how to use internet(private) function in NDK

how to use internet(private) function in NDK

how to create and user internal function in ndk cpp ?
jstring Java_com_test_ndk_MainActivity_getString(JNIEnv* env, jobject thiz)
{
jstring strt = getstr();
return env->NewStringUTF(strt);
}
want to implement getstr() function over here for just use in ndk side not
java... (like on private in ndk side)