find.cpp

金融pos机前台源码

/*******************************************************************************
	模  块:	查询数据库.
	功  能:	按编码和条码查询数据库,返回查询结果.
	程序员:	雷中南.
	版  本:	v1.0
	时  间:	1999-05-18
*******************************************************************************/
#include <stdlib.h>
#include <string.h>
#include <io.h>
#include <def.h>
#include "find.h"

//构造函数.
Find::Find(char *datafname, char *indexfname)
{
	//记录数据文件名信息.
	strcpy(DataFName, datafname);
	RecordLen = 109;
	FileLen = GetFileLength(DataFName);
	RecordNum = FileLen / RecordLen;

	//记录索引文件信息.
	strcpy(IndexFName, indexfname);
	iRecordLen = 29;
	iFileLen = GetFileLength(IndexFName);
	iRecordNum = iFileLen / iRecordLen;
}

//析构函数.
Find::~Find()
{
}

//获取文件长度.
long
Find::GetFileLength(char *filename)
{
	FILE *fp;
	fp = fopen(filename, "rb");
	long filelen = filelength(fileno(fp));
	fclose(fp);
	return filelen;
}

//从数据文件中读取数据.
int
Find::Read(long ID)
{
	//将文件指针移到指定记录.
	if(fseek(DataFile, ID*((long)RecordLen), 0)!=0)
	{
		return L_ERROR;
	}
	//读记录.
	if(fread(Buffer, RecordLen, 1, DataFile)==0)
	{
		return L_ERROR;
	}
	//设定临时指针.
	char *temp = Buffer;
	//将数据赋给字段.
	memcpy((void *)BarCode, temp, 14);
		temp += 14;
		BarCode[13] = NULL;
	memcpy((void *)Code, temp, 14);
		temp += 14;
		Code[13] = NULL;
	memcpy((void *)Name, temp, 25);
		temp += 25;
		Name[24] = NULL;
		strcpy(Name, Trim(Name));
	memcpy((void *)Price, temp, 10);
		temp += 10;
		Price[9] = NULL;
	memcpy((void *)VipPrice1, temp, 10);
		temp += 10;
		VipPrice1[9] = NULL;
	memcpy((void *)VipPrice2, temp, 10);
		temp += 10;
		VipPrice2[9] = NULL;
	memcpy((void *)VipPrice3, temp, 10);
		temp += 10;
		VipPrice3[9] = NULL;
	memcpy((void *)PrefPrice, temp, 10);
		temp += 10;
		PrefPrice[9] = NULL;
	memcpy((void *)Type, temp, 5);
		temp += 5;
		Type[4] = NULL;
	return L_OK;
}

int
Find::ReadNull()
{
	//设定临时指针.
	strcpy(BarCode, "0000000000000");
	strcpy(Code, "000000000000*");
	strcpy(Name, "无编码销售");
	strcpy(Price, "1.00");
	strcpy(VipPrice1, "1.00");
	strcpy(VipPrice2, "1.00");
	strcpy(VipPrice3,	"1.00");
	strcpy(PrefPrice, "1.00");
	strcpy(Type, "0000");
	return L_OK;
}

//读索引文件.
int
Find::iRead(long ID)
{
	//将文件指针移到指定记录.
	if(fseek(IndexFile, ID*((long)iRecordLen), 0)!=0)
	{
		return L_ERROR;
	}
	//读记录.
	if(fread(iBuffer, iRecordLen, 1, IndexFile)==0)
	{
		return L_ERROR;
	}
	char *temp = iBuffer;
	memcpy((void *)iBarCode, temp, 14);
		temp += 14;
		iBarCode[13] = NULL;
	memcpy((void *)iCode, temp, 14);
		temp += 14;
		iCode[13] = NULL;
	return L_OK;
}

//查找数据文件.
int
Find::SearchCode(char *code)
{
	char temp[14];
	if(strcmp("000000000000*", code) == 0)
	{
		ReadNull();
		return L_OK;
	}
	//打开数据文件.
	if((DataFile = fopen(DataFName, "rb")) == NULL)
	{
		fclose(DataFile);
		return L_ERROR;
	}
	strncpy(temp, code, 13);
	temp[13] = NULL;
	long head = 0L, tail = RecordNum, current, answ;
	current = (head + tail) / 2;
re:
	//读取指定位置.
	Read(current);
	//比较字符串.
	answ = strcmp(temp, Code);
	//如果相同.
	if(answ == 0)
	{
		fclose(DataFile);
		return L_OK;
	}
	//如果头尾相邻.
	if(labs(head - tail) <= 1)
	{
		//读头记录.
		Read(head);
		//比较.
		answ = strcmp(temp, Code);
		//相同.
		if(answ == 0)
		{
			fclose(DataFile);
			return L_OK;
		}
		//读尾记录.
		Read(tail);
		//比较.
		answ = strcmp(temp, Code);
		//相同.
		if(answ == 0)
		{
			fclose(DataFile);
			return L_OK;
		}
		//如果此时头尾都不符合条件,则认为没有符合条件记录.
		fclose(DataFile);
		return L_ERROR;
	}
	if(answ > 0)//如果比较结果大于0.
	{
		//头折半.
		head = current;
		current = (head + tail) / 2;
		goto re;
	}
	if(answ < 0)//如果比较结果小于0.
	{
		//尾折半.
		tail = current;
		current = (head + tail) / 2;
		goto re;
	}
	return L_ERROR;
}

//查找索引文件.
int
Find::SearchBarCode(char *barcode)
{
	//打开索引文件.
	if((IndexFile = fopen(IndexFName, "rb")) == NULL)
	{
		fclose(IndexFile);
		return L_ERROR;
	}
	long head=0, tail=iRecordNum, current, answ;
	current = (head + tail) / 2;
re:
	//从索引文件读取数据.
	iRead(current);
	//比较.
	answ = strcmp(barcode, iBarCode);
	//符合.
	if(answ == 0)
	{
		fclose(IndexFile);
		return L_OK;
	}
	//如果头尾相邻.
	if(labs(head - tail) <= 1)
	{
		//读头记录.
		iRead(head);
		//比较.
		if(strcmp(barcode, iBarCode) == 0)
		{
			fclose(IndexFile);
			return L_OK;
		}
		//读尾记录.
		iRead(tail);
		//比较.
		if(strcmp(barcode, iBarCode) == 0)
		{
			fclose(IndexFile);
			return L_OK;
		}
		//如果此时头尾都不符合条件,则认为没有符合条件记录.
		fclose(IndexFile);
		return L_ERROR;
	}
	if(answ > 0)//如果比较结果大于0.
	{
		//头折半.
		head = current;
		current = (head + tail) / 2;
		goto re;
	}
	if(answ < 0)//如果比较结果小于0.
	{
		//尾折半.
		tail = current;
		current = (head + tail) / 2;
		goto re;
	}
	return L_ERROR;
}

//综合查询.
int
Find::Search(char *data)
{
	FileLen = GetFileLength(DataFName);
	RecordNum = FileLen / RecordLen;
	iFileLen = GetFileLength(IndexFName);
	iRecordNum = iFileLen / iRecordLen;
	//由于使用中条码较多,所以先按条码查询.
	if(SearchBarCode(data)==L_ERROR)
	{
		//不存在条码,按编码查询.
		if(SearchCode(data)==L_ERROR)
		{
			return L_ERROR;
		}
		else
		{
			return L_OK;
		}
	}
	else
	{
		//存在条码,先读取条码对应编码,按编码再查询.
		if(SearchCode(iCode)==L_ERROR)
		{
			return L_ERROR;
		}
		else
		{
			return L_OK;
		}
	}
}