > Don't top-post. Your replies belong following properly trimmed quotes.
    >
    >
    > This newsgroup has topicality guidelines, which will be enforced by all
    > the regulars. Those two happened to be the first to correct you, others
    > would certainly have if they hadn't.
    >
    > I suggest you apologize to the group and the two individuals for your
    > poor behavior.
    >
    >
    >
    >
    > Brian Rodenborn
    wwj, Nov 4, 2003
    #10
  11. wwj

    Roose Guest

    Don't mind them, see some of the other threads:

    Asking if elements in struct arre zero
    "Mastering C Pointers"....
    Interview question !!!
    ANSI C compliance

    for a discussion of why you got jumped on so harshly. It is unfortunate
    that people are so rude to someone just seeking an answer to a simple
    question. One (non-sarcastic) post pointing out that it's off-topic is
    quite enough. No need for a pathetic display of severe personality defects.

    But yes your post has to do with C++, so unfortunately you won't get a good
    answer here. But let me try, to make up for the harsh treatment (flames be
    gone, it's off-topic anyway):

    char a[6], if declared in a function, is a character array on the stack,
    typically (flamers note: if I go into auto, it's going to take a lot more
    explanation than he cares to hear, so STFU)

    char *p = new char[6]; assigns to p a pointer to the beginning of 6
    bytes of dynamically allocated memory, typically located on the "heap" as
    you said

    Google for "stack" and some other stuff maybe "function" "compiler", if you
    don't know what a stack is. It's an abstract data type, and can be used to
    implement variables declared in a function in C. That is, it manages their
    automatic cleanup after the function exits. In contrast, you must
    explicitly call "delete p" in order to free the memory allocated by new --
    otherwise you have a memory leak.

    The difference is that they are basically different systems of managing
    memory. With a stack, you don't have to worry about cleaning up -- however
    the variable has limited scope. A variable on the heap persists as long as
    you need it, and you take responsibility for cleaning it up yourself.

    Roose



    "wwj" <> wrote in message
    news:...
    > why?why apologize for my poor behavior ?what is my poor behavior?
    > Default User <> wrote in message

    news:<>...
    > > Don't top-post. Your replies belong following properly trimmed quotes.
    > >
    > >
    > > This newsgroup has topicality guidelines, which will be enforced by all
    > > the regulars. Those two happened to be the first to correct you, others
    > > would certainly have if they hadn't.
    > >
    > > I suggest you apologize to the group and the two individuals for your
    > > poor behavior.
    > >
    > >
    > >
    > >
    > > Brian Rodenborn
    Roose, Nov 4, 2003
    #11
  12. Roose wrote:

    <snip>

    > But yes your post has to do with C++, so unfortunately you won't get a
    > good
    > answer here.


    He will, however, get a good answer in comp.lang.c++

    > But let me try, to make up for the harsh treatment (flames
    > be gone, it's off-topic anyway):


    Not only will he get a good answer in comp.lang.c++ but, also, any mistakes
    in that answer will stand a much better chance of correction if it is
    presented in the correct newsgroup.


    >
    > char a[6], if declared in a function, is a character array on the
    > stack,


    That is not necessarily true.

    > char *p = new char[6]; assigns to p a pointer to the beginning of 6
    > bytes of dynamically allocated memory, typically located on the "heap" as
    > you said


    No, it's a syntax error in C, which is the topic of this newsgroup.

    <snip>

    --
    Richard Heathfield :
    "Usenet is a strange place." - Dennis M Ritchie, 29 July 1999.
    C FAQ: http://www.eskimo.com/~scs/C-faq/top.html
    K&R answers, C books, etc: http://users.powernet.co.uk/eton
    Richard Heathfield, Nov 4, 2003
    #12
  13. wwj

    wwj Guest

    Ok,thanks Roose very much.You are a good person , goodness.

