C# 字符串指针参数
许明吉博客 人气:0最近用c#写一个小软件,要调用VC写的dll,传递参数给dll,由于是非托管代码,所以调用起来有点麻烦,要把参数转换成非托管代码的指针参数,然后再传递给dllview plaincopy to clipboardprint?
using System.Runtime.InteropServices; //操作Dll的类空间 class CGicomIndex { [DllImport("Index_dll.dll")] unsafe private static extern Int32 create_index_file(IntPtr filename, IntPtr fieldname, UInt32 tongshu, IntPtr err); //VC原型 create_index_file( char*filename, char * fieldname, unsigned long tongshu, char *err); #region " bool CreateIndexFile( string m_strFileName, string m_strFieldName, UInt32 m_key, ref string strErr ) 对DBF文件按照指定的字段创建索引" /// <summary> /// 对DBF文件按照指定的字段创建索引 /// </summary> /// <param name="m_strFileName">DBF文件路径</param> /// <param name="m_strFieldName">创建索引的字段名称</param> /// <param name="m_key">索引桶数(文件记录的最大数)</param> /// <param name="strErr">出错信息</param> /// <returns>成功 true</returns> public static bool CreateIndexFile( string m_strFileName, string m_strFieldName, UInt32 m_key, ref string strErr ) { try { IntPtr ptrFileName, ptrFieldName, ptrErr; //根据数据的长度申请非托管空间 ptrFileName = mallocIntptr(m_strFileName); ptrFieldName = mallocIntptr(m_strFieldName); ptrErr = mallocIntptr(300); //创建索引 if (create_index_file(ptrFileName, ptrFieldName, m_key, ptrErr) != 1) { strErr = Marshal.PtrToStringAnsi(ptrErr); Marshal.FreeHGlobal(ptrFileName); Marshal.FreeHGlobal(ptrFieldName); Marshal.FreeHGlobal(ptrErr); return false; } Marshal.FreeHGlobal(ptrFileName); Marshal.FreeHGlobal(ptrFieldName); Marshal.FreeHGlobal(ptrErr); return true; } catch (System.Exception ex) { strErr = ex.Message; return false; } } #endregion #region " IntPtr mallocIntptr( string strData ) 根据数据的长度申请非托管空间" /// <summary> /// 根据数据的长度申请非托管空间 /// </summary> /// <param name="strData">要申请非托管空间的数据</param> /// <returns>指向非拖管空间的指针</returns> private static IntPtr mallocIntptr( string strData ) { //先将字符串转化成字节方式 Byte[] btData = System.Text.Encoding.Default.GetBytes(strData); //申请非拖管空间 IntPtr m_ptr = Marshal.AllocHGlobal(btData.Length); //给非拖管空间清0 Byte[] btZero = new Byte[btData .Length+ 1]; //一定要加1,否则后面是乱码,原因未找到 Marshal.Copy(btZero, 0, m_ptr, btZero.Length); //给指针指向的空间赋值 Marshal.Copy(btData, 0, m_ptr, btData.Length); return m_ptr; } /// <summary> /// 根据长度申请非托管空间 /// </summary> /// <param name="strData">要申请非托管空间的大小</param> /// <returns>指向非拖管空间的指针</returns> private static IntPtr mallocIntptr( int length ) { //申请非拖管空间 IntPtr m_ptr = Marshal.AllocHGlobal(length); //给非拖管空间清0 Byte[] btZero = new Byte[length + 1]; //一定要加1,否则后面是乱码,原因未找到 Marshal.Copy(btZero, 0, m_ptr, btZero.Length); //给指针指向的空间赋值 Marshal.Copy(btZero, 0, m_ptr, length); return m_ptr; } #endregion }
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