二进制结构删除错误
Binary structure delete error
这是整个程序。现在，delete函数不写入临时文件。我将尝试将str数组更改为string，看看是否有帮助。
程序应该能够读、写、编辑、搜索和排序有结构的二进制文件。
#include <cstdlib>
#include <stdlib.h>
#include <iostream>
#include <fstream>
#include<string>
#include<limits>
#include<iomanip>
#include<stdio.h>
#include <errno.h>
using namespace std;
const int SIZE=40;
char typedef str[SIZE];
char fname[]="c:/solident.dat";
char tname[]="c:/temp.dat";
struct Rec{int id;str lname,fname;};
//prototypes
void menu(string&);
void engine(string&,Rec&,fstream&,fstream&,int,char[],char[]);
void openFile(char[]);
void addRec(Rec&,char[]);
void delAll(char[]);
void listAll(Rec&,fstream &,char[]);
void appRec(Rec&,fstream &,char[]);
void delRec(Rec&,fstream &, fstream &,char[],char []);
void srcRec(Rec&,fstream& ,char[]);
void modRec(Rec &J,fstream &outfile, char fname[]);
void sort();
int main(int argc, char *argv[])
{
string choice;
Rec Student;
fstream infile;
fstream outfile;
do
{
menu(choice);
engine(choice,Student,infile,outfile,SIZE,fname,tname);
} while(choice[0]!='0');
system("PAUSE");
return EXIT_SUCCESS;
}
//function menu
void menu(string &choice)
{
cout<<"nnntt========================";
cout<<"nnttMENU n";
cout<<"ntt========================nn";
cout<<"tt[1] Open/check filen";
cout<<"tt[2] Add recordsn";
cout<<"tt[3] Append recordsn";
cout<<"tt[4] Search for a recordn";
cout<<"tt[5] Delete a recordn";
cout<<"tt[6] Delete all recordsn";
cout<<"tt[7] Modify a recordn";
cout<<"tt[8] List all recordsn";
cout<<"tt[9] Sort all recordsn";
cout<<"tt[0] Exitn";
cout<<"ntt========================= n";
cout<<"ttYour choice :";
getline(cin,choice);
while (choice[0] !='1' && choice[0] !='2' &&choice[0] !='3' &&choice[0] !='4' &&choice[0] !='5' &&choice[0] !='6' &&choice[0] !='7' &&choice[0] !='8' &&choice[0] !='9' &&choice[0] !='0' )
{
cout<<"ntt"<<choice<<" is invalid!";
cout<<"nttEnter correct choice: ";
getline(cin,choice);
}
cout<<"ntt========================= nn";
}
//function
void engine(string &choice,Rec &J,fstream &infile,fstream &outfile,int SIZE,char fname[],char tname[])
{
switch (choice[0]){
case '1':
{
cout<<"Executing number "<<choice<<":"<<"Open/check filen"<<endl;
openFile(fname);
break;
}
case '2':
{
cout<<"Executing number "<<choice<<":"<<"Add recordsn"<<endl;
addRec(J,fname);
break;
}
case '3':
{
cout<<"Executing number "<<choice<<":"<<"Append recordsn"<<endl;
appRec(J,outfile,fname);
break;
}
case '4':
{
cout<<"Executing number "<<choice<<":"<<"Search for a recordn"<<endl;
srcRec(J,infile,fname);
break;
}
case '5':
{
cout<<"Executing number "<<choice<<":"<<"Delete a recordn"<<endl;
delRec(J,infile, outfile,fname,tname);
break;
}
case '6':
{
cout<<"Executing number "<<choice<<":"<<"Delete all recordsn"<<endl;
delAll(fname);
break;
}
case '7':
{
cout<<"Executing number "<<choice<<":"<<"Modify a recordn"<<endl;
modRec(J,outfile,fname);
break;
}
case '8':
{
cout<<"Executing number "<<choice<<":"<<"List all recordsn"<<endl;
listAll(J,infile,fname);
break;
}
case '9':
{
cout<<"Executing number "<<choice<<":"<<"Sort all recordsn"<<endl;
sort();
break;
}
default:exit(0);
}
}
//function
void openFile(char fname[])
{
cout<<"nOpening file"<<fname<<"..."<<endl;
//confirm if file exists and opens
fstream infile;
fstream outfile;
infile.open(fname,ios::in|ios::binary);
if (infile.is_open())
{
cout<<"File "<<fname<<" exists, and was opened succesfully.";
}
infile.close();
//if fail ask to create
if (infile.fail())
{
cout<<"File does not exist. Create? [Y]/[N]";
char ch;
cin>>ch;
cin.ignore(numeric_limits<streamsize>::max(), 'n');
//if yes then create file
if(ch=='y'|| ch=='Y')
