關(guān)于VC網(wǎng)絡(luò)編程中用 char 發(fā)送結(jié)構(gòu)體的說(shuō)明
??? 在VC中要發(fā)送struct的程序，如果需要中間打包的話，首先因該將結(jié)構(gòu)體轉(zhuǎn)換為字節(jié)型的。然后再用
send (SOCKET s,const char FAR * buf,int len,int flags)發(fā)送。
這里要注意的是buf可以包含\0字符，而且len必須正確。
包含有\(zhòng)0字符的struct中間過程轉(zhuǎn)換成char可能會(huì)有問題。
這里是一個(gè)字符轉(zhuǎn)換的CLASS

// Buffer.cpp: implementation of the CBuffer class.
//
//

#include "stdafx.h"
#include "Buffer.h"
#include "Math.h"

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif



//
// Construction/Destruction
//


//
// FUNCTION:??? CBuffer
//
// DESCRIPTION:??? Constructs the buffer with a default size
//
// RETURNS:????? ?
//
// NOTES:? ?
//
// MODIFICATIONS:
//
// Name??????????????? Date??????? Version??????? Comments
// N T ALMOND?????? 270400??????? 1.0??????????? Origin
//

CBuffer::CBuffer()
{
??? // Initial size
??? m_nSize = 0;

??? m_pPtr = m_pBase = NULL;
}


//
// FUNCTION:??? ~CBuffer
//
// DESCRIPTION:??? Deallocates the buffer
//
// RETURNS:????? ?
//
// NOTES:? ?
//
// MODIFICATIONS:
//
// Name??????????????? Date??????? Version??????? Comments
// N T ALMOND?????? 270400??????? 1.0??????????? Origin
//

CBuffer::~CBuffer()
{
??? if (m_pBase)
??????? VirtualFree(m_pBase,0,MEM_RELEASE);
}
? ?


//
// FUNCTION:??? Write
//
// DESCRIPTION:??? Writes data into the buffer
//
// RETURNS:????? ?
//
// NOTES:? ?
//
// MODIFICATIONS:
//
// Name??????????????? Date??????? Version??????? Comments
// N T ALMOND?????? 270400??????? 1.0??????????? Origin
//

BOOL CBuffer::Write(PBYTE pData, UINT nSize)
{
??? ReAllocateBuffer(nSize + GetBufferLen());

??? CopyMemory(m_pPtr,pData,nSize);

??? // Advance Pointer
??? m_pPtr+=nSize;

??? return nSize;
}


//
// FUNCTION:??? Insert
//
// DESCRIPTION:??? Insert data into the buffer
//
// RETURNS:????? ?
//
// NOTES:? ?
//
// MODIFICATIONS:
//
// Name??????????????? Date??????? Version??????? Comments
// N T ALMOND?????? 270400??????? 1.0??????????? Origin
//

BOOL CBuffer::Insert(PBYTE pData, UINT nSize)
{
??? ReAllocateBuffer(nSize + GetBufferLen());

??? MoveMemory(m_pBase+nSize,m_pBase,GetMemSize() - nSize);
??? CopyMemory(m_pBase,pData,nSize);

??? // Advance Pointer
??? m_pPtr+=nSize;

??? return nSize;
}



//
// FUNCTION:??? Read
//
// DESCRIPTION:??? Reads data from the buffer and deletes what it reads
//
// RETURNS:????? ?
//
// NOTES:? ?
//
// MODIFICATIONS:
//
// Name??????????????? Date??????? Version??????? Comments
// N T ALMOND?????? 270400??????? 1.0??????????? Origin
//

UINT CBuffer::Read(PBYTE pData, UINT nSize)
{
??? // Trying to byte off more than ya can chew - eh?
??? if (nSize > GetMemSize())
??????? return 0;

??? // all that we have
??? if (nSize > GetBufferLen())
??????? nSize = GetBufferLen();

????? ?
??? if (nSize)
??? {
??????? // Copy over required amount and its not up to us
??????? // to terminate the buffer - got that!!!
??????? CopyMemory(pData,m_pBase,nSize);
????? ?
??????? // Slide the buffer back - like sinking the data
??????? MoveMemory(m_pBase,m_pBase+nSize,GetMemSize() - nSize);

??????? m_pPtr -= nSize;
??? }
????? ?
??? DeAllocateBuffer(GetBufferLen());

