cppstudatabase.cpp

vc编写的简单的学生成绩管理系统

//////////////////////////////////////////////////////
// cppStuDataBase.cpp

#include "hStuDataBase.h"
#include <string.h>
#include <iostream.h>

/////////////////////////////////////////////
// CStuDataBase::CStuDataBase: constructor

CStuDataBase::CStuDataBase()
{
	m_RecordCount     = 0;
	m_pszDataBaseName = NULL;
	m_pfWriteFile     = NULL;
	m_pfReadFile      = NULL;
	//m_Connected     = false;
}

///////////////////////////////////////////////
//CStuDataBase::CStuDataBase: destructor

CStuDataBase::~CStuDataBase()
{
	if (m_pszDataBaseName) delete [] m_pszDataBaseName;
}

///////////////////////////////////////////////
//CStuDataBase::Connection

void CStuDataBase::Initialize(char* pszDataBaseName)
{
	if (NULL == pszDataBaseName)                    
		throw "Connection to database fail,[Invalid FileName]";

	m_pfReadFile = fopen(pszDataBaseName,"a+b");
	if (NULL == m_pfReadFile)
		throw "Connection to database fail!";

	//开始读取数据
	rewind(m_pfReadFile);          //跳到文件开头
	int iCount = 0;
	while (fread(&m_stuObject[iCount],sizeof(m_stuObject[iCount]),1,m_pfReadFile) == 1)
	{
		iCount++;  
	}
	fclose(m_pfReadFile);

	m_RecordCount = iCount;        //保存记录
	
	if (m_pszDataBaseName)
	{
		delete []m_pszDataBaseName;
		m_pszDataBaseName = NULL;
	}
    
	//以下保存文件名以便以后使用
	int iFileNameMax = strlen(pszDataBaseName);
	m_pszDataBaseName = new char[iFileNameMax + 1];
	strncpy(m_pszDataBaseName,pszDataBaseName,iFileNameMax);
	m_pszDataBaseName[iFileNameMax] = '\0';
}

/////////////////////////////////////////////////////////////////////
//CStuDataBase::AppendRecord

bool CStuDataBase::AppendRecord(CStudent* pStudent)
{
	//数据已满(CStuDatabase数的学生对像数组已满:1000个)
	if (IsFull())             
		return false;

	m_stuObject[m_RecordCount] = (*pStudent);
	m_RecordCount++;

	return true;
}

/////////////////////////////////////////////////////////////////////
//CStuDataBase::UpdateRecord

bool CStuDataBase::UpdateRecord(CStudent* pStudent,int iID)
{
	if (IsEmpty())
		return false;

	int iIndex = GetStuIndex(iID);
	if (-1 == iIndex)
		return false;
    
	//更新旧的学生对像数组的数据
	m_stuObject[iIndex] = (*pStudent);
	
	//
	//重新提交数据到数据文件
	//
	if ( PostToDataBase() )
	    return true;
	else
		return false;
}

////////////////////////////////////////////////////////////////////
//CStuDataBase::DeleteRecord

bool CStuDataBase::DeleteRecord(int iID)
{
	if (IsEmpty())
		return false;

	int iIndex = GetStuIndex(iID);
	if (-1 == iIndex)
		return false;

	for (int iCount = iIndex; iCount < m_RecordCount - 1; iCount++)
	{
		m_stuObject[iCount] = m_stuObject[iCount + 1];
	}

	if (m_RecordCount != 0)
	{
		m_pfWriteFile = fopen(m_pszDataBaseName,"wb");
		if (m_pfWriteFile == NULL)
			return false;

		int iCount = 0;
		while (iCount < m_RecordCount)
		{
			if (fwrite(&m_stuObject[iCount],sizeof(m_stuObject[iCount]),1,m_pfWriteFile))
				iCount++;
		}
		fclose(m_pfWriteFile);
	}
	--m_RecordCount;           //删除一条记录

	return true;
}

///////////////////////////////////////////////////////////////////
//CStuDataBase::DeleteRecord

bool CStuDataBase::DeleteRecord(char* pszStuName)
{
	if (IsEmpty())
		return false;

	int iIndex = GetStuIndex(pszStuName);
	if (-1 == iIndex)
		return false;

	for (int iCount = iIndex; iCount < m_RecordCount - 1; iCount++)
	{
		m_stuObject[iCount] = m_stuObject[iCount + 1];
	}

	if (m_RecordCount != 0)
	{
		m_pfWriteFile = fopen(m_pszDataBaseName,"wb");
		if (m_pfWriteFile == NULL)
			return false;

