Hi all,I am new to KDB development, currrently I have two questions onInterfacing and Exterfacing KDB with C.While reading the example and test the sample program myself, I foundout that I am not able to pass two parameters into a function like:K foo(K x, K y){…}if I want to use this C function in Q with four parameters: oneinteger list, one string list, one integer and one long value, how canI achieve it??And my second question is when I pass a list to C function like this:K foo(K x){…}, how can I read all the elements from list? And isthere any efficient way to pass a K type list to a C type array,forexample int* or int from a int list in KDB??Thanks
Anybody knows how to work it out?
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Date: Fri, 27 May 2011 01:37:08 -0400
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Your questions can be answered with a careful reading of the following two p=
ages:=20
https://code.kx.com/trac/wiki/Cookbook/ExtendingWithC
https://code.kx.com/trac/wiki/Cookbook/InterfacingWithC
Im not exactly sure what you mean by not being able to pass in two, yet you w=
ant to pass in four, but here’s what you can do:
1) have the function accept a dictionary or a list and pass all of your para=
meters in that way i.e.
K foo(K x) {…}
2) give each input its own argument i.e.
K foo(K x, K y, K z, K w) {…}
To access an array of a particular type, see the interfacing with C page and=
the large chart which contains types and vector accessors on it.
Once you know the accessors/how they work you can easily extract the data to=
a c array if you want.
Hi Timothy,Thanks for your reply.I have tried the methods from the two pages of cookbook. But I stillhave some problem with it.The function I want to implement should be able to handle three lists:integer, float(c double) and char.and currently, I have written a C function like:K myFun(K x, K y){ printf(“%i\n”,kI(x)[0]); printf(“%i\n”,kI(x)[1]); printf(“%i\n”,kF(y)[0]); printf(“%i\n”,kF(y)[1]); //printf(“%i\n”,kI(y)[0]); //printf(“%i\n”,kI(y)[1]); return ki((I)0);}in which the x accept a integer list and y accept a float(c double)listand I call them in q by:q>a:1 2q>b:5 3.9q>myFun a band I got a type errorThen I have tried second setting:I have tried to pass in two integer list while I uncomment line 6,7with line 4,5 comment:q>a:1 2q>b:3 4q>myFun[a;b]'rankq>myFun a bq>-2147483648q>-2147483648q>65648q>79695952which seems the address pointerI either got a rank error or some pointer addressin this case, how can I pass into lists in K x and K y into thefunction.Also, if I pass in something as following in the second setting:q>myFun 5 4 3 2 1it returns me:546564879695952May I ask why is it happen and how can I solve it?really appreciate for your helpOn 5??27??, ?U??1??37??, Timothy Rieder <trie…> wrote:> Your questions can be answered with a careful reading of the following two pages:>> https://code.kx.com/trac/wiki/Cookbook/ExtendingWithC>> https://code.kx.com/trac/wiki/Cookbook/InterfacingWithC>> Im not exactly sure what you mean by not being able to pass in two, yet you want to pass in four, but here’s what you can do:>> 1) have the function accept a dictionary or a list and pass all of your parameters in that way i.e.>> K foo(K x) {…}>> 2) give each input its own argument i.e.>> K foo(K x, K y, K z, K w) {…}>> To access an array of a particular type, see the interfacing with C page and the large chart which contains types and vector accessors on it.>> Once you know the accessors/how they work you can easily extract the data to a c array if you want.>> On May 25, 2011, at 11:35 AM, tchan <qgpx2…> wrote:>>>> > Hi all,>> > I am new to KDB development, currrently I have two questions on> > Interfacing and Exterfacing KDB with C.> > While reading the example and test the sample program myself, I found> > out that I am not able to pass two parameters into a function like:> > K foo(K x, K y){…}> > if I want to use this C function in Q with four parameters: one> > integer list, one string list, one integer and one long value, how can> > I achieve it??>> > And my second question is when I pass a list to C function like this:> > K foo(K x){…}, how can I read all the elements from list? And is> > there any efficient way to pass a K type list to a C type array,for> > example int* or int from a int list in KDB??>> > Thanks>> > –> >
Submitted via Google Groups</qgpx2…></trie…>
The type error comes from trying to apply b to a with this notation myFun a b.
You should call it with myFun[a;b]
The rank error comes from trying to call the c function with more arguments than it expects. When you bind the c function to q, you use
myFun:nameoflibfile 2:(nativeFunctionName;numberOfArgs)
I expect you have 1 for numberOfArgs where as you need 2 for your example.
thanks
2011/5/30 tchan <qgpx2006@gmail.com>
Hi Timothy,
Thanks for your reply.