outfile.open(fname,ios::out| ios::binary);
//if not created display error
if (outfile.fail())
{
cout<<"Error: File not created";
}
//else confirm creation of file
cout<<"File "<<fname<<" has been created.nn";
outfile.close();
}
}
//function
void addRec(Rec&J,char fname[])
{
fstream outfile;
outfile.open(fname,ios::out|ios::binary|ios::app);
char another[10];
do
{
cout<<"Please enter ID number :";
cin>>J.id;
cin.ignore(numeric_limits<streamsize>::max(), 'n');
cout<<"nPlease enter first name: ";
cin.getline(J.fname,SIZE);
cout<<"nPlease enter lastname: ";
cin.getline(J.lname,SIZE);
outfile.write((char*) &J, sizeof(J));
cout<<"Add another record:[Y]/[N] ";
cin.get(another[0]);
cin.ignore(numeric_limits<streamsize>::max(), 'n');
} while(another[0]=='y'||another[0]=='Y');
cout<<"exiting to main menu.."<<endl;
}
//function
void delAll(char fname[])
{
fstream outfile;
cout<<"n------------------n"<<endl;
cout<<"nDelete all records"<<fname<<"..."<<endl;
cout<<"nAre you sure you want to delete all records in "<<fname<<" [Y]/[Any key for exit]?"<<endl;
char ch;
cin>>ch;
cin.ignore(numeric_limits<streamsize>::max(), 'n');
if(ch=='y'||ch=='Y')
{
outfile.open(fname,ios::out|ios::binary|ios::trunc);
outfile.close();
}
else {cout<<"nExiting to main menu..."<<endl;}
}
//function
void listAll(Rec&J,fstream &infile,char fname[])
{
infile.clear();
infile.open(fname,ios::in|ios::binary);
infile.read((char*)&J,sizeof(J));
cout<<"|=======================================================|"<<endl;
cout<<"| # | ID | FIRST | LAST |"<<endl;
cout<<"|=======================================================|"<<endl;
int count=1;
while(!infile.eof())
{
cout<<"| "<<setw(6)<<left<<count<<left<<"| "<<setw(9)<<J.id<<"| ";
cout<<left<<setw(14)<<J.fname<<"| ";
cout<<left<<setw(19)<<J.lname<<"|"<<endl;
infile.read((char*)&J,sizeof(J));
count=count+1;
cout<<"|-------------------------------------------------------|"<<endl;
}
infile.close();
}
//function
void appRec(Rec &J,fstream &outfile, char fname[])
{
outfile.open(fname,ios::out|ios::binary|ios::app);
outfile.clear();
cout<<"Please enter ID number :";
cin>>J.id;
cin.ignore(numeric_limits<streamsize>::max(), 'n');
cout<<"nPlease enter first name: ";
cin.getline(J.fname,SIZE);
cout<<"nPlease enter lastname: ";
cin.getline(J.lname,SIZE);
outfile.write((char*) &J, sizeof(J));
outfile.close();
}
//----------------------------------------------------
void delRec(Rec&s,fstream &infile, fstream &outfile,char fname[],char tname[])
{
int current, request=1;
infile.open("c:/solident.dat",ios::in|ios::out|ios::binary);
if (!infile.is_open())
cout << "infile not openn";
outfile.open("c:/temp.dat",ios::out|ios::binary|ios::trunc);
if (!outfile.is_open())
cout << "outfile not openn";
for (;;)
{
infile.read((char*)&s, sizeof s);
if (infile.eof())
break;
current = s.id;
if (current != request)
outfile.write((char*)&s, sizeof s);
}
infile.close();
outfile.close();
infile.open("c:/temp.dat)",ios::in|ios::binary);
outfile.open("c:/solident.dat)", ios::out|ios::binary|ios::trunc);
for (;;)
{
infile.read((char*)&s, sizeof (s));
if (infile.eof())
break;
outfile.write((char*)&s, sizeof (s));
}
infile.close();
outfile.close();
}
void srcRec(Rec&Job,fstream &infile,char fname[])
{
cout << "Allowing the user to open a specific record.n";
infile.open(fname, ios::in | ios::binary) ;
if(infile.fail())
{
cout << "Could not access file.n";
}
else
{
int position; //user's position
//gets user's position
cout << "Please the record you would like to read: ";
cin >> position;
//ignore luki
cin.ignore(numeric_limits<streamsize>::max(), 'n');
