Interfacing with, and getting return values from, a webpage

Discussion in 'C Programming' started by David Walker, Jun 28, 2003.

  1. David Walker

    David Walker Guest

    Hi
    I have a program which I need to interface with a webpage - the webpage will
    accept an input (probably a 'post' string from the program) and then will
    process it and needs to return a value. Is there an easy way to interface
    the program to do this? I have two questions:
    How can I call a webpage as simply as possible in c / c++ (preferably not
    using MFC etc) and pass a 'post' string to the page?
    How can I retrieve an array of values output by the webpage? I can output
    them in any format I like since i'm writing the webpage too - I was thinking
    just write the output page as a list of variables, basically as dynamically
    generated comma separated values data, but i'm not sure whether theres an
    easier or quicker way of doing it. Any ideas?
    As an added point, I don't want to actually open the webpage so that it is
    visible - it should remain hidden, so the user of the program is not aware
    of it being there.

    Thanks a lot

    David
     
    David Walker, Jun 28, 2003
    #1
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  2. David Walker

    Morris Dovey Guest

    David Walker wrote:

    > I have a program which I need to interface with a webpage - the webpage will
    > accept an input (probably a 'post' string from the program) and then will
    > process it and needs to return a value. Is there an easy way to interface
    > the program to do this? I have two questions:



    > How can I call a webpage as simply as possible in c / c++ (preferably not
    > using MFC etc) and pass a 'post' string to the page?


    [Posting from comp.lang.c]

    You can't do this in standard C - so this discussion is off-topic
    here. You need to ask this question in a newsgroup specific to
    your platform and ask about interfacing your client to the
    network. I don't think there's anything special that needs to be
    done on the server side other than to make sure that there's an
    HTML (or possibly plain text) file to retrieve.

    > How can I retrieve an array of values output by the webpage? I can output
    > them in any format I like since i'm writing the webpage too - I was thinking
    > just write the output page as a list of variables, basically as dynamically
    > generated comma separated values data, but i'm not sure whether theres an
    > easier or quicker way of doing it. Any ideas?


    Just issue an HTTP request using that mechanism provided by your
    platform. It's easy in a POSIX environment - but may or may not
    be in Windows (I don't know).

    > As an added point, I don't want to actually open the webpage so that it is
    > visible - it should remain hidden, so the user of the program is not aware
    > of it being there.


    This should make the job easy. Good luck. Please remember to drop
    comp.lang.c from further discussion.
    --
    Morris Dovey
    West Des Moines, Iowa USA
    C links at http://www.iedu.com/c
     
    Morris Dovey, Jun 28, 2003
    #2
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  3. [follow-ups set to comp.programming since this isn't a language question]

    David Walker wrote:

    > Hi
    > I have a program which I need to interface with a webpage - the webpage will
    > accept an input (probably a 'post' string from the program) and then will
    > process it and needs to return a value. Is there an easy way to interface
    > the program to do this? I have two questions:
    > How can I call a webpage as simply as possible in c / c++ (preferably not
    > using MFC etc) and pass a 'post' string to the page?


    There may be libraries around for making HTTP requests. If you can find
    one that you like it'll save you a lot of time and effort doing it yourself.

    Otherwise... read up on sockets and HTTP. There are a number of sockets
    tutorials around, and the HTTP protocol is well documented in RFC2616.

    The most often-quoted networking tutorial might help:

    http://www.ecst.csuchico.edu/~beej/guide/net/html/index.html

    > How can I retrieve an array of values output by the webpage? I can output
    > them in any format I like since i'm writing the webpage too - I was thinking
    > just write the output page as a list of variables, basically as dynamically
    > generated comma separated values data, but i'm not sure whether theres an
    > easier or quicker way of doing it. Any ideas?


    If the page is not designed to be viewed by a browser, then it doesn't
    need to be a web page at all. An HTTP server is quite capable of
    returning a text document, and if you're backing this with a CGI then
    you can just pump whatever text you like out to the client. Your
    program can then just process that text as you would any text file.