I have tried the methods from the two pages of cookbook. But I still
have some problem with it.The function I want to implement should be able to handle three lists:
integer, float(c double) and char.and currently, I have written a C function like:
K myFun(K x, K y){
printf(“%i\n”,kI(x)[0]);
printf(“%i\n”,kI(x)[1]);
printf(“%i\n”,kF(y)[0]);
printf(“%i\n”,kF(y)[1]);
//printf(“%i\n”,kI(y)[0]);
//printf(“%i\n”,kI(y)[1]);
return ki((I)0);
}in which the x accept a integer list and y accept a float(c double)
list
and I call them in q by:
q>a:1 2
q>b:5 3.9
q>myFun a band I got a type error
Then I have tried second setting:
I have tried to pass in two integer list while I uncomment line 6,7
with line 4,5 comment:q>a:1 2
q>b:3 4
q>myFun[a;b]
'rankq>myFun a b
q>-2147483648
q>-2147483648
q>65648
q>79695952
which seems the address pointerI either got a rank error or some pointer address
in this case, how can I pass into lists in K x and K y into the
function.
Also, if I pass in something as following in the second setting:
q>myFun 5 4 3 2 1it returns me:
5
4
65648
79695952May I ask why is it happen and how can I solve it?
really appreciate for your help
Hi Charles,Really thanks for your adviceTomOn 5?30?, ??3?11?, Charles Skelton <char…> wrote:> The type error comes from trying to apply b to a with this notation myFun a> b.>> You should call it with myFun[a;b]>> The rank error comes from trying to call the c function with more arguments> than it expects. When you bind the c function to q, you use>> myFun:nameoflibfile 2:(nativeFunctionName;numberOfArgs)>> I expect you have 1 for numberOfArgs where as you need 2 for your example.>> thanks>> 2011/5/30 tchan <qgpx2…>>>>> > Hi Timothy,>> > Thanks for your reply.>> > I have tried the methods from the two pages of cookbook. But I still> > have some problem with it.>> > The function I want to implement should be able to handle three lists:> > integer, float(c double) and char.>> > and currently, I have written a C function like:> > K myFun(K x, K y){> > printf(“%i\n”,kI(x)[0]);> > printf(“%i\n”,kI(x)[1]);> > printf(“%i\n”,kF(y)[0]);> > printf(“%i\n”,kF(y)[1]);> > //printf(“%i\n”,kI(y)[0]);> > //printf(“%i\n”,kI(y)[1]);> > return ki((I)0);> > }>> > in which the x accept a integer list and y accept a float(c double)> > list> > and I call them in q by:> > q>a:1 2> > q>b:5 3.9> > q>myFun a b>> > and I got a type error>> > Then I have tried second setting:> > I have tried to pass in two integer list while I uncomment line 6,7> > with line 4,5 comment:>> > q>a:1 2> > q>b:3 4> > q>myFun[a;b]> > 'rank>> > q>myFun a b> > q>-2147483648> > q>-2147483648> > q>65648> > q>79695952> > which seems the address pointer>> > I either got a rank error or some pointer address> > in this case, how can I pass into lists in K x and K y into the> > function.> > Also, if I pass in something as following in the second setting:> > q>myFun 5 4 3 2 1>> > it returns me:> > 5> > 4> > 65648> > 79695952>> > May I ask why is it happen and how can I solve it?>> > really appreciate for your help>> > On 5?27?, ??1?37?, Timothy Rieder <trie…> wrote:> > > Your questions can be answered with a careful reading of the following> > two pages:>> > >https://code.kx.com/trac/wiki/Cookbook/ExtendingWithC>> > >https://code.kx.com/trac/wiki/Cookbook/InterfacingWithC>> > > Im not exactly sure what you mean by not being able to pass in two, yet> > you want to pass in four, but here’s what you can do:>> > > 1) have the function accept a dictionary or a list and pass all of your> > parameters in that way i.e.>> > > K foo(K x) {…}>> > > 2) give each input its own argument i.e.>> > > K foo(K x, K y, K z, K w) {…}>> > > To access an array of a particular type, see the interfacing with C page> > and the large chart which contains types and vector accessors on it.>> > > Once you know the accessors/how they work you can easily extract the data> > to a c array if you want.>> > > On May 25, 2011, at 11:35 AM, tchan <qgpx2…> wrote:>> > > > Hi all,>> > > > I am new to KDB development, currrently I have two questions on> > > > Interfacing and Exterfacing KDB with C.> > > > While reading the example and test the sample program myself, I found> > > > out that I am not able to pass two parameters into a function like:> > > > K foo(K x, K y){…}> > > > if I want to use this C function in Q with four parameters: one> > > > integer list, one string list, one integer and one long value, how can> > > > I achieve it??>> > > > And my second question is when I pass a list to C function like this:> > > > K foo(K x){…}, how can I read all the elements from list? And is> > > > there any efficient way to pass a K type list to a C type array,for> > > > example int* or int from a int list in KDB??>> > > > Thanks>> > > > –> > > > You received this message because you are subscribed to the Google> > Groups “Kdb+ Personal Developers” group.> > > > To post to this group, send email to personal-kdbplus@googlegroups.com> > .> > > > To unsubscribe from this group, send email to> > personal-kdbplus+unsubscribe@googlegroups.com.> > > > For more options, visit this group athttp://> > groups.google.com/group/personal-kdbplus?hl=en.- ??? ->> > > - ??? ->> > –> >
Submitted via Google Groups</qgpx2…></trie…></qgpx2…></char…>