你的程序让我很感兴趣，因为我没有对 iostream 做太多的工作。如果您曾经处理必须基于每条记录进行编辑的数据，您将使用某种类型的数据库或专门的库来封装所有这些东西，例如 xml 库。由于您的数据非常小，因此使用数据结构数组将所有数据加载到您的应用程序中会更容易。之后，当您有新的用户输入时，最简单的方法是清除文件，然后重新写入数据。这就是我所做的。
#include <stdio.h>
#include <tchar.h>
#include <iostream> // cin, cout
#include <iomanip>
#include <fstream>
#include <conio.h>
using namespace std;
#define SIZE 10
#define BUFFER_SIZE 100
#define NAME_SIZE 20
struct client // Client record
{
int account; // from 1 to SIZE
char name[NAME_SIZE];
double balance;
};
/* Makes file if files does not exist.
* Returns true if file already exists
*/
bool make_file(char filename[], int number_of_records)
{
// Check if file exists
fstream file;
file.open(filename, ios_base::out | ios_base::in); // will not create file
if (file.is_open())
{
file.close();
return true;
}
else
{
file.clear();
file.open(filename, ios_base::out);
if(!file) {cerr << "File open error." << endl; exit(1);}
cout << "File created. \n";
file.close();
return false;
}
}
/* Create an application that reads x number of accounts from a text file
* into an array of client data structures.
*/
int _tmain(int argc, _TCHAR* argv[])
{
client clientArray[SIZE];
char cleanName[NAME_SIZE];
for(int i = 0; i < NAME_SIZE; i++)
cleanName[i] = NULL;
// Make file if doesn't not exist.
char *fname = "credit.txt";
bool fileExisted = false;
fileExisted = make_file(fname, SIZE);
// initialize client array
for(int j = 0; j < SIZE; j++)
{
clientArray[j].account = -1;
strcpy_s(clientArray[j].name, cleanName);
clientArray[j].balance = 0.0;
}
// Open file and populate the client array
fstream readFile("credit.txt", ios::in | ios::binary);
if(fileExisted)
{
if(!readFile)
{
cerr<<"File open error! "<<endl;
exit(1);
}
int index = 0;
bool firstRun = true;
client temp;
while(index < SIZE)
{
readFile >> temp.account;
readFile >> temp.name;
readFile >> temp.balance;
if(readFile.eof())
break;
if(firstRun)
{
cout << "Data read \n";
cout << "----------\n";
firstRun = false;
}
clientArray[index].account = temp.account;
strcpy_s(clientArray[index].name, temp.name);
clientArray[index].balance = temp.balance;
cout << setw(3) << index+1;
cout << setw(6) << clientArray[index].account;
cout << setw(20) << clientArray[index].name;
cout << setw(10) << clientArray[index].balance << "\n";
index++;
}
readFile.close();
readFile.clear();
}
// Get user input
{
client temp; // Create and initialize temp client
temp.account = 0;
temp.balance = 0;
strcpy_s(temp.name, cleanName);
int index = 0;
bool keepLooping = true;
while(keepLooping)
{
cout << "Account[1.."<< SIZE << "], Name, Balance (-1 to exit)= ";
cin >> temp.account;
// If user exited
if(temp.account == -1)
keepLooping = false;
else
{
cin >> temp.name; // If not keep reading data
cin >> temp.balance;
// Find either unused account or same account
bool found = false;
int firstEmpty = -1;
for(int i = 0; i<SIZE; i++)
{
if(temp.account == clientArray[i].account) // Same account found
{
strcpy_s(clientArray[i].name, temp.name);
clientArray[i].balance = temp.balance;
found = true;
break;
}
else if((clientArray[i].account == -1)&&(firstEmpty == -1)) // Empty account found
{
firstEmpty = i;
}
}
if((firstEmpty != -1)&&(!found)) // Copy input to empty account
{
clientArray[firstEmpty].account = temp.account;
strcpy_s(clientArray[firstEmpty].name, temp.name);
clientArray[firstEmpty].balance = temp.balance;
}
else if(found) //
{
cout << "Updating Client Data. \n";
}
else // No empty accounts break loop
{
cout << "Client array is full!\n";
keepLooping = false;
}
}
}
} // end of user input scope
// Clear file and write only valid data to new file
{
ofstream out;
out.open("credit.txt");
for(int i=0 ; i<SIZE ; i++)
{
if(clientArray[i].account != -1)
{
out << clientArray[i].account << "\t";
out << clientArray[i].name << "\t";
out << clientArray[i].balance << "\n";
}
}
out.close();
out.clear();
}
// Open file and read the data
{
ifstream readFile("credit.txt", ios::in | ios::binary);
// readFile("credit.txt", ios::in | ios::binary);
if(!readFile)
{
cerr<<"File open error! "<<endl;
exit(1);
}
if(!readFile.good())
{
cerr<<"File open error!2"<<endl;
exit(1);
}
int index = 0; // scope variables
client temp;
temp.account = 0;
temp.balance = 0;
strcpy_s(temp.name, cleanName);
cout << "\nAccounts" << "\n";
cout << "----------" << "\n";
bool readFileb = readFile.good();
while(index < SIZE)
{
readFile >> temp.account;
readFile >> temp.name;
readFile >> temp.balance;
if(readFile.eof())
break;
cout << setw(3) << index+1;
cout << setw(6) << temp.account;
cout << setw(20) << temp.name;
cout << setw(10) << temp.balance << "\n";
index++;
}
readFile.close();
readFile.clear();
}
system("pause");
}