我一直在我的 C++ 编程书中做一个练习，它基本上要求我创建一个程序，该程序将包含 3 个文件，一个旧的客户数据主文件（帐户、名称、余额）、一个交易文件（帐户名称和贷方或借方），然后是合并这些文件并输出新的客户数据主文件的函数。我很确定我知道如何做到这一点，或者即使我不知道，我想我也能弄明白，我遇到的问题是一个简单的选择选择界面，它的实现与另一个工作的程序完全相同美好的。当我第一次运行程序时，它会让我输入一个选项（int），然后运行适当的函数（其中我只有 1 个完全实现，即 createMasterFile 函数。然后点击 switch 语句，它以某种方式将选择更改为 0，然后点击默认情况，然后返回到 while 语句，并且选择的值为 32767，并且似乎再次跳过了 while 语句的条件部分并陷入无限在这一点上循环，选择永远不会改变价值。在一个非常相似的程序中（唯一的区别是工作的程序使用二进制文件而不是顺序文件）这工作得很好。界面如下所示：
enum Choices {CREATE_MASTER =1, CREATE_TRANSACTION, SORT_MASTER, UPDATE_MASTER, SORT_TRANS, UPDATE_TRANS, MERGE, END };
int choice;
while ( ( choice = enterChoice()) != END )
{
switch( choice )
{
case CREATE_MASTER:
createMasterFile( inOutOldMasterFile );
break;
case CREATE_TRANSACTION:
break;
case SORT_MASTER:
break;
case UPDATE_MASTER:
break;
case SORT_TRANS:
break;
case UPDATE_TRANS:
break;
case MERGE:
break;
default:
cerr << "Incorrect choice" << endl;
break;
}
}
enterchoice() 函数是：
int enterChoice()
{
cout << "\nEnter your choice below" << endl
<< "1 - Create Master Record" << endl
<< "2 - Create Transaction Record" << endl
<< "3 - Sort Master File In Descending Order" << endl
<< "4 - Update Master File" << endl
<< "5 - Sort Transaction File" << endl
<< "6 - Update Transaction File" << endl
<< "7 - Merge Transaction and Old Master File" << endl
<< "8 - End Program\n?";
int choice;
cin >> choice;
return choice;
}
如果您需要在这里查看所有代码（只是为了清楚起见）（对于当前正在使用的功能）
#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>
#include <cstdlib>
using namespace std;
void outputLine( int, const string, double );
void createMasterFile( fstream & );
int numberOfAccounts = 0;
void swap(int * const, int * const);
void swap( string * const, string * const);
void swap( double * const, double * const);
bool descending( int, int);
void sortAccounts(int, fstream &, bool (*)(int, int));
int enterChoice();
int main()
{
// create a fstream object for input and output to be passed to
// the functions that need to manipulate it.
fstream inOutOldMasterFile( "oldmaster.dat", ios::in | ios::out );
fstream inOutTransaction( "trans.dat", ios::in | ios::out );
ofstream outNewMaster( "newmaster.dat", ios::out);
enum Choices {CREATE_MASTER =1, CREATE_TRANSACTION, SORT_MASTER, UPDATE_MASTER, SORT_TRANS, UPDATE_TRANS, MERGE, END };
int choice;
while ( ( choice = enterChoice()) != END )
{
switch( choice )
{
case CREATE_MASTER:
createMasterFile( inOutOldMasterFile );
break;
case CREATE_TRANSACTION:
break;
case SORT_MASTER:
break;
case UPDATE_MASTER:
break;
case SORT_TRANS:
break;
case UPDATE_TRANS:
break;
case MERGE:
break;
default:
cerr << "Incorrect choice" << endl;
break;
}
}
return 0;
}
int enterChoice()
{
cout << "\nEnter your choice below" << endl
<< "1 - Create Master Record" << endl
<< "2 - Create Transaction Record" << endl
<< "3 - Sort Master File In Descending Order" << endl
<< "4 - Update Master File" << endl
<< "5 - Sort Transaction File" << endl
<< "6 - Update Transaction File" << endl
<< "7 - Merge Transaction and Old Master File" << endl
<< "8 - End Program\n?";
int choice;
cin >> choice;
return choice;
}
void createMasterFile( fstream &clientFile )
{
if(!clientFile)
{
clientFile.open("oldmaster.dat", ios::in | ios::out);
}
cout << "Enter the account, name and balance." << endl
<< "Enter end-of-file to end input (^d)\n? ";
int account;
string name;
double balance;
clientFile.seekp( 0, ios::beg );
// read account, name and balance from cin then place in file
while (cin >> account >> name >> balance )
{
numberOfAccounts++;
clientFile << account << ' ' << name << ' ' << balance << endl;
cout << "?";
} //end while
clientFile.seekg( 0, ios::beg );
cout << left << setw(10) << "Account" << setw(13)
<< "Name" << "Balance" << endl << fixed << showpoint;
while( clientFile >> account >> name >> balance)
{
outputLine( account, name, balance );
}
clientFile.close();
}
如果这真的很明显，我很抱歉，但我已经尝试在网上搜索近 2 天来找到一些答案。
提前致谢。
-鲍比