用C++访问DBF文件的方法

//dbf.hpp

#ifndef DBF_H
#define DBF_H

#include <stdio.h>

typedef int   BOOL;
#define MAXFIELD 100

typedef struct Column
{
 char      *name; // length <= 10
 unsigned char type;  // C-N-F-D-L-M-G
 unsigned char len;
 unsigned char dotLen;  //dot number when is N Type
} Column;

int CreateDbf(const char *fname, const Column *item);

class Cdbfile
{
 private :
  FILE  *fp;
  int   hsize;
  int   Recsize;
  long Recnum;
  int  Fieldnum;
  int   *Fieldlen;
  Column *hitem;
  long  Lookno;
 public :
  int  GetFieldidx(const char *itemname);
  long GetRecNum(void);
  int  GetFieldNum(void);
  int  GetFieldlen(int fieldno);
  int  GetFieldoff(int fieldno);
  int  GetMaxFieldlen(void);
  int  GetRecordSize(void);
  void AppendRecord(char *Recbuf);
  void *GetFieldData(long recno, const char *fname);
  BOOL SetFieldData(long recno, const char *fname, const char *buff);
  BOOL GetFieldData(long recno, const char *fname, char *buff, int bufsize=0x7FFF);
  BOOL SetFieldData(long recno, int fieldno, const char *buff);
  BOOL GetFieldData(long recno, int fieldno, char *buff, int bufsize=0x7FFF);
  long SearchSortStr(int fieldno, const char *str, BOOL igcase=0);
  long SearchStr(int fieldno, const char *str, long startno=0L);
  long SearchNextStr(int fieldno, const char *str);
  Cdbfile(const char *filename);
  ~Cdbfile(void);
  BOOL IsOpen(void);
};
#endif

//dbf.cpp

#include <dos.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

#include "dbf.hpp"

int CreateDbf(const char *fname, const Column *item)
{
 FILE *out;
 date curdate;
 int  headlen=33, reclen=1;
 char buf[32];

 if((out=fopen(fname,"wb"))==NULL)
  return 0;
 memset(buf,0,32);
 getdate(&curdate);

 buf[0] = 0x03;
 buf[1] = (char)(curdate.da_year-1970);
 buf[2] = curdate.da_mon;
 buf[3] = curdate.da_day;
 *(long*)&buf[4] = 0L; //record number
 fwrite(buf,32,1,out);

 while(item->len!=0)
 {
  memset(buf,0,32);
  strncpy(buf,item->name,10);
  strupr(buf);
  //*(int*)&buf[11] = 0x100+item->type;
  buf[11] = item->type;
  *(int*)&buf[12] = reclen;

  *(int*)&buf[16] = item->len;
  *(int*)&buf[17] = item->dotLen;
  fwrite(buf,32,1,out);
  reclen += item->len;
  headlen += 32;
  item++;
 }
 buf[0] = 0x0D;
 fwrite(buf,1,1,out);
 fseek(out,8,SEEK_SET);
 fwrite(&headlen,2,1,out);
 fwrite(&reclen,2,1,out);

 fclose(out);
 return 1;
}

Cdbfile::Cdbfile(const char *filename)
{
 int len=0;
 char *tmpbuf;

 hitem=NULL;
 Recnum=0L;
 hsize=Recsize=Fieldnum=0;

 if((fp=fopen(filename,"r+b"))==NULL) return;
 fread(&Recnum,4,1,fp);
 if(*(char*)&Recnum!=3)
 {
  fclose(fp); fp=NULL; return;
 }

 fread(&Recnum,4,1,fp);
 fread(&hsize,2,1,fp);
 Fieldnum=hsize/0x20-1;
 hsize++;

 fread(&Recsize,2,1,fp);

 hitem=new Column[Fieldnum];
 tmpbuf=new char [11*Fieldnum+2*Fieldnum];
 if(tmpbuf)
 {
  for(int i=0; i<Fieldnum; i++)
  hitem[i].name=tmpbuf+11*i;
  Fieldlen=(int*)(tmpbuf+11*Fieldnum);
 }
 else
 {
  if(hitem) delete hitem;
  hitem=NULL;
  fclose(fp);
  fp=NULL;
  return;
 }

 fseek(fp,0x20L,SEEK_SET);
 for(int i=0; i<Fieldnum; i++)
 {
  Fieldlen[i] = 0;
  if(hitem)
  {
   fread(hitem[i].name,11,1,fp);
   fread(&hitem[i].type,1,1,fp);
   fseek(fp,4L,SEEK_CUR);
   fread(&hitem[i].len,1,1,fp);
   Fieldlen[i]=hitem[i].len;
  }
  Fieldlen[i]+=len;
  len=Fieldlen[i];
  fseek(fp,15L,SEEK_CUR);
 }
}

Cdbfile::~Cdbfile(void)
{
 if(fp) fclose(fp);
 if(hitem)
 {
  delete hitem[0].name;
  delete hitem;
 }
 fp=NULL;
 hitem=NULL;
}