    In our here ,I learn from school that basiclly C++ is a extension of
    C,and C is a subset of C++,expcept some difference.Maybe it is that my
    teacher do not express that clearly or I do not understand that
    clearly.So sorry for everyone ,I wish this post ends the heartrending
    topic,and all not waster time on the confused quarrel.
    "Roose" <> wrote in message news:<rHIpb.13664$>...
    > Don't mind them, see some of the other threads:
    >
    > Asking if elements in struct arre zero
    > "Mastering C Pointers"....
    > Interview question !!!
    > ANSI C compliance
    >
    > for a discussion of why you got jumped on so harshly. It is unfortunate
    > that people are so rude to someone just seeking an answer to a simple
    > question. One (non-sarcastic) post pointing out that it's off-topic is
    > quite enough. No need for a pathetic display of severe personality defects.
    >
    > But yes your post has to do with C++, so unfortunately you won't get a good
    > answer here. But let me try, to make up for the harsh treatment (flames be
    > gone, it's off-topic anyway):
    >
    > char a[6], if declared in a function, is a character array on the stack,
    > typically (flamers note: if I go into auto, it's going to take a lot more
    > explanation than he cares to hear, so STFU)
    >
    > char *p = new char[6]; assigns to p a pointer to the beginning of 6
    > bytes of dynamically allocated memory, typically located on the "heap" as
    > you said
    >
    > Google for "stack" and some other stuff maybe "function" "compiler", if you
    > don't know what a stack is. It's an abstract data type, and can be used to
    > implement variables declared in a function in C. That is, it manages their
    > automatic cleanup after the function exits. In contrast, you must
    > explicitly call "delete p" in order to free the memory allocated by new --
    > otherwise you have a memory leak.
    >
    > The difference is that they are basically different systems of managing
    > memory. With a stack, you don't have to worry about cleaning up -- however
    > the variable has limited scope. A variable on the heap persists as long as
    > you need it, and you take responsibility for cleaning it up yourself.
    >
    > Roose
    >
    >
    >
    > "wwj" <> wrote in message
    > news:...
    > > why?why apologize for my poor behavior ?what is my poor behavior?
    > > Default User <> wrote in message

    > news:<>...
    > > > Don't top-post. Your replies belong following properly trimmed quotes.
    > > >
    > > >
    > > > This newsgroup has topicality guidelines, which will be enforced by all
    > > > the regulars. Those two happened to be the first to correct you, others
    > > > would certainly have if they hadn't.
    > > >
    > > > I suggest you apologize to the group and the two individuals for your
    > > > poor behavior.
    > > >
    > > >
    > > >
    > > >
    > > > Brian Rodenborn
    wwj, Nov 4, 2003
    #13
  14. wwj

    Richard Bos Guest

    (wwj) wrote:

    [ Don't top-post, please. Corrected. ]

    > "Roose" <> wrote in message news:<rHIpb.13664$>...
    > > char a[6], if declared in a function, is a character array on the stack,
    > > typically (flamers note: if I go into auto, it's going to take a lot more
    > > explanation than he cares to hear, so STFU)


    The point is that "automatic memory" is a higher-level concept, and
    therefore more useful to the reliable, foresightful programmer than "on
    the stack". In particular, automatic memory has properties that a stack
    need not have, and vice versa.
    Besides, automatic memory need not be kept in any stack. It's quite
    common, for example, for the smaller auto objects to reside in
    registers. Well-written C doesn't care about the difference, as long as
    auto objects function as the Standard says they should.

    > > char *p = new char[6]; assigns to p a pointer to the beginning of 6
    > > bytes of dynamically allocated memory, typically located on the "heap" as
    > > you said
    > >
    > > Google for "stack" and some other stuff maybe "function" "compiler", if you
    > > don't know what a stack is. It's an abstract data type,


    Not in this context, it isn't. _If_ automatic memory is placed in a
    stack, it's almost certainly a hardware one. Of course, it would be
    possible to write a C implementation for a LISP machine which puts its
    auto memory in a software stack, which would be an example of an ADT
    after all... and a well-written C program wouldn't care a jot about his
    detail.