    Alternately you could have a variable in the HTTP query string which
    tells the CGI app to produce output in a specific format, with fallback
    to displayable HTML if the variable is not present or invalid.

    --
    Corey Murtagh
    The Electric Monk
    "Quidquid latine dictum sit, altum viditur!"
     
    Corey Murtagh, Jun 28, 2003
    #3
  4. David Walker

    CBFalconer Guest

    David Walker wrote:
    >
    > I have a program which I need to interface with a webpage - the
    > webpage will accept an input (probably a 'post' string from the
    > program) and then will process it and needs to return a value.
    > Is there an easy way to interface the program to do this? [snip]


    The following query and its returned value should explain why this
    is OT on c.l.c. FUPs set.

    [1] c:\c\malloc>grep -i -c webpage \stds\n869.txt
    0

    --
    Chuck F () ()
    Available for consulting/temporary embedded and systems.
    <http://cbfalconer.home.att.net> USE worldnet address!
     
    CBFalconer, Jun 29, 2003
    #4
  5. David Walker

    David Walker Guest

    > > I have a program which I need to interface with a webpage - the
    > > webpage will accept an input (probably a 'post' string from the
    > > program) and then will process it and needs to return a value.
    > > Is there an easy way to interface the program to do this? [snip]

    >
    > The following query and its returned value should explain why this
    > is OT on c.l.c. FUPs set.


    So if its so off topic in a C group, how about suggesting somewhere where it
    is on-topic then rather than just moaning. I have included
    comp.programming, but that seems to be far too general to have a chance of
    getting a good response.

    David
     
    David Walker, Jun 29, 2003
    #5
  6. David Walker

    CBFalconer Guest

    David Walker wrote:
    >
    > > > I have a program which I need to interface with a webpage - the
    > > > webpage will accept an input (probably a 'post' string from the
    > > > program) and then will process it and needs to return a value.
    > > > Is there an easy way to interface the program to do this? [snip]

    > >
    > > The following query and its returned value should explain why this
    > > is OT on c.l.c. FUPs set.

    >
    > So if its so off topic in a C group, how about suggesting somewhere
    > where it is on-topic then rather than just moaning. I have included
    > comp.programming, but that seems to be far too general to have a
    > chance of getting a good response.


    Your deliberate continuance of the off-topic posting will garner
    very little other than a plonking, which in turn seriously impedes
    your ability to get replies to future on-topic questions. Do you
    enter all conversations with screeches to address your unconnected
    concerns?

    --
    Chuck F () ()
    Available for consulting/temporary embedded and systems.
    <http://cbfalconer.home.att.net> USE worldnet address!
     
    CBFalconer, Jun 29, 2003
    #6
  7. David Walker

    Morris Dovey Guest

    David Walker wrote:
    >>> I have a program which I need to interface with a webpage
    >>> - the webpage will accept an input (probably a 'post'
    >>> string from the program) and then will process it and
    >>> needs to return a value. Is there an easy way to interface
    >>> the program to do this? [snip]

    >>
    >> The following query and its returned value should explain
    >> why this is OT on c.l.c. FUPs set.

    >
    > So if its so off topic in a C group, how about suggesting
    > somewhere where it is on-topic then rather than just moaning.
    > I have included comp.programming, but that seems to be far too
    > general to have a chance of getting a good response.


    [Again posting from comp.lang.c]

    David...

    I wrote: "You need to ask this question in a newsgroup specific
    to your platform and ask about interfacing your client to the
    network."

    If you'd like really specific redirection, you'll need to tell us
    what platform you're using for the client (Stratus/VOS,
    Windows/??, MAC/OS, ...)

    <MOAN>
    I wasn't moaning. I was giving you the best answer your query
    permits (and I /still/ haven't seen platform information.)
    </MOAN>
    --
    Morris Dovey
    West Des Moines, Iowa USA
    C links at http://www.iedu.com/c
     
    Morris Dovey, Jun 29, 2003
    #7
  8. Morris Dovey <> scribbled the following
    on comp.lang.c:
    > David Walker wrote:
    > >>> I have a program which I need to interface with a webpage
    > >>> - the webpage will accept an input (probably a 'post'
    > >>> string from the program) and then will process it and
    > >>> needs to return a value. Is there an easy way to interface
    > >>> the program to do this? [snip]
    > >>
    > >> The following query and its returned value should explain
    > >> why this is OT on c.l.c. FUPs set.

