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Berkeley DB: unable to compile C ++ codes

When I compiled the C ++ code samples I got the following information:

c++ excxx_example_database_read.cpp -o dbApp -I /usr/local/BerkeleyDB.5.0/include/
Undefined symbols:
  "Dbt::Dbt(void*, unsigned int)", referenced from:
      show_vendor(MyDb&, char const*)in ccnaWItX.o
      show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o
  "Dbc::get(Dbt*, Dbt*, unsigned int)", referenced from:
      show_all_records(MyDb&, MyDb&) in ccnaWItX.o
      show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o
      show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o
  "Dbc::close()", referenced from:
      show_all_records(MyDb&, MyDb&) in ccnaWItX.o
      show_all_records(MyDb&, MyDb&) in ccnaWItX.o
      show_all_records(MyDb&, MyDb&) in ccnaWItX.o
      show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o
      show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o
      show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o
  "Dbt::~Dbt()", referenced from:
      show_vendor(MyDb&, char const*)in ccnaWItX.o
      show_vendor(MyDb&, char const*)in ccnaWItX.o
      show_vendor(MyDb&, char const*)in ccnaWItX.o
      show_vendor(MyDb&, char const*)in ccnaWItX.o
      show_all_records(MyDb&, MyDb&) in ccnaWItX.o
      show_all_records(MyDb&, MyDb&) in ccnaWItX.o
      show_all_records(MyDb&, MyDb&) in ccnaWItX.o
      show_all_records(MyDb&, MyDb&) in ccnaWItX.o
      show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o
      show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o
      show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o
      show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o
  "Db::~Db()", referenced from:
      MyDb::~MyDb() in ccnaWItX.o
      MyDb::~MyDb() in ccnaWItX.o
  "typeinfo for DbException", referenced from:
      GCC_except_table3 in ccnaWItX.o
      GCC_except_table4 in ccnaWItX.o
      GCC_except_table5 in ccnaWItX.o
      GCC_except_table6 in ccnaWItX.o
      __ZTI11DbException$non_lazy_ptr in ccnaWItX.o
  "DbException::~DbException()", referenced from:
      __ZN11DbExceptionD1Ev$non_lazy_ptr in ccnaWItX.o
  "MyDb::close()", referenced from:
      MyDb::~MyDb() in ccnaWItX.o
  "MyDb::MyDb(std::basic_string<char, std::char_traits<char>, std::allocator<char> >&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&, bool)", referenced from:
      _main in ccnaWItX.o
      _main in ccnaWItX.o
      _main in ccnaWItX.o
  "Dbt::Dbt()", referenced from:
      show_vendor(MyDb&, char const*)in ccnaWItX.o
      show_all_records(MyDb&, MyDb&) in ccnaWItX.o
      show_all_records(MyDb&, MyDb&) in ccnaWItX.o
      show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o
  "DbException::get_errno() const", referenced from:
      show_vendor(MyDb&, char const*)in ccnaWItX.o
      show_all_records(MyDb&, MyDb&) in ccnaWItX.o
      show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o
      _main in ccnaWItX.o
  "DbException::DbException(DbException const&)", referenced from:
      show_vendor(MyDb&, char const*)in ccnaWItX.o
      show_all_records(MyDb&, MyDb&) in ccnaWItX.o
      show_item(MyDb&, MyDb&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccnaWItX.o
ld: symbol(s) not found
collect2: ld returned 1 exit status

I do not know what's the problem. Please, help!

Update: I am now using:

getting_started baxxu$ c++ excxx_example_database_r
ead.cpp -o dbApp -I /usr/local/BerkeleyDB.5.0/include/ -L/usr/local/
BerkeleyDB.5.0/lib -ldb_cxx-5.0

errors still occur:

Undefined symbols:
  "MyDb::close()", referenced from:
      MyDb::~MyDb() in ccYCyhIg.o
  "MyDb::MyDb(std::basic_string<char, std::char_traits<char>, std::allocator<char> >&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&, bool)", referenced from:
      _main in ccYCyhIg.o
      _main in ccYCyhIg.o
      _main in ccYCyhIg.o
ld: symbol(s) not found
collect2: ld returned 1 exit status
+2


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2 answers


These are linker errors - they mean that you are not linked in one or more of the libraries required to build this application.

The documentation for the library should explain how to build applications using this. In general, you need to add the library to the compiler command line:



c++ excxx_example_database_read.cpp -o dbApp -I /usr/local/BerkeleyDB.5.0/include/  -lsomething

there will be a link in libsomething.a found in the library search path. But to find out which one to link, you have to read the docs.

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You need to link with the C ++ BerkeleyDB library.

c++ excxx_example_database_read.cpp -o dbApp -I /usr/local/BerkeleyDB.5.0/include/ -L/usr/local/BerkeleyDB.5.0/lib -ldb_cxx-5.0

(I am assuming you have the library and version based on the include (-I) directive installed.)



EDIT: So it looks like you are trying to compile one of the examples included in the distribution (excxx_example_database_read.cpp) by hand ... it is more than one .cpp file. The MyDB object is not part of the BerkeleyDB API, but an example of how to subclass from it.

cd

where you have the BerkeleyDB source code, then cd build_unix

. After that domake excxx_example_database_read

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