Compiling C++ code with cygwin for JNI (Android NDK)

Question

I'm trying to build a C++ file for using in my Android application over JNI. I'm building in Windows using Cygwin. I'm completely new to this and don't know what I am doing.

Here's part of the output:

$ g++ -c test_wrap.cxx -I"C:\dev\android-ndk-r4b\build\platforms\android-4\arch-arm\usr\include" -I./include
In file included from C:/dev/android-ndk-r4b/build/platforms/android-4/arch-arm/usr/include/sys/_types.h:40,
                 from C:/dev/android-ndk-r4b/build/platforms/android-4/arch-arm/usr/include/stdint.h:32,
                 from C:/dev/android-ndk-r4b/build/platforms/android-4/arch-arm/usr/include/sys/types.h:34,
                 from C:/dev/android-ndk-r4b/build/platforms/android-4/arch-arm/usr/include/strings.h:42,
                 from C:/dev/android-ndk-r4b/build/platforms/android-4/arch-arm/usr/include/stdlib.h:42,
                 from test_wrap.cxx:160:
C:/dev/android-ndk-r4b/build/platforms/android-4/arch-arm/usr/include/machine/_types.h:44: error: conflicting declaration 'typedef long unsigned int size_t'/usr/lib/gcc/i686-pc-cygwin/3.4.4/include/stddef.h:213: error: 'size_t' has a previous declaration as `typedef unsigned int size_t'
C:/dev/android-ndk-r4b/build/platforms/android-4/arch-arm/usr/include/machine/_types.h:44: error: declaration of `typedef long unsigned int size_t'/usr/lib/gcc/i686-pc-cygwin/3.4.4/include/stddef.h:213: error: conflicts with previous declaration `typedef unsigned int size_t'
C:/dev/android-ndk-r4b/build/platforms/android-4/arch-arm/usr/include/machine/_types.h:44: error: declaration of `typedef long unsigned int size_t'/usr/lib/gcc/i686-pc-cygwin/3.4.4/include/stddef.h:213: error: conflicts with previous declaration `typedef unsigned int size_t'
C:/dev/android-ndk-r4b/build/platforms/android-4/arch-arm/usr/include/machine/_types.h:46: error: conflicting declaration 'typedef long int ptrdiff_t'/usr/lib/gcc/i686-pc-cygwin/3.4.4/include/stddef.h:151: error: 'ptrdiff_t' has a previous declaration as `typedef int ptrdiff_t'
C:/dev/android-ndk-r4b/build/platforms/android-4/arch-arm/usr/include/machine/_types.h:46: error: declaration of `typedef long int ptrdiff_t'/usr/lib/gcc/i686-pc-cygwin/3.4.4/include/stddef.h:151: error: conflicts with previous declaration `typedef int ptrdiff_t'
C:/dev/android-ndk-r4b/build/platforms/android-4/arch-arm/usr/include/machine/_types.h:46: error: declaration of `typedef long int ptrdiff_t'/usr/lib/gcc/i686-pc-cygwin/3.4.4/include/stddef.h:151: error: conflicts with previous declaration `typedef int ptrdiff_t'

Can you please give me a hand?

Emmanuel

Answer 1

Applications built in the Cygwin environment assume that the application will execute on Windows with the Cygwin DLL available. As yock stated, you need to set up a cross-compiler targeted for the Android operating system.

Answer 2

I'm not a C/C++ expert at all, but it seems to me that you're trying to compile for Arm with a compiler targeting i686. Just including the header files you want isn't enough to tell GCC to target an arch, you need a cross compiler.

http://wiki.osdev.org/GCC_Cross-Compiler

Answer 3

What you're trying to do with cygwin will not work for the reasons stated in David Harrris' answer.

You can get the (correct) cross compiler that runs in Windows here . There is also a C/C++ compiler included in the Android NDK, which you can find here

Answer 4

You should use androis gcc version to compile your source. Using ndk-build and the NDK build tools.

If you just want to get rid of the 'already defined' error undefine it first to make sure your version is getting used:

#undef size_t
#undef ptrdiff_t

Answer 5

答案很简单，就是创建一个Android.mk文件并使用ndk-build命令。