How to detect compilation by Android NDK in a C/C++ file?

It is #ifdef __ANDROID__ as seen by running the preprocessor:

~$ /usr/local/android-ndk-r6/toolchains/arm-linux-androideabi-4.4.3/prebuilt/linux-x86/bin/arm-linux-androideabi-gcc -E -dM - < /dev/null | grep -i android

The output is:

#define __ANDROID__ 1

No need to depend on defining stuff in your project especially if you're skipping the NDK build system.

Short answer: #ifdef ANDROID .

The ANDROID macro is defined for you in build-module.mk (part of the standard build system):

# always define ANDROID when building binaries
#
LOCAL_CFLAGS := -DANDROID $(LOCAL_CFLAGS)