		int iCount = 0;
		while (iCount < m_RecordCount)
		{
			if (fwrite(&m_stuObject[iCount],sizeof(m_stuObject[iCount]),1,m_pfWriteFile))
				iCount++;
		}
	}
	--m_RecordCount;           //删除一条记录

	return true;
}

//////////////////////////////////////////////////////////////////////
//CStuDataBase::IsEmpty

bool CStuDataBase::IsEmpty()
{
	return (m_RecordCount == 0);
}

//////////////////////////////////////////////////////////////////////
//CStuDataBase::IsFull

bool CStuDataBase::IsFull()
{
	return (m_RecordCount >= MAX_STU);
}

/////////////////////////////////////////////////////////////////////
// CStuDataBase::FindRecord

CStudent* CStuDataBase::FindRecord(int iStuID)
{
	if (IsEmpty())
	    return NULL;

	int iIndex = GetStuIndex(iStuID);
	if (-1 == iIndex)
		return NULL;

	return (&m_stuObject[iIndex]);
}

////////////////////////////////////////////////////////////////////
//CStuDatabase::FindRecord

CStudent* CStuDataBase::FindRecord(char* pszStuName)
{
	if (IsEmpty())
		return NULL;

	int iIndex = GetStuIndex(pszStuName);
	if (-1 == iIndex)
		return NULL;

	return (&m_stuObject[iIndex]);
}

////////////////////////////////////////////////////////////////////
//CStuDataBase::FirstRecrod

CStudent* CStuDataBase::FirstRecord()
{
	if (IsEmpty())
		return NULL;
	else
		return (&m_stuObject[0]);
}

///////////////////////////////////////////////////////////////////
//CStuDataBase::LastRecord

CStudent* CStuDataBase::LastRecord()
{
	if (IsEmpty())
		return NULL;

	else
		return (&m_stuObject[m_RecordCount - 1]);
}

//////////////////////////////////////////////////////////////////
//CStuDataBase::GetRecord

CStudent* CStuDataBase::GetRecord(int iIndex)
{
    if (IsEmpty())
	    return NULL;

	return (&m_stuObject[iIndex]);
}

//////////////////////////////////////////////////////////////////
//CStuDataBase:PostToDataBase

bool CStuDataBase::PostToDataBase()
{
	if (IsEmpty())
		return false;
    
	//
	//删除原来的数据文件重新建立,并把新的数据重新写入
	//
	m_pfWriteFile = fopen(m_pszDataBaseName,"wb");
	if (NULL == m_pfWriteFile)
		return false;

	int iCount = 0;
	while (iCount < m_RecordCount)
	{
	    if (fwrite(&m_stuObject[iCount],sizeof(m_stuObject[iCount]),1,m_pfWriteFile) == 1)                                          
		    iCount++;
	}

	fclose(m_pfWriteFile);
	m_RecordCount = iCount;      //保存记录(数组下标)

	return true;
}

//////////////////////////////////////////////////////////////////
//CStuDataBase::GetRecordCount

int CStuDataBase::GetRecordCount()
{
	return m_RecordCount;
}

/////////////////////////////////////////////////////////////////
//CStuDataBase::GetStuIndex

int CStuDataBase::GetStuIndex(int iID)
{
	if (IsEmpty())
		return -1;

	for (int iCount = 0; iCount < m_RecordCount; iCount++)
	{
		if (m_stuObject[iCount].GetStudentID() == iID)
			return iCount;
	}

	return -1;
}

//////////////////////////////////////////////////////////////////
//CStuDataBase::GetStuIndex

int CStuDataBase::GetStuIndex(char* pszStuName)
{
	if (IsEmpty())
		return -1;

	for (int iCount = 0; iCount < m_RecordCount; iCount++)
	{
		if (!strcmp(m_stuObject[iCount].GetStudentName(),pszStuName))
			return iCount;
	}

	return -1;
}

/////////////////////////////////////////////////////////////////
//CStuDataBase::refresh

void CStuDataBase::Refresh()
{
	m_pfReadFile = fopen(m_pszDataBaseName,"rb");

	if (NULL == m_pfReadFile)
	{
		return;
	}

	rewind(m_pfReadFile);
	int iCount = 0;
	while (fread(&m_stuObject[iCount],sizeof(m_stuObject[iCount]),1,m_pfReadFile))
	{
		iCount++;
	}
	fclose(m_pfReadFile);

	m_RecordCount = iCount;
}