??? return nSize;
}


//
// FUNCTION:??? GetMemSize
//
// DESCRIPTION:??? Returns the phyical memory allocated to the buffer
//
// RETURNS:????? ?
//
// NOTES:? ?
//
// MODIFICATIONS:
//
// Name??????????????? Date??????? Version??????? Comments
// N T ALMOND?????? 270400??????? 1.0??????????? Origin
//

UINT CBuffer::GetMemSize()
{
??? return m_nSize;
}


//
// FUNCTION:??? GetBufferLen
//
// DESCRIPTION:??? Get the buffer 'data' length
//
// RETURNS:????? ?
//
// NOTES:? ?
//
// MODIFICATIONS:
//
// Name??????????????? Date??????? Version??????? Comments
// N T ALMOND?????? 270400??????? 1.0??????????? Origin
//

UINT CBuffer::GetBufferLen()
{
??? if (m_pBase == NULL)
??????? return 0;

??? int nSize =
??????? m_pPtr - m_pBase;
??? return nSize;
}


//
// FUNCTION:??? ReAllocateBuffer
//
// DESCRIPTION:??? ReAllocateBuffer the Buffer to the requested size
//
// RETURNS:????? ?
//
// NOTES:? ?
//
// MODIFICATIONS:
//
// Name??????????????? Date??????? Version??????? Comments
// N T ALMOND?????? 270400??????? 1.0??????????? Origin
//

UINT CBuffer::ReAllocateBuffer(UINT nRequestedSize)
{
??? if (nRequestedSize < GetMemSize())
??????? return 0;

??? // Allocate new size
??? UINT nNewSize = (UINT) ceil(nRequestedSize / 1024.0) * 1024;

??? // New Copy Data Over
??? PBYTE pNewBuffer = (PBYTE) VirtualAlloc(NULL,nNewSize,MEM_COMMIT,PAGE_READWRITE);

??? UINT nBufferLen = GetBufferLen();
??? CopyMemory(pNewBuffer,m_pBase,nBufferLen);

??? if (m_pBase)
??????? VirtualFree(m_pBase,0,MEM_RELEASE);


??? // Hand over the pointer
??? m_pBase = pNewBuffer;

??? // Realign position pointer
??? m_pPtr = m_pBase + nBufferLen;

??? m_nSize = nNewSize;

??? return m_nSize;
}


//
// FUNCTION:??? DeAllocateBuffer
//
// DESCRIPTION:??? DeAllocates the Buffer to the requested size
//
// RETURNS:????? ?
//
// NOTES:? ?
//
// MODIFICATIONS:
//
// Name??????????????? Date??????? Version??????? Comments
// N T ALMOND?????? 270400??????? 1.0??????????? Origin
//

UINT CBuffer::DeAllocateBuffer(UINT nRequestedSize)
{
??? if (nRequestedSize < GetBufferLen())
??????? return 0;

??? // Allocate new size
??? UINT nNewSize = (UINT) ceil(nRequestedSize / 1024.0) * 1024;

??? if (nNewSize < GetMemSize())
??????? return 0;

??? // New Copy Data Over
??? PBYTE pNewBuffer = (PBYTE) VirtualAlloc(NULL,nNewSize,MEM_COMMIT,PAGE_READWRITE);

??? UINT nBufferLen = GetBufferLen();
??? CopyMemory(pNewBuffer,m_pBase,nBufferLen);

??? VirtualFree(m_pBase,0,MEM_RELEASE);

??? // Hand over the pointer
??? m_pBase = pNewBuffer;

??? // Realign position pointer
??? m_pPtr = m_pBase + nBufferLen;

??? m_nSize = nNewSize;

??? return m_nSize;
}


//
// FUNCTION:??? Scan
//
// DESCRIPTION:??? Scans the buffer for a given byte sequence
//
// RETURNS:??????? Logical offset
//
// NOTES:? ?
//
// MODIFICATIONS:
//
// Name??????????????? Date??????? Version??????? Comments
// N T ALMOND?????? 270400??????? 1.0??????????? Origin
//

int CBuffer::Scan(PBYTE pScan,UINT nPos)
{
??? if (nPos > GetBufferLen() )
??????? return -1;

??? PBYTE pStr = (PBYTE) strstr((char*)(m_pBase+nPos),(char*)pScan);
? ?
??? int nOffset = 0;

??? if (pStr)
??????? nOffset = (pStr - m_pBase) + strlen((char*)pScan);

