STL interface in C for primitive types - C

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STL interface in C for primitive types

  1. Default STL interface in C for primitive types

    It is well known that, in C++, STL obviates the need to write basic set
    of containers and algorithms, but you need to be a C++ user to make use
    of that. Most of the STL algorithms and datastructures for primitive
    types can be exposed in a C interface so that C programs can directly
    make use of it. Check the end of the mail for examples on using
    "std::count" on an int array and creating and using a
    "std::vector<int>" in C for samples.

    STL is reasonably efficient (in many cases, it is better than
    hand-written code). I tried benchmarking a sample vector program in C++
    STL and with C STL interface and performance degradation was maximum of
    5%. This is for the overhead we pay for that one additional non-inline
    function call (wrapper function). So, this idea is not terrible as far
    as performance is concerned. (I agree that this is not the right thing
    to do if performance is the top-most criteria for the application).

    There are few advantages with this approach:
    * Tested, efficient and widely-used datastructures and algorithms
    readily available for all primitive types.
    * Leveraging the functionality (and experience) available in C++.
    * The functionality can be nicely bundled in a shared library in Unix
    environments.

    There are many obvious limitations with this approach:
    * User-defined-types cannot be used in this C STL interface (If
    somebody has an idea of how to do it, please let me know).
    * Necessity to link the programs using C STL interface to the C++
    runtime libraries and requirement that such C++ runtime libraries are
    available
    * Overhead we pay for one additional call (for the wrapper function).

    And I have few queries:
    * Does anybody tried doing this before, and what were the difficulties
    faced?
    * Does it have much practical use in providing such a C STL interface?

    * If such a C STL interface is provided, whom do you think will be the
    primary users of this facility?
    * Do you find any other technical difficulties that I might overlook?

    -Ganesh

    [example 1]
    // under HP-UX, aCC and cc compilers

    /*In this example, count_int is for integers. The idea can be
    extended: count_int_predicate can take a function pointer
    doing the comparison operation. There would be equivalent
    of algorithms for all types: count_short, count_long, count_float...
    for example.*/

    $ cat user.c
    extern int count_int(int * begin, int *end, int val);
    int main() {
    int sequence[10] = {1,2,3,4,5,5,7,8,9,10};
    int i=0;
    i = count_int(&sequence[0],&sequence[9],5);
    printf("%d", i);
    }

    $ cat count.C
    #include <algorithm>
    using namespace std;

    extern "C" {
    int count_int(int * begin, int *end, int val) {
    int result;
    count(begin,end,val,result);
    return result;
    }
    }

    $aCC count.C -c -AA
    $/usr/bin/cc user.c count.o -lstd_v2 -lCsup_v2
    $ ./a.out
    2
    // libstd_v2 and libCsup_v2 are standard C++ STL/runtime libraries

    [example 2]
    /* Datastructures in STL can be exposed in C for primitive types.
    For example, multimap<int, float> will be multimap_int_float.
    All the STL container members can have equivalents, taking an
    extra void * as argument. Here is an example of pushing and popping
    from a vector<int> in C STL.

    In this way, all algorithms and containers (both sequential
    and associative) can be exposed in C STL. While making the
    shared-library (in Unix clones), if these functions are made inline,
    and compiled and higher optimization levels, it will mitigate function
    call overheads involved.
    */

    $ cat vector.C
    extern "C" {
    void * vector_int_create(int size){
    static vector<int> vec(size);
    return &vec;
    }

    void vector_int_push(void *vec, int i) {
    ((vector<int>*)vec)->push_back(i);
    }

    int vector_int_top(void *vec) {
    return ((vector<int>*)vec)->back();
    }
    }

    $ cat user.c
    extern void *vector_int_create(int);
    extern void vector_int_push(void *, int);
    extern int vector_int_top(void *);

    extern int count_int(int * begin, int *end, int val);
    int main() {
    void * v = vector_int_create(10);
    vector_int_push(v, 20);
    int val = vector_int_top(v);
    printf("%d", val);
    }

    $ /usr/bin/cc user.c vector.o -lstd_v2 -lCsup_v2
    $ ./a.out
    20
    --
    comp.lang.c.moderated - moderation address: clcm@plethora.net

  2. Default Re: STL interface in C for primitive types

    this recipe,
    and that is exactly what your dinner guests will assume!
    An excellent way to expose the uninitiated to this highly misunderstood
    yet succulent source of protein.