    > >
    > > So if its so off topic in a C group, how about suggesting
    > > somewhere where it is on-topic then rather than just moaning.
    > > I have included comp.programming, but that seems to be far too
    > > general to have a chance of getting a good response.


    > [Again posting from comp.lang.c]


    > David...


    > I wrote: "You need to ask this question in a newsgroup specific
    > to your platform and ask about interfacing your client to the
    > network."


    > If you'd like really specific redirection, you'll need to tell us
    > what platform you're using for the client (Stratus/VOS,
    > Windows/??, MAC/OS, ...)


    > <MOAN>
    > I wasn't moaning. I was giving you the best answer your query
    > permits (and I /still/ haven't seen platform information.)
    > </MOAN>


    He said "preferably not using MFC". MFC stands for Microsoft Foundation
    Classes. Now, you'll have to agree that *not* using MFC is pretty easy
    on *any* platform you can think of, and on quite many that you can't,
    but it is only relevant enough to mention if you happen to be using a
    platform that supports MFC, namely Microsoft Windows.

    --
    /-- Joona Palaste () ---------------------------\
    | Kingpriest of "The Flying Lemon Tree" G++ FR FW+ M- #108 D+ ADA N+++|
    | http://www.helsinki.fi/~palaste W++ B OP+ |
    \----------------------------------------- Finland rules! ------------/
    "The trouble with the French is they don't have a word for entrepreneur."
    - George Bush
     
    Joona I Palaste, Jun 29, 2003
    #8
  9. David Walker

    Morris Dovey Guest

    Joona I Palaste wrote:
    > Morris Dovey <> scribbled the following on
    > comp.lang.c:
    >
    >> David Walker wrote:
    >>>>> I have a program which I need to interface with a
    >>>>> webpage - the webpage will accept an input (probably a
    >>>>> 'post' string from the program) and then will process
    >>>>> it and needs to return a value. Is there an easy way
    >>>>> to interface the program to do this? [snip]
    >>>>
    >>>> The following query and its returned value should
    >>>> explain why this is OT on c.l.c. FUPs set.
    >>>
    >>> So if its so off topic in a C group, how about suggesting
    >>> somewhere where it is on-topic then rather than just
    >>> moaning. I have included comp.programming, but that seems
    >>> to be far too general to have a chance of getting a good
    >>> response.

    >
    >> [Again posting from comp.lang.c]

    >
    >> David...

    >
    >> I wrote: "You need to ask this question in a newsgroup
    >> specific to your platform and ask about interfacing your
    >> client to the network."

    >
    >> If you'd like really specific redirection, you'll need to
    >> tell us what platform you're using for the client
    >> (Stratus/VOS, Windows/??, MAC/OS, ...)

    >
    >> <MOAN> I wasn't moaning. I was giving you the best answer
    >> your query permits (and I /still/ haven't seen platform
    >> information.) </MOAN>

    >
    > He said "preferably not using MFC". MFC stands for Microsoft
    > Foundation Classes. Now, you'll have to agree that *not* using
    > MFC is pretty easy on *any* platform you can think of, and on
    > quite many that you can't, but it is only relevant enough to
    > mention if you happen to be using a platform that supports
    > MFC, namely Microsoft Windows.


    Joona...

    Thanks for straightening me out. Come to think of it, I /have/
    heard of Microsoft Foundation Classes (but have never studied or
    used 'em in anything I've written.)

    Then would news:comp.os.ms-windows.programmer.win32 (from Billy
    Chambless' "Welcome to cmp.lang.c" message) be an appropriate
    newsgroup for David to pursue his quest? Or are there better?