??? return nOffset;
}


//
// FUNCTION:??? ClearBuffer
//
// DESCRIPTION:??? Clears/Resets the buffer
//
// RETURNS:? ?
//
// NOTES:? ?
//
// MODIFICATIONS:
//
// Name??????????????? Date??????? Version??????? Comments
// N T ALMOND?????? 270400??????? 1.0??????????? Origin
//

void CBuffer::ClearBuffer()
{
??? // Force the buffer to be empty
??? m_pPtr = m_pBase;

??? DeAllocateBuffer(1024);
}


//
// FUNCTION:??? Write
//
// DESCRIPTION:??? Writes a string a the end of the buffer
//
// RETURNS:? ?
//
// NOTES:? ?
//
// MODIFICATIONS:
//
// Name??????????????? Date??????? Version??????? Comments
// N T ALMOND?????? 270400??????? 1.0??????????? Origin
//

BOOL CBuffer::Write(CString& strData)
{
??? int nSize = strData.GetLength();
??? return Write((PBYTE) strData.GetBuffer(nSize), nSize);
}


//
// FUNCTION:??? Insert
//
// DESCRIPTION:??? Insert a string at the beginning of the buffer
//
// RETURNS:? ?
//
// NOTES:? ?
//
// MODIFICATIONS:
//
// Name??????????????? Date??????? Version??????? Comments
// N T ALMOND?????? 270400??????? 1.0??????????? Origin
//

BOOL CBuffer::Insert(CString& strData)
{
??? int nSize = strData.GetLength();
??? return Insert((PBYTE) strData.GetBuffer(nSize), nSize);
}


//
// FUNCTION:??? Copy
//
// DESCRIPTION:??? Copy from one buffer object to another...
//
// RETURNS:? ?
//
// NOTES:? ?
//
// MODIFICATIONS:
//
// Name??????????????? Date??????? Version??????? Comments
// N T ALMOND?????? 270400??????? 1.0??????????? Origin
//

void CBuffer::Copy(CBuffer& buffer)
{
??? int nReSize = buffer.GetMemSize();
??? int nSize = buffer.GetBufferLen();
??? ClearBuffer();
??? ReAllocateBuffer(nReSize);

??? m_pPtr = m_pBase + nSize;

??? CopyMemory(m_pBase,buffer.GetBuffer(),buffer.GetBufferLen());
}


//
// FUNCTION:??? GetBuffer
//
// DESCRIPTION:??? Returns a pointer to the physical memory determined by the offset
//
// RETURNS:? ?
//
// NOTES:? ?
//
// MODIFICATIONS:
//
// Name??????????????? Date??????? Version??????? Comments
// N T ALMOND?????? 270400??????? 1.0??????????? Origin
//

PBYTE CBuffer::GetBuffer(UINT nPos)
{
??? return m_pBase+nPos;
}



//
// FUNCTION:??? GetBuffer
//
// DESCRIPTION:??? Returns a pointer to the physical memory determined by the offset
//
// RETURNS:? ?
//
// NOTES:? ?
//
// MODIFICATIONS:
//
// Name??????????????? Date??????? Version??????? Comments
// N T ALMOND?????? 270400??????? 1.0??????????? Origin
//
///
void CBuffer::FileWrite(const CString& strFileName)
{
??? CFile file;

??? if (file.Open(strFileName, CFile::modeWrite | CFile::modeCreate))
??? {
??????? file.Write(m_pBase,GetBufferLen());
??????? file.Close();
??? }
}




//
// FUNCTION:??? Delete
//
// DESCRIPTION:??? Delete data from the buffer and deletes what it reads
//
// RETURNS:????? ?
//
// NOTES:? ?
//
// MODIFICATIONS:
//
// Name??????????????? Date??????? Version??????? Comments
// N T ALMOND?????? 270400??????? 1.0??????????? Origin
//

UINT CBuffer::Delete(UINT nSize)
{
??? // Trying to byte off more than ya can chew - eh?
??? if (nSize > GetMemSize())
??????? return 0;

??? // all that we have
??? if (nSize > GetBufferLen())
??????? nSize = GetBufferLen();

????? ?
??? if (nSize)
??? {
??????? // Slide the buffer back - like sinking the data
??????? MoveMemory(m_pBase,m_pBase+nSize,GetMemSize() - nSize);

??????? m_pPtr -= nSize;
??? }
????? ?
??? DeAllocateBuffer(GetBufferLen());

??? return nSize;
}

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