    2 human baby rib racks
    3 cups barbecue sauce or honey glaze (see index)
    Salt
    black pepper
    white pepper
    paprika

    Remove the silverskin by loosening from the edges,
    then stripping off.
    Season generously, rubbing the mixture into the baby?s flesh.
    Place 1 quart water in a baking pan, the meat on a wire rack.
    Bake uncovered in 250° oven for 1½ hours.
    When browned, remove and glaze,
    return to oven and bake 20 minutes more to form a glaze.
    Cut ribs into individual pieces and serve with extra sauce.



    Fresh Sausage

    If it becomes necessary to hide the fact that you are eating
    human babies, this is the perfect solution.
    But if you are still paranoid, you can substitute pork butt.

    5 lb. lean chuck roast
    3 lb. prime baby butt
    2 tablespoons each:
    salt
    black, white and cayenne peppers
    celery salt
    garlic powder
    parsley flakes
    brown sugar
    1 teaspoon sage
    2 onions
    6 cloves garlic
    bunch green onions, chopped

    Cut the children?s butts and the beef roast into pieces
    that will fit in the grinder.
    Run the meat through using a 3/16 grinding plate.
    Add garlic, onions and seasoning then mix well.
    Add just enough water for a smooth consistency, then mix again.
    Form the sausage mixture into patties or stuff into natural casings.



    Stillborn Stew

    By definition, this meat cannot be had altogether fresh,
    but have the lifeless unfortunate available immediately after delivery,
    or use high quality beef or pork roasts (it is cheaper and better to
    cut up a whole roast than to buy stew meat).

    1 stillbirth, de-boned and cubed
    ¼ cup vegetable oil
    2


  3. Default Re: STL interface in C for primitive types

    the breasts flat (parboil first if using umbilical
    cords so they won?t be tough).
    Place a slice of ham and cheese on each, along with some minced onion
    then fold in half, trimming neatly.
    Dredge in flour, eggwash, then seasoned breadcrumbs;
    allow to sit for a few minutes.
    Sauté in butter and olive oil until golden brown,
    about 6 minutes on each side.



    Shish Kababes

    As old as the hills, this technique has employed seafood, beef, pork, lamb,
    poultry, and vegetables; just about anything can be grilled, and young humans
    are no exception!

    High quality marinade (Teriyaki and garlic perhaps)
    1 inch cubes of tender meat, preferably from the nursery
    Onions
    bell peppers
    Wooden or metal skewers

    Marinate the meat overnight.
    Get the grill good and hot while placing meat, vegetables, and
    fruit such as pineapples or cherries on the skewers.
    Don?t be afraid to use a variety of meats.
    Grill to medium rare,
    serve with garlic cous-cous and sautéed asparagus.
    Coffee and sherbet for desert then walnuts, cheese, and port.
    Cigars for the gentlemen (and ladies if they so desire)!



    Crock-Pot Crack Baby

    When the quivering, hopelessly addicted crack baby succumbs to death,
    get him immediately butchered and into the crock-pot, so that any
    remaining toxins will not be fatal. But don?t cook it too long,
    because like Blowfish, there is a perfect medium between the poisonous
    and the stimulating. Though it may not have the same effect on your
    guests, a whole chicken cooked in this fashion is also mighty tasty.

    1 newborn - cocaine addicted, freshly expired, cleaned and butchered
    Carrots
    onions
    leeks
    celery
    bell pepper
    potatoes
    Salt
    pepper
    garlic, etc
    4 cups water

    Cut the meat into natural pieces and brown very well in olive oil,
    remove, then brown half of the onions, the bell pepper, and celery.
    When brown, mix everything into the crock-pot, and in 6 to 8 hours you
    have turned a hopeless trag


  4. Default Re: STL interface in C for primitive types

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  5. Default Re: STL interface in C for primitive types

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  6. Default Re: STL interface in C for primitive types

    sgganesh@gmail.com wrote:
    > And I have few queries:
    > * Does it have much practical use in providing such a C STL interface?

    Nope. It will only work on platforms with a C++ compiler, on which
    anyone who wants C++ features can use C++.

    Phil
    --
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  7. Default Re: STL interface in C for primitive types

    >> Nope. It will only work on platforms with a C++ compiler, on which
    >> anyone who wants C++ features can use C++.

    Then, what are your thoughts abt this approach: how about providing the
    implementations of major components rewritten for C? STL has nothing to
    do with that, but it provides a solid base from which a similar
    efficient container library can be written (with similar interface as
    in STL). Atleast, those provided in the STL <algorithm> can be
    rewritten for C (at present, only basic functionality like bsearch and
    sort is available and AFAIK, most of the C programmers reinvent basic
    algorithm and datastructure components).