BOOL Cdbfile::IsOpen(void)
{
 return fp!=NULL;
}

int Cdbfile::GetFieldidx(const char *itemname)
{
 if(hitem)
  for(int i=0; i<Fieldnum; i++)
   if(stricmp(itemname,hitem[i].name)==0)
    return i;
 return -1;
}

long Cdbfile::GetRecNum(void)
{
 return Recnum;
}

int Cdbfile::GetFieldNum(void)
{
 return Fieldnum;
}

int Cdbfile::GetFieldlen(int fieldno)
{
 int len=0;

 if(Fieldnum==0) return 0;
 if(fieldno>0)
  len=Fieldlen[fieldno-1];
 return Fieldlen[fieldno]-len;
}

int Cdbfile::GetFieldoff(int fieldno)
{
 if(Fieldnum==0) return 0;
 if(fieldno>0)
  return Fieldlen[fieldno-1];
 return 0;
}

int Cdbfile::GetMaxFieldlen(void)
{
 int len=0;

 if(Fieldnum==0) return 0;
 for(int i=0; i<Fieldnum; i++)
  if(Fieldlen[i]>len)
   len=Fieldlen[i];
 return len;
}

int Cdbfile::GetRecordSize(void)
{
 return Recsize;
}

void Cdbfile::AppendRecord(char *Recbuf)
{
 long recnum;

 if(!fp) return;
 fseek(fp,0L,SEEK_END);
 fwrite(Recbuf,Recsize,1,fp);
 fseek(fp,4L,SEEK_SET);
 fread(&recnum,4,1,fp);
 recnum++;
 fseek(fp,4L,SEEK_SET);
 fwrite(&recnum,4,1,fp);
 Recnum++;
}

BOOL Cdbfile::SetFieldData(long recno, const char *fname, const char *buff)
{
 int fieldno=GetFieldidx(fname);
 if(fieldno<0) return -1;
 return SetFieldData(recno,fieldno,buff);
}

BOOL Cdbfile::SetFieldData(long recno, int fieldno, const char *buff)
{
 int num=0;
 long off;
 char outbuf[256];

 if(fp==NULL || recno<0 ||recno>=Recnum || fieldno<0 || fieldno>=Fieldnum)
  return 0;
 off=(long)hsize+recno*Recsize;
 if(fieldno)
 {
  num=Fieldlen[fieldno-1];
  off+=num;
 }
 fseek(fp,off,SEEK_SET);

 num=Fieldlen[fieldno]-num;

 memset(outbuf,0x20,num);
 memcpy(outbuf,buff,strlen(buff));

 fwrite(outbuf,num,1,fp);
 return 1;
}

void *Cdbfile::GetFieldData(long recno, const char *fname)
{
 char *buff;
 int fieldno, size;

 fieldno=GetFieldidx(fname);
 if(fieldno<0)
  return NULL;
 size = Fieldlen[fieldno];
 if(fieldno)
  size -= Fieldlen[fieldno-1];
 buff=new char [size+1];
 if(buff)
  GetFieldData(recno,fieldno,buff);
 return buff;
}

BOOL Cdbfile::GetFieldData(long recno, const char *fname, char *buff, int bufsize)
{
 buff[0] = 0;
 int fieldno=GetFieldidx(fname);
 if(fieldno<0) return -1;
 return GetFieldData(recno,fieldno,buff,bufsize);
}

BOOL Cdbfile::GetFieldData(long recno, int fieldno, char *buff, int bufsize)
{
 int num=0;
 long off;

 buff[0] = 0;
 if(fp==NULL || recno<0 || recno>=Recnum || fieldno<0 || fieldno>=Fieldnum)
  return 0;
 off=(long)hsize+recno*(Fieldlen[Fieldnum-1]+1);
 if(fieldno)
 {
  num=Fieldlen[fieldno-1];
  off+=num;
 }
 fseek(fp,off,SEEK_SET);

 num=Fieldlen[fieldno]-num;

 if(num>=bufsize)
 {
  printf("buffer overflow!/n");
  exit(3);
 }
 fread(buff,num,1,fp);
 if(toupper(hitem[fieldno].type)=='C')
 {
  while(num>=0 && buff[--num]==' ') ;
  num++;
 }
 buff[num] = 0;
 return 1;
}

long Cdbfile::SearchSortStr(int fieldno, const char *str, int igcase)
{
 long temp;
 long leftno = 0L;
 long rightno = Recnum;
 int  l2 = GetFieldlen(fieldno);

 if(fp==NULL || fieldno<0 || fieldno>=Fieldnum) return -1;
 while(leftno<=rightno)
 {
  char *buf = new char [l2];

  temp = (leftno+rightno)>>1;
  GetFieldData(temp,fieldno,buf);

  int val;
  if(igcase)
   val = stricmp(buf,str);
  else
   val = strcmp(buf,str);

  delete buf;

  if(val==0) return temp;
  if(val>0)
   rightno = temp-1;
  else
   leftno = temp+1;
 }
 return -1;
}

long Cdbfile::SearchStr(int fieldno, const char *str, long startno)
{
 int l2 = GetFieldlen(fieldno);

 if(fp==NULL || startno<0 || startno>=Recnum || fieldno<0 || fieldno>=Fieldnum)
  return -1;
 char *buf = new char [l2];
 for(long i=startno; i<Recnum; i++)
 {
  GetFieldData(i,fieldno,buf);

  if(stricmp(str,buf)==0)
  {
   Lookno = i+1;
   delete buf;
   return i;
  }
 }
 delete buf;
 return -1;
}

long Cdbfile::SearchNextStr(int fieldno, const char *str)
{
 if(Lookno<0) return -1;
 return(SearchStr(fieldno,str,Lookno));
}