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William Conquere
#1 / 13
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 Problem assigning function to function pointer I'm having problems with the below code.... FuncPtr ptr; /*FuncPtr is my typedef'd pointer to a function*/ ptr= sin; /*I thought that this would make the ptr point to the function in math.h*/ I get the following error when trying to compile this-
/tmp/cca112771.o: In function `main':
/tmp/cca112771.o(.text+0xcc9): undefined reference to `sin'
I have math.h #include 'd in my code.
I've tried *ptr=sin, but that doesn't work, it gives me an invalid lvalue in
assignment error.
I've also tried doing cc prints.c -lm, which unfortunately did not
work.
Any ideas?
Thanks.
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| Fri, 08 Mar 2002 03:00:00 GMT |
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Paul Lutu
#2 / 13
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Problem assigning function to function pointer Quote: > Any ideas?
Yes. Post your code. What form does your declaration for FuncPtr take? Is it:
typedef double (*FuncPtr) (double);
If it is, it should work (I tested it). It should accept sin as an argument,
assuming you really have "#include <math.h>" in your code.
--
Paul Lutus
www.arachnoid.com
Quote: > I'm having problems with the below code.... > FuncPtr ptr; /*FuncPtr is my typedef'd pointer to a function*/ > ptr= sin; /*I thought that this would make the ptr point to the > function in math.h*/ > I get the following error when trying to compile this-
> /tmp/cca112771.o: In function `main':
> /tmp/cca112771.o(.text+0xcc9): undefined reference to `sin'
> I have math.h #include 'd in my code.
> I've tried *ptr=sin, but that doesn't work, it gives me an invalid lvalue
in
> assignment error.
> I've also tried doing cc prints.c -lm, which unfortunately did not
> work.
> Any ideas?
> Thanks.
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| Fri, 08 Mar 2002 03:00:00 GMT |
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Bill Tic
#3 / 13
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Problem assigning function to function pointer That is exactly my definition- I'm including math.h and it still does not work. This is blowing my mind.
Quote: > > Any ideas? > Yes. Post your code. What form does your declaration for FuncPtr take?
> Is it:
> typedef double (*FuncPtr) (double);
> If it is, it should work (I tested it). It should accept sin as an
argument,
> assuming you really have "#include <math.h>" in your code.
> --
> Paul Lutus
> www.arachnoid.com
> > I'm having problems with the below code....
> > FuncPtr ptr; /*FuncPtr is my typedef'd pointer to a function*/
> > ptr= sin; /*I thought that this would make the ptr point to the
> > function in math.h*/
> > I get the following error when trying to compile this-
> > /tmp/cca112771.o: In function `main':
> > /tmp/cca112771.o(.text+0xcc9): undefined reference to `sin'
> > I have math.h #include 'd in my code.
> > I've tried *ptr=sin, but that doesn't work, it gives me an invalid
lvalue
> in
> > assignment error.
> > I've also tried doing cc prints.c -lm, which unfortunately did not
> > work.
> > Any ideas?
> > Thanks.
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| Fri, 08 Mar 2002 03:00:00 GMT |
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John Winte
#4 / 13
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Problem assigning function to function pointer
Quote:
>That is exactly my definition- I'm including math.h and it still does not
>work.
>This is blowing my mind.
Take it in stages. Write a small piece of code which invokes sin(). See if that compiles and links. If it doesn't then your problem has nothing to do with the pointer business. If it does, try adding the pointer stuff to the test program. Does that work? If so, remove the invocation of sin() and try again. Somewhere along the line you'll probably realise where it's going
wrong.
HTH
John
--
John Winters. Wallingford, Oxon, England.
The Linux Emporium - a source for Linux CDs in the UK
See http://www.linuxemporium.co.uk/
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| Fri, 08 Mar 2002 03:00:00 GMT |
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Bill Tic
#5 / 13
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Problem assigning function to function pointer Ok- I tried your excellent suggestion. Any reference to sin(x) gives me the same error as I got before. I have #include <math.h> in the program. I'm fairly confused. Thanks
Quote:
> >That is exactly my definition- I'm including math.h and it still does not > >work. > >This is blowing my mind. > Take it in stages. Write a small piece of code which invokes sin().
> See if that compiles and links. If it doesn't then your problem has
> nothing to do with the pointer business. If it does, try adding the
> pointer stuff to the test program. Does that work? If so, remove
> the invocation of sin() and try again.
> Somewhere along the line you'll probably realise where it's going
> wrong.
> HTH
> John
> --
> John Winters. Wallingford, Oxon, England.
> The Linux Emporium - a source for Linux CDs in the UK
> See http://www.linuxemporium.co.uk/
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| Fri, 08 Mar 2002 03:00:00 GMT |
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Gergo Bara
#6 / 13
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Problem assigning function to function pointer Quote:
>Ok- I tried your excellent suggestion.
>Any reference to sin(x) gives me the same error as I got before.
>I have #include <math.h> in the program.
