Databases
StackOverflow2013
Postsdbo
POHow to include a file only once / Prevent Function Redefinitions in old C API from C++ Program
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POHow to include a file only once / Prevent Function Redefinitions in old C API from C++ Program
    primarykey
    data
    text
    <p>I have a C++ program that HAS to use a C based API for a specific task. If I include only in to a single cpp in my program I have no problems at all. However if I include in to a header file (where I need to use some types) I get redefinition errors by the linker.</p> <p>This is due to a number of typedefs made in the external libraries (C header with compiled dll) header. I am looking for any possible solutions to this problem.</p> <p>When I search all I can seem to find is header guard stuff (and #pragma once) but these aren't the solution to the problem as what I am finding is multiple definitions in separate compilation units that are then conflicting whilst linking.</p> <p>I was thinking about extern but found that I am unable to use any types defined in the header as members in a C++ class, which is mostly what I am trying to do.</p> <pre><code>Output for building on Warning Level 4 Warning 1 warning C4273: 'getwchar' : inconsistent dll linkage c:\program files (x86)\microsoft visual studio 11.0\vc\include\stdio.h 615 1 project-test Warning 2 warning C4273: 'putwchar' : inconsistent dll linkage c:\program files (x86)\microsoft visual studio 11.0\vc\include\stdio.h 617 1 project-test Warning 3 warning C4273: 'getwchar' : inconsistent dll linkage c:\program files (x86)\microsoft visual studio 11.0\vc\include\stdio.h 615 1 project-test Warning 4 warning C4273: 'putwchar' : inconsistent dll linkage c:\program files (x86)\microsoft visual studio 11.0\vc\include\stdio.h 617 1 project-test Warning 5 warning C4100: 'data' : unreferenced formal parameter c:\users\ian\skydrive\documents\uni\finpro\projects\project-test\project-test\main.cpp 8 1 project-test Warning 6 warning C4100: 'event' : unreferenced formal parameter c:\users\ian\skydrive\documents\uni\finpro\projects\project-test\project-test\main.cpp 8 1 project-test Warning 7 warning C4100: 'widget' : unreferenced formal parameter c:\users\ian\skydrive\documents\uni\finpro\projects\project-test\project-test\main.cpp 8 1 project-test Warning 8 warning C4100: 'data' : unreferenced formal parameter c:\users\ian\skydrive\documents\uni\finpro\projects\project-test\project-test\main.cpp 15 1 project-test Warning 9 warning C4100: 'event' : unreferenced formal parameter c:\users\ian\skydrive\documents\uni\finpro\projects\project-test\project-test\main.cpp 15 1 project-test Warning 10 warning C4100: 'widget' : unreferenced formal parameter c:\users\ian\skydrive\documents\uni\finpro\projects\project-test\project-test\main.cpp 15 1 project-test Warning 11 warning C4505: 'g_bit_nth_lsf' : unreferenced local function has been removed c:\users\ian\skydrive\documents\uni\finpro\gtk\include\glib-2.0\glib\gutils.h 267 1 project-test Warning 12 warning C4505: 'g_bit_nth_msf' : unreferenced local function has been removed c:\users\ian\skydrive\documents\uni\finpro\gtk\include\glib-2.0\glib\gutils.h 269 1 project-test Warning 13 warning C4505: 'g_bit_storage' : unreferenced local function has been removed c:\users\ian\skydrive\documents\uni\finpro\gtk\include\glib-2.0\glib\gutils.h 271 1 project-test Warning 14 warning C4505: 'g_string_append_c_inline' : unreferenced local function has been removed c:\users\ian\skydrive\documents\uni\finpro\gtk\include\glib-2.0\glib\gstring.h 130 1 project-test Warning 15 warning C4505: 'g_trash_stack_push' : unreferenced local function has been removed c:\users\ian\skydrive\documents\uni\finpro\gtk\include\glib-2.0\glib\gtrashstack.h 44 1 project-test Warning 16 warning C4505: 'g_trash_stack_pop' : unreferenced local function has been removed c:\users\ian\skydrive\documents\uni\finpro\gtk\include\glib-2.0\glib\gtrashstack.h 46 1 project-test Warning 17 warning C4505: 'g_trash_stack_peek' : unreferenced local function has been removed c:\users\ian\skydrive\documents\uni\finpro\gtk\include\glib-2.0\glib\gtrashstack.h 47 1 project-test Warning 18 warning C4505: 'g_trash_stack_height' : unreferenced local function has been removed c:\users\ian\skydrive\documents\uni\finpro\gtk\include\glib-2.0\glib\gtrashstack.h 48 1 project-test Error 19 error LNK2005: "long __cdecl abs(long)" (?abs@@YAJJ@Z) already defined in FitsFile.obj C:\Users\Ian\SkyDrive\Documents\Uni\FINPRO\projects\project-test\project-test\main.obj project-test Error 20 error LNK2005: "__int64 __cdecl abs(__int64)" (?abs@@YA_J_J@Z) already defined in FitsFile.obj C:\Users\Ian\SkyDrive\Documents\Uni\FINPRO\projects\project-test\project-test\main.obj project-test Error 21 error LNK2005: "struct _ldiv_t __cdecl div(long,long)" (?div@@YA?AU_ldiv_t@@JJ@Z) already defined in FitsFile.obj C:\Users\Ian\SkyDrive\Documents\Uni\FINPRO\projects\project-test\project-test\main.obj project-test Error 22 error LNK2005: "struct _lldiv_t __cdecl div(__int64,__int64)" (?div@@YA?AU_lldiv_t@@_J0@Z) already defined in FitsFile.obj