    (I'm beginning to wish I'd just said: "Off topic. Go away!" :cool:
    --
    Morris Dovey
    West Des Moines, Iowa USA
    C links at http://www.iedu.com/c
     
    Morris Dovey, Jun 29, 2003
    #9
  10. David Walker

    Malcolm Guest

    OT: MFC

    "Morris Dovey" <> wrote in message
    >
    > Thanks for straightening me out. Come to think of it, I /have/
    > heard of Microsoft Foundation Classes (but have never studied or
    > used 'em in anything I've written.)
    >

    MFC is formally a C++ library for writing Windows GUIs, but in fact it is a
    point-and-click method of automatically generating code. It is quite
    effective in getting complex interfaces up on screen in a short time, but an
    MFC program is no longer a human-readable C++ program, and it is part of
    Microsoft's wicked plot to destroy C++ and prevent any programs being ported
    from Windows to other systems.
     
    Malcolm, Jun 29, 2003
    #10
  11. David Walker

    Phlip Guest

    Re: MFC

    Malcolm wrote:
    >
    > "Morris Dovey" <> wrote in message
    > >
    > > Thanks for straightening me out. Come to think of it, I /have/
    > > heard of Microsoft Foundation Classes (but have never studied or
    > > used 'em in anything I've written.)
    > >

    > MFC is formally a C++ library for writing Windows GUIs, but in fact it is

    a
    > point-and-click method of automatically generating code. It is quite
    > effective in getting complex interfaces up on screen in a short time, but

    an
    > MFC program is no longer a human-readable C++ program, and it is part of
    > Microsoft's wicked plot to destroy C++ and prevent any programs being

    ported
    > from Windows to other systems.


    Call that "vendor lockin". It's why MS won't support WTL, an ultra-light MFC
    replacement written in some MS engineer's spare time. WTL provides the same
    core features as MFC, but without coupling everything together. You can
    refactor a WTL program. Hence, MS won't make it an official part of their
    VC++ suite.

    --
    Phlip
    http://www.c2.com/cgi/wiki?TestFirstUserInterfaces
     
    Phlip, Jun 29, 2003
    #11
  12. David Walker

    dg Guest

    Re: MFC

    "Phlip" <> wrote in message
    news:bdno1e$...
    > Malcolm wrote:
    > >
    > > "Morris Dovey" <> wrote in message
    > > >
    > > > Thanks for straightening me out. Come to think of it, I /have/
    > > > heard of Microsoft Foundation Classes (but have never studied or
    > > > used 'em in anything I've written.)
    > > >

    > > MFC is formally a C++ library for writing Windows GUIs, but in fact it

    is
    > a
    > > point-and-click method of automatically generating code. It is quite
    > > effective in getting complex interfaces up on screen in a short time,

    but
    > an
    > > MFC program is no longer a human-readable C++ program, and it is part of
    > > Microsoft's wicked plot to destroy C++ and prevent any programs being

    > ported
    > > from Windows to other systems.

    ya forget mfc if you woant to write a win 32 app learn tha api (strangley
    enuff its simplaer then mfc to me cores im writeing asm as well and you just
    haf to)
     
    dg, Jun 30, 2003
    #12
  13. On 29 Jun 2003 17:10:20 GMT, in comp.lang.c , Joona I Palaste
    <> wrote:

    >He said "preferably not using MFC". MFC stands for Microsoft Foundation
    >Classes.


    No it doesn't - MFC is a class A psychedelic.

    >Now, you'll have to agree that *not* using MFC is pretty easy


    ha, you can say that, then obviously you've never had MFC cold
    turkey...
    :)

    (my point being, MFC is well enough known to windows programmers, but
    those of us from other backgrounds might not have a clue waht it is,
    adn thus not be able to infer some implementation from it)


    --
    Mark McIntyre
    CLC FAQ <http://www.eskimo.com/~scs/C-faq/top.html>
    CLC readme: <http://www.angelfire.com/ms3/bchambless0/welcome_to_clc.html>


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    Mark McIntyre, Jun 30, 2003
    #13
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