    > > That is, it manages their automatic cleanup after the function exits.


    Erm, no. The demands of automatic memory do that. That's why it's called
    "automatic", see? Internally, the C implementation does a lot of byte
    shuffling whether your auto memory is on a stack or not; but the point
    is that this is hidden from you no matter how it is implemented.

    > > The difference is that they are basically different systems of managing
    > > memory. With a stack, you don't have to worry about cleaning up -- however
    > > the variable has limited scope.


    YM duration. Memory has no scope, identifiers have scope. It _is_
    possible to have allocated memory, with only one identifier pointing to
    it which has block scope, but with allocated duration which lasts beyond
    that scope - and this knowledge is important, because failure to
    recognise it often causes memory leaks. Like this:

    {
    int *a;
    a=malloc(100* sizeof *a);
    }

    Note that the pointer a has a scope of no larger than this single block
    - yet the memory it is made to point to has a duration beyond the
    block's execution time. In this case, this causes a memory leak. A
    single return a;, which affects neither the scope of the identifier nor,
    strictly speaking, the duration of the object, could solve the leak.

    > Ok,thanks Roose very much.You are a good person , goodness.


    I doubt that. His information, in any case, is dubious.

    > In our here ,I learn from school that basiclly C++ is a extension of
    > C,and C is a subset of C++,expcept some difference.


    That is, alas, a much-held view, but it's wrong. _Good_ C++ is
    fundamentally different from good C. It is, indeed, possible to write a
    restricted kind of C++ which looks like a restricted kind of C, but in
    the general case the result will be bad C, and AFAICT worse C++.

    > Maybe it is that my teacher do not express that clearly


    All too many teachers don't know what the blazes they are on about, and
    all too many teachers do indeed think that they know C == C++ minus
    classes, which is patently and obviously false.

    Richard
    Richard Bos, Nov 4, 2003
    #14
  15. wwj wrote:

    [OT] Please don't top-post (corrected)

    > Bruno Desthuilliers <> wrote in message news:<3fa61449$0$27023$>...
    >
    >>wwj wrote:
    >>
    >>>Hi ,all
    >>>
    >>>I want to know the difference between char a[6] and char *p=new
    >>>char[6]

    >>
    >>The difference is that the second statement has no meaning in C.
    >>C++ is the second group down the hall, on the the left...


    (snip)

    >>
    >>>and the difference between the heap and the stack,

    >>
    >>This has nothing to do with the C language.
    >>


    > Bruno ,Anyway firstly I thank you ,it's my wrong to post it here and
    > now yet I can not tell from c and c++ well.


    They are two distinct languages, even if they share some common parts.
    C++ as been designed to be as compatible as possible with the C language
    as it was by the time, so some C source may be compiled in C++ as is or
    with little modification, but still they are really two distinct languages.

    > Then,I want to say that
    > our world is developing ,all developing,and the language c not be
    > invent from uk or by you or Christian Bau,


    None of us three would claim to have invented this language.

    >ple you do not regulate(this
    > word not proper) it


    As regular readers (me) or regular posters (some other here) of this
    newsgroup, we do regulate it in order to keep a good signal/noise ratio.
    This (auto) regulation makes this group one of the best places around to
    learn C.

    >or sneer at others (new one) or rave at others .


    Ok, it's usenet here and we usually go straight to the point. I
    understand this may seem a bit harsh at first, but you'd better get used
    to it !-)

    According to the usenet standards, I think that my answer was quite
    polite, as I did take the time to explain why you were OT here and even
    tried to partially answer your question and give you some useful hints.

    Bruno
    Bruno Desthuilliers, Nov 4, 2003
    #15
  16. wwj

    Guest

    wwj <> wrote:

    > i have said its my wrong to post it here !!!!!!!


    These people don't care.

    You made an error (or errors) and now must be punished because you are
    not in the inner circle (http://tinyurl.com/8qpp). They make these same
    (non-C related) errors, but would never go after each other the same way
    they go after others.

