Page 2 - Pass by reference in CPP

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#16

December 26th, 2012, 06:51 AM

Revathi R

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I have done

bash-2.03# nm /opt/SUNWspro/prod/lib/CC4/libp/libC.a|grep -i "void __Cimpl::cplus_init()*"
bash-2.03#

#17

December 27th, 2012, 07:56 AM

Revathi R

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Hi

Will you explain what is the meaning of output of nm command

Regards
Revathi

#18

December 27th, 2012, 10:20 AM

salem

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There seems to be a general lack of being able to read manual pages.
http://unixhelp.ed.ac.uk/CGI/man-cgi?nm

One other point, you have different tools displaying C++ symbols in different styles.

Some tools display proper C++ names.

Quote:

Undefined first referenced
symbol in file
cerr ../../../../libs/lib/libgeneral.a(string.o)
unsafe_ostream::operator<<(long) ../../../../libs/lib/libgeneral.a(string.o)
operator delete(void*) msggen.o

Other tools display C++ mangled names

Quote:

__________________
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper

#19

December 27th, 2012, 11:40 PM

Revathi R

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Thanks

I have went through the Manpages.

My question is

http://inst.eecs.berkeley.edu/~selfpace/studyguide/9F.sg/Output/linker.errors.html

at that link i have read like when. a function call does not find the body during linking it gives error undefined first reference.

so when i am using

Code:

 nm libxyz.a 
[132] | 0| 0|NOTY |GLOB |0 |UNDEF |__adcds

Code:

String.C
#include<stdio.h>
#include <String.h>
#include <ctype.h>
void main()
{
cerr<<"";
}

when i compiled the code with CC compiler I could see .o file get generated.

.o is being used in the generation of xyz.a file,.a also generated.

when i ve seen

Code:

 nm xyz.a|grep "cerr"
[44]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[54]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[87]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[22]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[33]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[28]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[33]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[18]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[18]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[239]   |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[39]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[22]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[20]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[31]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[57]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[25]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[48]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[48]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[19]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[18]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[21]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[29]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[30]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[63]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[21]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[72]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr
[42]    |         0|       0|OBJT |GLOB |0    |UNDEF  |cerr

as cerr is function which has to come from header file
but it is saying UNDEF

MY dought

1.if cerr is not in header how code get compiled
2.does it mean like during linking phase it is looking for function body error thrown,header contains Prototype so during compilation time no error was thrown...
if 2 is right am i missing any file during linking

as i could clearly see when i have used 4.3 compiler no issues but 5.8 i am getting this issue

Regards,
Revathi.

#20

December 28th, 2012, 01:59 AM

salem

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The UNDEF's in one library just mean that you need another library to resolve the symbols.

So when the linker complains about "unresolved symbols", it's really telling you that you're missing a library somewhere.

The 'nm' tool allows you to see what libraries contain an unresolved symbol, and the library that contains the symbol itself.

Going back a couple of days, I suggest something like
nm libgeneral.a | grep -i WmExpSimple
nm libgeneral.a | grep -i Numeric
nm libgeneral.a | grep -i FunctionNode
to see if you can find WmExpSimpleNumericFunctionNode with a spelling mistake.

If you still can't find it, then look at your build process to see if the source file containing the implementation of WmExpSimpleNumericFunctionNode is actually compiled.

I feel like I'm going round in circles here.....

#21

December 28th, 2012, 03:33 AM

nrvvhjvx

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I am so glad this internet thing works and your article really helped me. Might take you up on that home advice you

#22

December 28th, 2012, 03:37 AM

Revathi R

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Credit goes to salem...

Thanks once again salem

#23

December 31st, 2012, 03:47 AM

Revathi R

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I ve got error like

Code:

Undefined                       first referenced
 symbol                             in file
void __Cimpl::cplus_init()        (command line)
_mcount                             /opt/SUNWspro/prod/lib/CC4/libp/libC.a(buffer.o)

when i have seen

Code:

 
nm libC.a|grep "_mcount"

I know that the reference is undefined i would like to know how can i trace the lib file that i ve to include

Is there any way i can use some command??
and see the declaration of it??

Thanks
Revathi R

#24

December 31st, 2012, 07:49 AM

Revathi R

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Code:

void __Cimpl::cplus_init()        (command line)

here it is not even mentioning the file where the problem is what is the meaning of command line

Page 2 - Pass by reference in CPP

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