c# dllimport 调用函数，参数乱码

[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
private static extern bool WritePrivateProfileString(string lpAppName, string lpKeyName, string lpString, string lpFileName);

原因是没有设置CharSet = CharSet.Auto这个属性