    I would suggest that in the future you just ignore them when their
    comments refer to anything other then the C language or don't directly
    answer your question.

    However, they are quite knowledgeable about C and you should feel free
    to use this group to extract that knowledge whenever you feel the need.

    --
    , Nov 4, 2003
    #16
  17. wwj

    CBFalconer Guest

    wwj wrote:
    >
    > In our here ,I learn from school that basiclly C++ is a extension
    > of C,and C is a subset of C++,expcept some difference.Maybe it is
    > that my teacher do not express that clearly or I do not understand
    > that clearly.So sorry for everyone ,I wish this post ends the
    > heartrending topic,and all not waster time on the confused quarrel.


    You are still topposting, which means adding your answer
    **before** the quoted text. Your reply goes **after** any quoted
    text (or possibly intermixed), so that things read in a logical
    order. You should also snip any quotations not germane to your
    reply.

    Topposting is considered extremely rude in the better newsgroups,
    of which this is one.

    To correct a misconception, C++ is a different language than C. C
    is NOT a subset. If your teacher is telling you otherwise he is
    flat out WRONG. You may quote me to him if you wish, as it may
    not be politic to contradict him yourself.

    --
    Chuck F () ()
    Available for consulting/temporary embedded and systems.
    <http://cbfalconer.home.att.net> USE worldnet address!
    CBFalconer, Nov 4, 2003
    #17
  18. wwj

    Minti Guest

    Bruno Desthuilliers <> wrote in message news:<3fa61449$0$27023$>...
    > wwj wrote:
    > > Hi ,all
    > >
    > > I want to know the difference between char a[6] and char *p=new
    > > char[6]

    >
    > The difference is that the second statement has no meaning in C.
    > C++ is the second group down the hall, on the the left...
    >
    > > and the difference between the heap and the stack,

    >
    > This has nothing to do with the C language.
    >
    > > and if the
    > > char a[6] is corresponding to the stack in MEMORY,and char *p=new
    > > char[6] is corresponding to the heap of MEMORY.

    >
    > Since the C language has no notion of stack or heap, and since the
    > second statement has no meaning in C, we can't answer such a question.
    >
    > > Give me some hint.

    >
    > first hint : C and C++ are two different languages. please post on the
    > appropriate newsgroup.
    >
    > second hint :
    >
    > #include <regulars_please_correct_me_if_necessary.h>
    >
    > C <ot>and C++</ot> have a notion of automatic memory and a notion of
    > dynamic memory.
    >
    > Automatic memory is the default storage, and local variables are usually
    > automatic. This means that memory is automatically allocated for these
    > variable at the beginning of the block, and that this memory is
    > automatically freed at the end of the block.
    >
    > Automatic memory *may* be, on *some* platforms, implemented with a stack.
    >
    > Dynamic memory is memory that is allocated on demand, with a special
    > mechanism (in C, usually the 'malloc()' function, <ot>in C++ usually the
    > 'new' operator</ot>), and that must be freed by code - usually in C with
    > the 'free()' function <ot>and in C++ with 'delete'</ot>). Not freeing
    > dynamically allocated memory (usually) causes a 'memory leak'.
    >
    > Dynamic memory *may* be, on *some* platforms, implemented with a 'heap'.
    >
    > Third hint : please learn the difference between C and C++, choose the
    > one you like, get yourself a *good* book on it, and post on the
    > appropriate group - after you've read the group's FAQ.


    Wrong there are 3 types of memory in C and C++

    1) Automatic
    2) Dynamic
    3 and Static

    --
    Imanpreet Singh Arora
    isingh AT acm DOT org
    Minti, Nov 4, 2003
    #18
  19. wwj

    Minti Guest

    wrote in message news:<1g3wb6i.120yevw1ji5orwN%>...
    > wwj <> wrote:
    >
    > > i have said its my wrong to post it here !!!!!!!

