C++ Undefined Symbol error in OSX10.7.4 - c++

Question

The following call from the command line, clang++ vcfaltcount.cpp -o vcfac, produces the following error/warnings
>In file included from vcfaltcount.cpp:1:
./Variant.h:86:5: warning: control may reach end of non-void function [-Wreturn-type]
}
>Undefined symbols for architecture x86_64:
"split(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)", referenced from:
_main in ccGOdUhH.o
vcf::VariantCallFile::open(std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccGOdUhH.o
"vcf::VariantCallFile::getNextVariant(vcf::Variant&)", referenced from:
_main in ccGOdUhH.o
"vcf::VariantCallFile::parseHeader()", referenced from:
vcf::VariantCallFile::openFile(std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)in ccGOdUhH.o
ld: symbol(s) not found for architecture x86_64
collect2: ld returned 1 exit status
There are many other posts on "undefined symbols for such&such architecture," and I have attempted to use those suggestions to successfully compile.
I think the problem may arise from the header file, variant.h. In the API from which the source code came there was a corresponding variant.cpp file that defined the functions, which were only declared in variant.h. I moved those definitions into variant.h. Any thoughts on what I may be missing? I can provide the header if need be, but it is long. Thanks.