wcstombs() has invalid output on Android

问题

I'm trying to port some old C/C++ code to android(latest version of NDK), but I'm struggling with function wcstombs(). This function returns wierd result on Android and I don't know why.

Look at this code (it's wcstombs() example from C++ reference)

  const wchar_t str[] = L"wcstombs example";
  char buffer[32];
  int ret;

  ret = wcstombs ( buffer, str, sizeof(buffer) );
  if (ret==32) buffer[31]='\0';

  __android_log_print(ANDROID_LOG_WARN, "dbg", "%d ... %s", ret, buffer);


// Application.mk
APP_ABI := armeabi-v7a
APP_STL := gnustl_static
APP_PLATFORM := android-19

This code prints "2 ... w". It looks like the function stops, if it reads a zero byte from the string.

Is it normal? Is there any replacement for this function?

Thx.

回答1:

you could use

snprintf(buffer, sizeof(buffer), "%ls", str);

回答2:

I had this same issue. Changing the STL library did not work for me.

However using this implementation did work.

https://android.googlesource.com/platform/ndk/+/master/sources/android/support/src/musl-multibyte/wcsrtombs.c

There is also crystax ndk, which is a replacement for the google ndk. It could be useful.

https://www.crystax.net

回答3:

I've finally found the solution to this problem. Application has to be linked against LLVM libc++ instead of GNU STL. Application.mk should look like this:

APP_ABI := armeabi-v7a
APP_STL := c++_static
APP_PLATFORM := android-19

来源：https://stackoverflow.com/questions/25453867/wcstombs-has-invalid-output-on-android