Error Undefined Symbol
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After all of the input files have been read and all symbol resolution is complete, the link-editor searches the internal symbol table for any symbol references that have not been bound to symbol definitions. These symbol references are referred to as undefined symbols. Undefined symbols can affect undefined symbol math the link-edit process according to the type of symbol, together with the type of output file undefined symbol c++ being generated. Generating an Executable Output File When generating an executable output file, the link-editor's default behavior is to terminate with an appropriate undefined symbol in c error message should any symbols remain undefined. A symbol remains undefined when a symbol reference in a relocatable object is never matched to a symbol definition. $ cat main.c extern int foo(); int main() { return (foo()); }
Undefined Symbol C++ Runtime
$ cc -o prog main.c Undefined first referenced symbol in file foo main.o ld: fatal: Symbol referencing errors. No output written to prog Similarly, if a shared object is used to create a dynamic executable and leaves an unresolved symbol definition, an undefined symbol error results. $ cat foo.c extern int bar; int foo() { return (bar); } $ cc -o libfoo.so -G -K pic foo.c $ cc -o prog main.c -L. -lfoo Undefined first referenced undefined symbol linux symbol in file bar ./libfoo.so ld: fatal: Symbol referencing errors. No output written to prog To allow undefined symbols, as in the previous example, use the link-editor's -z nodefs option to suppress the default error condition. Note – Take care when using the -z nodefs option. If an unavailable symbol reference is required during the execution of a process, a fatal runtime relocation error occurs. This error might be detected during the initial execution and testing of an application. However, more complex execution paths can result in this error condition taking much longer to detect, which can be time consuming and costly. Symbols can also remain undefined when a symbol reference in a relocatable object is bound to a symbol definition in an implicitly defined shared object. For example, continuing with the files main.c and foo.c used in the previous example. $ cat bar.c int bar = 1; $ cc -o libbar.so -R. -G -K pic bar.c -L. -lfoo $ ldd libbar.so libfoo.so => ./libfoo.so $ cc -o prog main.c -L. -lbar Undefined first referenced symbol in file foo main.o (symbol belongs to implicit \ dependency ./libfoo.so) ld: fatal: Symbol referencing errors. No output written to prog prog is built with an explicit reference to libbar.so. libbar.so has a dependency on libfoo.so. Therefore, an implicit reference to libfoo.so from prog is established. Because main.c made a specific
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Undefined Symbol Error In Turbo C
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Linker Error Undefined Symbol In Module
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a Static Library Primary Software: LabWindows/CVI Development Systems>>LabWindows/CVI Full Development System Primary Software Version: 2009 SP1 Primary Software Fixed Version: N/A Secondary Software: N/A Problem: I'm developing http://digital.ni.com/public.nsf/allkb/BF8084DB74021EE986257AB200001737 a DLL in LabWindows/CVI 2012. After creating a Dynamic Link Library project in Debug configuration, I set the Build»Target Type to Static Library. When I try to build my project after changing the Target Type, LabWindows/CVI throws several link errors: Undefined symbol'__CompiledDebuggingLevel' referenced in "C:\Program Files\National Instruments\CVI2012\bin\msvc\cvistart.lib". How can I resolve these errors? Solution: The link error occurs because you switched undefined symbol the project's Target Type from being a Dynamic Link Library in Debug configuration to being a Static Library. Static libraries cannot be built in a Debug configuration, so LabWindows/CVI tries to change the configuration to Release. However, this change creates an inconsistent configuration state, which causes the Static Library to build with Debug symbols that it does not define. You error undefined symbol can fix this erroneous configuration state by reselecting Release as the Target Configuration. Click Build»Configuration»Release (see Figure 2). The Release option will already be checked, but you should select it anyway. Reselecting Release will create a stable configuration, and your project will build without the Debug symbols. Note: This error, reported as Known Issue 372694, has been fixed as of LabWindows/CVI 2012 SP1. See LabWindows™/CVI™ 2012 SP1 Bug Fix Information for more details. For other possible causes of link errors with undefined symbols, see the related links below. Related Links: White Paper: LabWindows™/CVI™ 2012 SP1 Bug Fix Information White Paper: LabWindows™/CVI™ Known Issues KnowledgeBase 6CB982QW: Why Do I Receive Undefined Symbol Errors When Building a LabWindows/CVI Project that Uses GPIB/GPIB 488.2 or VXI Libraries? KnowledgeBase 3W9DPTG2: Syntax Error or Link Error When Calling a DLL in LabWindows/CVI KnowledgeBase 24BDGI1B: Why Do I Get an 'Undefined Symbol' Error When I Try To Build a Project in CVI Using Code Interface Node (CIN) Memory Manager Functions? KnowledgeBase 3MKIDTMY: Why Do I Get "undefined symbol" Errors With DAQmx Base C Examples in LabWindows™/CVI