Now is the time to post your sample code and the exact command you use to invoke your compiler. And consider (cross)posting to your compiler's newsgroup. Gergo
--
Then there was the Formosan bartender named Taiwan-On.
GU d- s:+ a--- C++>$ UL+++ P>++ L+++ E>++ W+ N++ o? K- w--- !O !M !V
PS+ PE+ Y+ PGP+ t* 5+ X- R>+ tv++ b+>+++ DI+ D+ G>++ e* h! !r !y+
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| Fri, 08 Mar 2002 03:00:00 GMT |
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Bill Tic
#7 / 13
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Problem assigning function to function pointer Thanks all, I got the answer- I was incorrectly calling my compiler. Thanks a lot, Bill
Quote: > I'm having problems with the below code.... > FuncPtr ptr; /*FuncPtr is my typedef'd pointer to a function*/ > ptr= sin; /*I thought that this would make the ptr point to the > function in math.h*/ > I get the following error when trying to compile this-
> /tmp/cca112771.o: In function `main':
> /tmp/cca112771.o(.text+0xcc9): undefined reference to `sin'
> I have math.h #include 'd in my code.
> I've tried *ptr=sin, but that doesn't work, it gives me an invalid lvalue
in
> assignment error.
> I've also tried doing cc prints.c -lm, which unfortunately did not
> work.
> Any ideas?
> Thanks.
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| Fri, 08 Mar 2002 03:00:00 GMT |
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Lawrence Kir
#8 / 13
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Problem assigning function to function pointer
Quote:
>> Ok- I tried your excellent suggestion.
>> Any reference to sin(x) gives me the same error as I got before.
>> I have #include <math.h> in the program.
>> I'm fairly confused.
>> Thanks
>If you are using some flavor of UNIX, Linux, or if you are using GCC, then:
>Add the command line flag -lm.
The command line that the original poster used already contained -lm (at the end of the line too). Quote: >If you are using an older compiler, try adding something the compiler will
>recognize as floating point, like:
>double d = 1.5*3.;
>It's a FAQ.
But the OP already seems to have implemented the advice in the FAQ (or at least as far as we can see without seeing the code). --
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| Fri, 08 Mar 2002 03:00:00 GMT |
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Greg Mart
#9 / 13
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Problem assigning function to function pointer On Mon, 20 Sep 1999 17:25:24 -0700, "Bill Tice" Quote:
>Thanks all,
>I got the answer- I was incorrectly calling my compiler.
>Thanks a lot,
Yes it's true you should always properly address your compiler. I call mine Mr. gcc. I believe it finds anything else insulting. My computer on the other hands responds better to pet names. Regards, Greg "the daemon made me do it" Martin
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| Sat, 09 Mar 2002 03:00:00 GMT |
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dbin
#10 / 13
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Problem assigning function to function pointer Quote:
>I'm having problems with the below code.... > FuncPtr ptr; /*FuncPtr is my typedef'd pointer to a function*/ > ptr= sin; /*I thought that this would make the ptr point to the >function in math.h*/ >I get the following error when trying to compile this-
>/tmp/cca112771.o: In function `main':
>/tmp/cca112771.o(.text+0xcc9): undefined reference to `sin'
>I have math.h #include 'd in my code.
>I've tried *ptr=sin, but that doesn't work, it gives me an invalid lvalue in
>assignment error.
>I've also tried doing cc prints.c -lm, which unfortunately did not
>work.
>Any ideas?
>Thanks.
including the header is not enough.. are you also linking in the lib? perhaps.. -dlibmath
--
*/ unmatched closing comment
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| Sat, 09 Mar 2002 03:00:00 GMT |
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Richard Heathfiel
#11 / 13
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Problem assigning function to function pointer
<snip>
Quote: > Greg "the daemon made me do it" Martin
Go stick it up your nose. ;-)
--
Richard Heathfield
"Usenet is a strange place." - Dennis M Ritchie, 29 July 1999.
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| Sat, 09 Mar 2002 03:00:00 GMT |
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dbin
#12 / 13
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Problem assigning function to function pointer Quote:
>>I'm having problems with the below code....
>> FuncPtr ptr; /*FuncPtr is my typedef'd pointer to a function*/
>> ptr= sin; /*I thought that this would make the ptr point to the
>>function in math.h*/
>>I get the following error when trying to compile this-
>>/tmp/cca112771.o: In function `main':
>>/tmp/cca112771.o(.text+0xcc9): undefined reference to `sin'
>>I have math.h #include 'd in my code.
>>I've tried *ptr=sin, but that doesn't work, it gives me an invalid lvalue in
>>assignment error.
>>I've also tried doing cc prints.c -lm, which unfortunately did not
>>work.
>>Any ideas?
>>Thanks.
>including the header is not enough..
>are you also linking in the lib?
>perhaps.. -dlibmath
rereads the original post to see if His brilliant (NOT) suggestion was appreciated perhaps -lm :-| doh!
--
*/ unmatched closing comment
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| Sat, 09 Mar 2002 03:00:00 GMT |
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