StringBuilder和Char[]作为参数类型在平台调用中的差异如下:
- StringBuilder不能接收以2个'\0'结尾的多个字符串集合,只能保留第一个字符串,剩余的字符串被舍弃。而Char[]可以获取完整的多个字符串集合。总之,如果接收的字符串中间包含'\0',则StringBuilder只能获取第一个'\0'前的字符,后面的字符被舍弃。
- 将结果转换成String类型时,StringBuilder的转换方式为使用自身的成员函数:public overridestring ToString()。Char[]的转换方法必须使用String的构造函数:public String(Char[] value, int startIndex, int length),而不是简单的:public String(Char[] value),以消除垃圾字符。
示例一:
BOOL GetUserPreferredUILanguages( __in DWORD dwFlags, __out PULONG pulNumLanguages, __out_opt PZZWSTR pwszLanguagesBuffer, __inout PULONG pcchLanguagesBuffer );
由于pwszLanguagesBuffer中接收的是以2个'\0'结尾的多个字符串集合,因此应该使用Char[]类型。
[DllImport("Kernel32.dll", CharSet = CharSet.Auto)] private static extern Boolean GetUserPreferredUILanguages( UInt32 dwFlags, out Int32 pulNumLanguages, [Out] Char[] pwszLanguagesBuffer, ref Int32 pcchLanguagesBuffer ); /// <summary> /// 获取用户偏好的界面语言 /// </summary> /// <param name="dwFlags"> /// MUI_LANGUAGE_ID = 4:语言ID /// MUI_LANGUAGE_NAME = 8:语言名称 /// </param> /// <returns>偏好的语言集合</returns> public static String[] GetUserPreferredUILanguages(UInt32 dwFlags = MUI_LANGUAGE_NAME) { // 计算需要的空间大小 Int32 NumLanguages; Int32 cchLanguagesBuffer = 0; if (GetUserPreferredUILanguages(dwFlags, out NumLanguages, null, ref cchLanguagesBuffer)) { if (NumLanguages > 0) { // 获取实际的数据 Char[] LanguagesBuffer = new Char[cchLanguagesBuffer]; GetUserPreferredUILanguages(dwFlags, out NumLanguages, LanguagesBuffer, ref cchLanguagesBuffer); // 提取所有的语言 return new String(LanguagesBuffer).TrimEnd('\0').Split('\0'); } } return null; }
示例二:
int GetUserDefaultLocaleName( __out LPWSTR lpLocaleName, __in int cchLocaleName );
使用StringBuilder:
[DllImport("Kernel32.dll", CharSet = CharSet.Auto)] private static extern Int32 GetUserDefaultLocaleName([Out] StringBuilder lpLocaleName, Int32 cchLocaleName); public const Int32 LOCALE_NAME_MAX_LENGTH = 85; /// <summary> /// 获取用户缺省本地语言名称 /// </summary> /// <returns>本地语言名称</returns> public static String GetUserDefaultLocaleName() { StringBuilder lpLocaleName = new StringBuilder(LOCALE_NAME_MAX_LENGTH); if (GetUserDefaultLocaleName(lpLocaleName, LOCALE_NAME_MAX_LENGTH) > 0) { return lpLocaleName.ToString(); } return null; }
使用Char[],转换成String类型时需要消除垃圾字符:
[DllImport("Kernel32.dll", CharSet = CharSet.Auto)] private static extern Int32 GetUserDefaultLocaleName([Out] Char[] lpLocaleName, Int32 cchLocaleName); public const Int32 LOCALE_NAME_MAX_LENGTH = 85; /// <summary> /// 获取用户缺省本地语言名称 /// </summary> /// <returns>本地语言名称</returns> public static String GetUserDefaultLocaleName() { Char[] lpLocaleName = new Char[LOCALE_NAME_MAX_LENGTH]; Int32 Length = GetUserDefaultLocaleName(lpLocaleName, LOCALE_NAME_MAX_LENGTH); if (Length > 0) { return new String(lpLocaleName, 0, Length - 1); } return null; }