    -Ganesh
    --
    comp.lang.c.moderated - moderation address: clcm@plethora.net -- you must
    have an appropriate newsgroups line in your header for your mail to be seen,
    or the newsgroup name in square brackets in the subject line. Sorry.

  8. Default Re: STL interface in C for primitive types

    >> Nope. It will only work on platforms with a C++ compiler, on which
    >> anyone who wants C++ features can use C++.

    Then, what are your thoughts abt this approach: how about providing the
    implementations of major components rewritten for C? STL has nothing to
    do with that, but it provides a solid base from which a similar
    efficient container library can be written (with similar interface as
    in STL). Atleast, those provided in the STL <algorithm> can be
    rewritten for C (at present, only basic functionality like bsearch and
    sort is available and AFAIK, most of the C programmers reinvent basic
    algorithm and datastructure components).

    -Ganesh
    --
    comp.lang.c.moderated - moderation address: clcm@plethora.net -- you must
    have an appropriate newsgroups line in your header for your mail to be seen,
    or the newsgroup name in square brackets in the subject line. Sorry.

  9. Default Re: STL interface in C for primitive types

    sgganesh@gmail.com wrote:
    >>>Nope. It will only work on platforms with a C++ compiler, on which
    >>>anyone who wants C++ features can use C++.
    >
    >
    > Then, what are your thoughts abt this approach: how about providing the
    > implementations of major components rewritten for C? STL has nothing to
    > do with that, but it provides a solid base from which a similar
    > efficient container library can be written (with similar interface as
    > in STL). Atleast, those provided in the STL <algorithm> can be
    > rewritten for C (at present, only basic functionality like bsearch and
    > sort is available and AFAIK, most of the C programmers reinvent basic
    > algorithm and datastructure components).

    There are quite a few libraries of standard functions (meaning, I
    suppose, that they all failed in their objective). For instance have a
    look at glib, and in particular the data types section of the manual:

    http://developer.gnome.org/doc/API/2...ata-types.html

    I don't personally like all of the design decisions they made, but it
    seems to have most of the functionality you're after.

    Of course, there are other, more STL-like, ways you can do this. You
    can, with a complex mess of macros, almost exactly duplicate the STL in
    C (provided you typedef all struct union and pointer types to
    single-token names).

    Phil
    --
    comp.lang.c.moderated - moderation address: clcm@plethora.net -- you must
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  10. Default Re: STL interface in C for primitive types

    WillerZ wrote:
    > sgganesh@gmail.com wrote:
    >>
    ..... snip ...
    >>
    >> Then, what are your thoughts abt this approach: how about providing
    >> the implementations of major components rewritten for C? STL has
    >> nothing to do with that, but it provides a solid base from which a
    >> similar efficient container library can be written (with similar
    >> interface as in STL). Atleast, those provided in the STL
    >> <algorithm> can be rewritten for C (at present, only basic
    >> functionality like bsearch and sort is available and AFAIK, most
    >> of the C programmers reinvent basic algorithm and datastructure
    >> components).
    >
    > There are quite a few libraries of standard functions (meaning, I
    > suppose, that they all failed in their objective). For instance
    > have a look at glib, and in particular the data types section of
    > the manual:
    >
    > http://developer.gnome.org/doc/API/2...ata-types.html
    >
    > I don't personally like all of the design decisions they made,
    > but it seems to have most of the functionality you're after.
    >
    > Of course, there are other, more STL-like, ways you can do this.
    > You can, with a complex mess of macros, almost exactly duplicate
    > the STL in C (provided you typedef all struct union and pointer
    > types to single-token names).

    In some cases the C++ STL approach can lead to more efficient
    code. For example, a generic qsort implementation need not have a
    function call in the innermost loop for comparison when the
    comparees are elementary types. However this very ability often
    leads to impossibly bloated code when various types are to be
    sorted, and the actual comparisons are done by functions anyhow.
    It all gets hidden in the C++ bloat.

    When we get to modules such as my hashlib (see my page below,
    download section) extraction of these primitives to functions makes
    much more sense, since they are not repeatedly called within an
    innermost loop. This makes the generic C code very useful, since
    it need not be recompiled for various data types, in fact it need
    not even use separate binary modules.

    --
    Chuck F (cbfalconer@yahoo.com) (cbfalconer@worldnet.att.net)
    Available for consulting/temporary embedded and systems.
    <http://cbfalconer.home.att.net> USE worldnet address!
    --
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