    >
    > These people don't care.
    >
    > You made an error (or errors) and now must be punished because you are
    > not in the inner circle (http://tinyurl.com/8qpp). They make these same
    > (non-C related) errors, but would never go after each other the same way
    > they go after others.
    >
    > I would suggest that in the future you just ignore them when their
    > comments refer to anything other then the C language or don't directly
    > answer your question.
    >
    > However, they are quite knowledgeable about C and you should feel free
    > to use this group to extract that knowledge whenever you feel the need.
    >
    > --


    Wow you seem to allow all those 'killer bees' who just want to suck
    you for their own good. Thank you very much. This is a community. In
    every community be it dog or cat or lion or tiger or even human we
    tend to protect members of community. Look around you and see how many
    peopled do YOU listen too.

    "Hello my name is Imanpreet?"

    Will you respond..


    --
    Imanpreet Singh Arora
    isingh AT acm DOT org

    Proud to be a part of c.l.c community. BZzzzzzzzzzzzzzzzzzzzzzzzzzz
    Minti, Nov 4, 2003
    #19
  20. wwj

    Mike Wahler Guest

    "Minti" <> wrote in message
    news:...
    > Bruno Desthuilliers <> wrote in message

    news:<3fa61449$0$27023$>...
    > > wwj wrote:
    > > > Hi ,all
    > > >
    > > > I want to know the difference between char a[6] and char *p=new
    > > > char[6]

    > >
    > > The difference is that the second statement has no meaning in C.
    > > C++ is the second group down the hall, on the the left...
    > >
    > > > and the difference between the heap and the stack,

    > >
    > > This has nothing to do with the C language.
    > >
    > > > and if the
    > > > char a[6] is corresponding to the stack in MEMORY,and char *p=new
    > > > char[6] is corresponding to the heap of MEMORY.

    > >
    > > Since the C language has no notion of stack or heap, and since the
    > > second statement has no meaning in C, we can't answer such a question.
    > >
    > > > Give me some hint.

    > >
    > > first hint : C and C++ are two different languages. please post on the
    > > appropriate newsgroup.
    > >
    > > second hint :
    > >
    > > #include <regulars_please_correct_me_if_necessary.h>
    > >
    > > C <ot>and C++</ot> have a notion of automatic memory and a notion of
    > > dynamic memory.
    > >
    > > Automatic memory is the default storage,


    In block scope. Storage defined at file scope is has static
    storage duration by definition.

    > and local variables are usually
    > > automatic. This means that memory is automatically allocated for these
    > > variable at the beginning of the block, and that this memory is
    > > automatically freed at the end of the block.
    > >
    > > Automatic memory *may* be, on *some* platforms, implemented with a

    stack.
    > >
    > > Dynamic memory is memory that is allocated on demand, with a special
    > > mechanism (in C, usually the 'malloc()' function, <ot>in C++ usually the
    > > 'new' operator</ot>), and that must be freed by code - usually in C with
    > > the 'free()' function <ot>and in C++ with 'delete'</ot>). Not freeing
    > > dynamically allocated memory (usually) causes a 'memory leak'.
    > >
    > > Dynamic memory *may* be, on *some* platforms, implemented with a 'heap'.
    > >
    > > Third hint : please learn the difference between C and C++, choose the
    > > one you like, get yourself a *good* book on it, and post on the
    > > appropriate group - after you've read the group's FAQ.

    >
    > Wrong there are 3 types of memory


    That's 'storage duration'.

    >in C and C++
    >
    > 1) Automatic
    > 2) Dynamic
    > 3 and Static


    Yes there are, but I don't think Bruno's message was 'wrong'.

    The acknowledgement of the existence of apples and oranges
    does not imply denial of the existence of bananas. I didn't
    see Bruno say 'only' automatic and dynamic (actually the formal
    term for the latter is 'allocated' (6.2.4)).

    -Mike
    Mike Wahler, Nov 4, 2003
    #20
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