如何判断当前节点是根结点？

[wang_bluebird]

？

[jdzwq]

GetParentItem(hCurItem) == NULL

[wang_bluebird]

MS Excel是众所周知的电子表格处理软件。Excel文件格式是特定的BIFF(Binary Interchange File Format)，BIFF里存储了很多记录，第条记录包括记录头和记录体。记录头是4byte，前两位指定记录类型的代码（opcode），后两位指定记录长度；记录体是存储该记录的实际数据。
比如：

BOF record
| Record Header | Record Body |
Byte | 0 1 2 3 | 0 1 2 3 |
-----------------------------------------
Contents | 09 | 00 | 04 | 00 | 02 | 00 | 10 | 00 |
-----------------------------------------
| opcode | length | version | file |
| | | number | type |
记录头：
opcode: 09h is BOF;
length: 04h record body is 4 bytes long;
记录体：
version number:02h is version number (2 for the initial version of Excel)
file type:10h is a worksheet file;
具体可参考MS Excel File Format。

描述
以下是对本文程序简单描述。

第一步：打开文件
CFile f;
CFileException e;

// 打开文件
if (!f.Open("D:\\Book1.xls", CFile::modeRead, &e))
{
TCHAR szError[1024];
e.GetErrorMessage(szError, 1024);
AfxMessageBox(szError);
return;
}
第二步：读取版本号
// 读取版本
while (dwPos < dwLen)
{
nRead = f.Read((void*)&RecNo, 2);
if (RecNo == XL_BOF)
{
WORD Ver, Type;
f.Read((void*)&RecLen, 2);
f.Read((void*)&Ver, 2);
f.Read((void*)&Type, 2);
f.Seek(RecLen, CFile::current);

int ver = 0;
switch (Ver)
{
case BIFF7:
ver = 7;
break;
case BIFF8:
ver = 8;
AfxMessageBox("Biff8");
break;
}

int type = 0;
switch (Type)
{
case WORKBOOK:
type = 5;
AfxMessageBox("Workbook");
break;
case WORKSHEET:
type = 16;
AfxMessageBox("Worksheet");
break;
case CHART:
type = 32;
AfxMessageBox("Chart");
break;
}

break;
}
dwPos = f.GetPosition();
}
第三步：读其它数据
f.SeekToBegin();
dwPos = f.GetPosition();
// 读表格数据
while (dwPos < dwLen)
{
nRead = f.Read((void*)&RecNo, 2);
switch (RecNo)
{
case XL_BOF:
{
f.Read((void*)&RecLen, 2);
AfxMessageBox("Bof");
}
break;
case XL_BOUNDSHEET:
{
DWORD temp;
BYTE visi;
BYTE type;
TCHAR name;

f.Read((void*)&RecLen, 2);
f.Read((void*)&temp, 4);
f.Read((void*)&visi, 1);
f.Read((void*)&type, 1);
f.Read((void*)&StrLen, 2);
f.Read((void*)&name, StrLen);

char buf[128];
memset(buf, 0x0, 128);
strncpy(buf, &name, StrLen);

AfxMessageBox(buf);
}
break;
case XL_DIMENSION:
f.Read((void*)&RecLen, 2);
f.Seek(RecLen, CFile::current);
AfxMessageBox("Dimension");
break;
case 0xE2: // INTERFACED
f.Read((void*)&RecLen, 2);
AfxMessageBox("e2");
break;
case XL_SST:
f.Read((void*)&RecLen, 2);
f.Seek(RecLen, CFile::current);
AfxMessageBox("SST");
break;
case XL_NUMBER:
f.Read((void*)&RecLen, 2);
AfxMessageBox("Number");
break;
case XL_STRING:
f.Read((void*)&RecLen, 2);
AfxMessageBox("String");
break;
case XL_RK:
f.Read((void*)&RecLen, 2);
AfxMessageBox("RK");
break;
case XL_LABEL:
{
f.Read((void*)&RecLen, 2);
AfxMessageBox("Label");
}
break;
case 0xD6:
f.Read((void*)&RecLen, 2);
AfxMessageBox("RString");
break;
case XL_EOF:
dwPos = dwLen;
AfxMessageBox("Eof");
break;
default:
nRead = f.Read((void*)&RecLen, 2);
if (nRead == 0)
dwPos = dwLen;
break;
}
}
第四步：关闭文件
f.Close();