//find the specific record, read it, and display it
infile.seekp((position - 1)*sizeof(Job));
infile.read((char*) &Job, sizeof(Job));
cout<<"|===============================================|"<<endl;
cout<<"| ID | FIRST | LAST |"<<endl;
cout<<"|===============================================|"<<endl;
cout<<left<<"| "<<setw(9)<<Job.id<<"| ";
cout<<left<<setw(14)<<Job.fname<<"| ";
cout<<left<<setw(19)<<Job.lname<<"|"<<endl;
}
//clears and closes the file
infile.clear();
infile.close();
}
void modRec(Rec &J,fstream &outfile, char fname[])
{
int position, //user's position
cntr = 0; //marks the current record within the file
cout << "Modifying a record.n";
//open the two files
outfile.open(fname, ios::out | ios::in | ios::binary);
//get the user's desired position
cout << "please enter the record you would like to modify: ";
cin >> position;
cin.ignore(numeric_limits<streamsize>::max(), 'n');
cout << endl;
if(outfile.fail())
{
cout << "File could not be read.n";
}
else
{
//find the desired record
outfile.seekp((position - 1)*(sizeof(J)));
//get the user's modification
cout<<"Please enter ID number :";
cin>>J.id;
cin.ignore(numeric_limits<streamsize>::max(), 'n');
cout<<"nPlease enter first name: ";
cin.getline(J.fname,SIZE);
cout<<"nPlease enter lastname: ";
cin.getline(J.lname,SIZE);
//write over the desired record
outfile.write((char*) &J, sizeof(J));
}
//closes the files
outfile.close();
}
void sort()
{
int StructureSize, Idx1, Idx2;
FILE * binaryFile;
binaryFile = fopen("c:/solident.dat","rb+");
Rec Index, IndexTemp;
StructureSize = sizeof(Index);
fseek(binaryFile, 0, SEEK_END);
int fileSize = ftell(binaryFile);
rewind(binaryFile);
for (Idx1 = 0; Idx1 < fileSize; Idx1 += StructureSize)
{
for (Idx2 = 0; Idx2 < fileSize - StructureSize; Idx2 += StructureSize)
{
fread(&Index, StructureSize, 1, binaryFile);
fread(&IndexTemp, StructureSize, 1, binaryFile);
if (Index.id > IndexTemp.id)
{
fseek(binaryFile, -(StructureSize * 2), SEEK_CUR);
fwrite(&IndexTemp, StructureSize, 1, binaryFile);
fwrite(&Index, StructureSize, 1, binaryFile);
fseek(binaryFile, -StructureSize, SEEK_CUR);
}
else
{
fseek(binaryFile, -StructureSize, SEEK_CUR);
}
}
rewind(binaryFile);
}
fclose(binaryFile);
}
我不知道，这段代码似乎有一些问题。这只是其中之一
int request=1,current;
...
while (!infile.eof())
{
s.id=current;
if (current!=request)
在这段代码中，您没有给current一个值，但您仍然在使用该变量。这是一个未初始化的变量，这是你的代码不能工作的原因之一。
我想知道你是否打算写
current=s.id;
?这样就更有意义了。
尝试使用如下循环读取文件
infile.open("c:/solident.dat",ios::in|ios::out|ios::binary);
if (!infile.is_open())
cout << "infile not openn";
outfile.open("c:/temp.dat",ios::out|ios::binary|ios::trunc);
if (!outfile.is_open())
cout << "outfile not openn";
for (;;)
{
infile.read((char*)&s, sizeof s);
if (infile.eof())
break;
current = s.id;
if (current != request)
outfile.write((char*)&s, sizeof s);
}
infile.close();
outfile.close();
如果我是你，我就不会用fail()。我认为用它来检测真正的读写失败是极不可能的。这更有可能是文件结束错误，或者打开文件失败。
@john .谢谢!第一部分是有效的，但仍在尝试Rename (tempname,destination)不起作用:(dest文件存在)
虽然temp.dat文件现在包含减去删除的记录，但输出不会写入solident.dat文件(它保持不变)
//所以我尝试从文件中读取每条记录，并将每条记录写入dest文件:
infile.open("c:/temp.dat)",ios::in|ios::binary);
outfile.open("c:/solident.dat)", ios::out|ios::binary|ios::trunc);
infile.read((char*)&s, sizeof s);
for (;;)
{
if (infile.eof())
break;
infile.read((char *)&s, sizeof (s));
outfile.write((char*)&s, sizeof (s));
}
infile.close ();
outfile.close ();我的理解是，outfile和inffile非常简单:fstream。打开，关闭，清晰，它应该工作(我想)。似乎我错过了一些重要的东西，因为程序中简单的delete二进制结构函数似乎是命中注定的，我已经绕了几天了:它的一部分工作，然后我添加了几行代码，要么函数失败，要么整个程序失败。我倾向于将其归咎于编译器或devc++:)，但我确信它必须是无效的代码!
谢谢你的帮助!
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