OS X El Capitan 10.11.2， CGAL库通过macports（版本2.3.4）。
我有一个文件（/Users/Arseniy/Desktop/vec.cpp）：
#include <iostream>
#include <CGAL/Simple_cartesian.h>
typedef CGAL::Simple_cartesian<double> Kernel;
typedef Kernel::Point_2 Point_2;
typedef Kernel::Segment_2 Segment_2;
int main ()
{
double x,y;
std::cin >> x >> y;
Point_2 p(x,y);
std::cout << " p = (" << p.x() << ", " << p.y() << ")";
}
尝试编译它：
g++ -o point point.cpp -I /opt/local/include/ -L /opt/local/lib
它返回：
Apple LLVM version 7.0.0 (clang-700.1.76)
Target: x86_64-apple-darwin15.2.0
Thread model: posix
"/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang" -cc1 -triple x86_64-apple-macosx10.11.0 -Wdeprecated-objc-isa-usage -Werror=deprecated-objc-isa-usage -emit-obj -mrelax-all -disable-free -disable-llvm-verifier -main-file-name point.cpp -mrelocation-model pic -pic-level 2 -mthread-model posix -mdisable-fp-elim -masm-verbose -munwind-tables -target-cpu core2 -target-linker-version 253.6 -v -dwarf-column-info -resource-dir /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/clang/7.0.0 -I /opt/local/include -stdlib=libc++ -fdeprecated-macro -fdebug-compilation-dir /opt/local/include/CGAL -ferror-limit 19 -fmessage-length 81 -stack-protector 1 -mstackrealign -fblocks -fobjc-runtime=macosx-10.11.0 -fencode-extended-block-signature -fcxx-exceptions -fexceptions -fmax-type-align=16 -fdiagnostics-show-option -fcolor-diagnostics -o /var/folders/70/rkkp65gs58jg_wlfvjkw89v80000gn/T/point-4355d9.o -x c++ point.cpp
clang -cc1 version 7.0.0 based upon LLVM 3.7.0svn default target x86_64-apple-darwin15.2.0
ignoring nonexistent directory "/usr/include/c++/v1"
ignoring nonexistent directory "/usr/local/include"
#include "..." search starts here:
#include <...> search starts here:
/opt/local/include
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/clang/7.0.0/include
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include
/usr/include
/System/Library/Frameworks (framework directory)
/Library/Frameworks (framework directory)
End of search list.
"/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld" -demangle -dynamic -arch x86_64 -macosx_version_min 10.11.0 -o point -L/opt/local/lib /var/folders/70/rkkp65gs58jg_wlfvjkw89v80000gn/T/point-4355d9.o -lc++ -lSystem /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/clang/7.0.0/lib/darwin/libclang_rt.osx.a
Undefined symbols for architecture x86_64:
"CGAL::assertion_fail(char const*, char const*, int, char const*)", referenced from:
CGAL::Interval_nt<false>::Test_runtime_rounding_modes::Test_runtime_rounding_modes() in point-4355d9.o
CGAL::Interval_nt<true>::Test_runtime_rounding_modes::Test_runtime_rounding_modes() in point-4355d9.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
-L和-l（低和大写）之间是否存在差异？