C:\Users\Ian\SkyDrive\Documents\Uni\FINPRO\projects\project-test\project-test\main.obj project-test Error 23 error LNK2005: _getwchar already defined in FitsFile.obj C:\Users\Ian\SkyDrive\Documents\Uni\FINPRO\projects\project-test\project-test\main.obj project-test Error 24 error LNK2005: _putwchar already defined in FitsFile.obj C:\Users\Ian\SkyDrive\Documents\Uni\FINPRO\projects\project-test\project-test\main.obj project-test Error 25 error LNK1169: one or more multiply defined symbols found C:\Users\Ian\SkyDrive\Documents\Uni\FINPRO\projects\project-test\Debug\project-test.exe project-test </code></pre> <p><img src="https://i.stack.imgur.com/HC1es.png" alt="output on warning level 4"></p> <pre><code>Output for building on Warning Level 4 (when only including for one place) Warning 1 warning C4273: 'getwchar' : inconsistent dll linkage c:\program files (x86)\microsoft visual studio 11.0\vc\include\stdio.h 615 1 project-test Warning 2 warning C4273: 'putwchar' : inconsistent dll linkage c:\program files (x86)\microsoft visual studio 11.0\vc\include\stdio.h 617 1 project-test Warning 3 warning C4100: 'data' : unreferenced formal parameter c:\users\ian\skydrive\documents\uni\finpro\projects\project-test\project-test\main.cpp 8 1 project-test Warning 4 warning C4100: 'event' : unreferenced formal parameter c:\users\ian\skydrive\documents\uni\finpro\projects\project-test\project-test\main.cpp 8 1 project-test Warning 5 warning C4100: 'widget' : unreferenced formal parameter c:\users\ian\skydrive\documents\uni\finpro\projects\project-test\project-test\main.cpp 8 1 project-test Warning 6 warning C4100: 'data' : unreferenced formal parameter c:\users\ian\skydrive\documents\uni\finpro\projects\project-test\project-test\main.cpp 15 1 project-test Warning 7 warning C4100: 'event' : unreferenced formal parameter c:\users\ian\skydrive\documents\uni\finpro\projects\project-test\project-test\main.cpp 15 1 project-test Warning 8 warning C4100: 'widget' : unreferenced formal parameter c:\users\ian\skydrive\documents\uni\finpro\projects\project-test\project-test\main.cpp 15 1 project-test Warning 9 warning C4505: 'g_bit_nth_lsf' : unreferenced local function has been removed c:\users\ian\skydrive\documents\uni\finpro\gtk\include\glib-2.0\glib\gutils.h 267 1 project-test Warning 10 warning C4505: 'g_bit_nth_msf' : unreferenced local function has been removed c:\users\ian\skydrive\documents\uni\finpro\gtk\include\glib-2.0\glib\gutils.h 269 1 project-test Warning 11 warning C4505: 'g_bit_storage' : unreferenced local function has been removed c:\users\ian\skydrive\documents\uni\finpro\gtk\include\glib-2.0\glib\gutils.h 271 1 project-test Warning 12 warning C4505: 'g_string_append_c_inline' : unreferenced local function has been removed c:\users\ian\skydrive\documents\uni\finpro\gtk\include\glib-2.0\glib\gstring.h 130 1 project-test Warning 13 warning C4505: 'g_trash_stack_push' : unreferenced local function has been removed c:\users\ian\skydrive\documents\uni\finpro\gtk\include\glib-2.0\glib\gtrashstack.h 44 1 project-test Warning 14 warning C4505: 'g_trash_stack_pop' : unreferenced local function has been removed c:\users\ian\skydrive\documents\uni\finpro\gtk\include\glib-2.0\glib\gtrashstack.h 46 1 project-test Warning 15 warning C4505: 'g_trash_stack_peek' : unreferenced local function has been removed c:\users\ian\skydrive\documents\uni\finpro\gtk\include\glib-2.0\glib\gtrashstack.h 47 1 project-test Warning 16 warning C4505: 'g_trash_stack_height' : unreferenced local function has been removed c:\users\ian\skydrive\documents\uni\finpro\gtk\include\glib-2.0\glib\gtrashstack.h 48 1 project-test </code></pre> <p><img src="https://i.stack.imgur.com/3vZkm.png" alt="enter image description here"></p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USIan Cant
    1. USIan Cant
    plurals
    1. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POHow to include a file only once / Prevent Function Redefinitions in old C API from C++ Program
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POHow to include a file only once / Prevent Function Redefinitions in old C API from C++ Program
      1. This table or related slice is empty.
      1. VTDownMod
    1. COIt sounds like this C "API" is not very API-like if you have this much trouble with using. Are there detailed instructions or anything on usage?
      singulars
      1. POHow to include a file only once / Prevent Function Redefinitions in old C API from C++ Program
      1. UScrashmstr
    2. COtypedefs are only a problem if the file is included twice for the same object file. redefintion in the linker phase is due to definition of variables - so you need to provide more info on the header and the exact errors
      singulars
      1. POHow to include a file only once / Prevent Function Redefinitions in old C API from C++ Program
      1. USMark
    3. COCan you clarify if the linker is complaining about duplicate functions or duplicate variables?
      singulars
      1. POHow to include a file only once / Prevent Function Redefinitions in old C API from C++ Program
      1. USWill Dean
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload