示例.cpp我的讲师提供了导致控制台在我输入文件名后挂起，因为它达到我认为是SalesRecord_Array read_records(ifstream& in, int &n)中的for（）的最后一个循环
#include <iostream>
#include <fstream>
#include <iomanip>
#include <cstdlib>
#include <string>
#include "sort.h"
using namespace std;
const int MAX_FILE_NAME = 35;
const int MAX_ID_LEN = 10;
const int MAX_NAME_LEN = 20;
const int RATE_CHANGE_POINT = 500;
const double RATE1 = 0.50;
const double RATE2 = 0.60;
class SalesRecord
{ private:
char emp_id[MAX_ID_LEN + 1];
char emp_name[MAX_NAME_LEN +1];
int quantity_sold;
double commission_rate;
double commission;
public:
SalesRecord();
void read(ifstream& in);
void calc_commission();
void write(ostream & os) const;
bool operator<(const SalesRecord& right) const;
};
typedef SalesRecord * SalesRecord_Array;
void open_input(ifstream& input, char name[]);
void open_output(ofstream& output, char name[]);
SalesRecord_Array read_records(ifstream& in, int &n);
void calc_records(SalesRecord_Array records, int n);
void write_records(SalesRecord_Array records, int n);
int main()
{ char again;
int num_records;
char infilename[MAX_FILE_NAME + 1];
ifstream in;
SalesRecord_Array records = NULL;
do
{ open_input(in, infilename);
records = read_records(in, num_records);
in.close();
if (records != NULL && num_records > 0)
{ calc_records(records, num_records);
sort(records, num_records);
write_records(records, num_records);
delete [] records;
}
else
{ cout << "\n\n\aNo data in file: " << infilename << endl;
}
cout << "\nDo you want to process another file (Y/N)? ";
cin >> again;
cin.ignore(256, '\n');
} while ( again == 'y' || again == 'Y');
cout << "\n\n***** END OF PROGRAM ******\n";
return 0;
}
void open_input(ifstream& input, char name[])
{ int count = 0;
do
{ count++;
if (count != 1)
{ cout << "\n\aInvalid file name or file does not exist. Please try again." << endl;
}
cout << "\nEnter the input file name (maximum of " << MAX_FILE_NAME << " characters please)\n:> ";
cin.get(name, MAX_FILE_NAME + 1);
cin.ignore(256, '\n');
input.clear();
input.open(name, ios_base::in);
} while (input.fail() );
}
void open_output(ofstream& output, char name[])
{ int count = 0;
do
{ count++;
if (count != 1)
{ cout << "\n\aInvalid file name. Please try again." << endl;
}
cout << "\nEnter the output file name (maximum of " << MAX_FILE_NAME << " characters please)\n:> ";
cin.get(name, MAX_FILE_NAME + 1);
cin.ignore(256, '\n');
output.clear();
output.open(name);
} while (output.fail() );
}
SalesRecord::SalesRecord()
{ emp_id[0] = emp_name[0] ='\0';
quantity_sold = 0;
commission_rate = commission = 0.0;
}
void SalesRecord::read(ifstream& in)
{ in.get(emp_id, MAX_ID_LEN +1);
while (in.get() != '\n');
in.get(emp_name, MAX_NAME_LEN +1);
while (in.get() != '\n');
in >> quantity_sold;
while (in.get() != '\n');
}
void SalesRecord::calc_commission()
{ if (quantity_sold < RATE_CHANGE_POINT)
commission_rate = RATE1;
else
commission_rate = RATE2;
commission = commission_rate * quantity_sold;
}
void SalesRecord::write(ostream & os) const
{ os.setf(ios::fixed); os.setf(ios::showpoint); os.precision(2);
os << emp_id << "\n" << emp_name << "\n"
<< quantity_sold << " " << commission_rate << " "
<< commission << endl;
}
bool SalesRecord::operator<(const SalesRecord& right) const
{ if (stricmp(emp_name, right.emp_name) < 0)
return true;
else
return false;
}
SalesRecord_Array read_records(ifstream& in, int &n)
{
in >> n;
if (n < 1 || in.fail())
return NULL;
while (in.get() != '\n');
SalesRecord_Array records;
records = new SalesRecord[n];
if (records == NULL)
{ cout << "\aCan not allocate memory!";
exit(1);
}
int i;
for(i = 0; in.good() && !in.eof() && i < n; i++)
{ records[i].read(in);
}
return records;
}
void calc_records(SalesRecord_Array records, int n)
{ int i;
for(i = 0; i < n; i++)
{ records[i].calc_commission();
}
}
void write_records(SalesRecord_Array records, int n)
{ char outfilename[MAX_FILE_NAME + 1];
ofstream out;
cout << "\n\nI need the output file name." << endl;
open_output(out, outfilename);
if (out.good())
{ out << n << endl;
int i;
for(i = 0; i < n; i++)
{ records[i].write(out);
}
out.close();
}
else
{ cout << "\a\nUnable to save data!" << endl;
}
}
他提供的txt文件的内容
3
4541
Hitt, Teresa
500
6666
Addams, Wednesday
1000
2121
Jones, Mary
389
他的sort.h的内容
#ifndef SORT_H
#define SORT_H
//A generic sorting function.
template<class T>
void sort(T a[], int number_used);
//Precondition: number_used <= declared size of the array a.
//The array elements a[0] through a[number_used - 1] have values.
//Postcondition: The values of a[0] through a[number_used - 1] have
//been rearranged so that a[0] <= a[1] <= ... <= a[number_used - 1].
template<class T>
void swap_values(T& variable1, T& variable2);
//Interchanges the values of variable1 and variable2.
template<class T>
int index_of_smallest(const T a[], int start_index, int number_used);
//Precondition: 0 <= start_index < number_used. Array elements have values.
//Returns the index i such that a[i] is the smallest of the values
//a[start_index], a[star_index + 1], ..., a[number_used - 1].
template<class T>
void sort(T a[], int number_used)
{
int index_of_next_smallest;
for (int index = 0; index < number_used - 1; index++)
{//Place the correct value in a[index]:
index_of_next_smallest =
index_of_smallest(a, index, number_used);
swap_values(a[index], a[index_of_next_smallest]);
//a[0] <= a[1] <=...<= a[index] are the smallest of the original array
//elements. The rest of the elements are in the remaining positions.
}
}
template<class T>
void swap_values(T& variable1, T& variable2)
{
T temp;
temp = variable1;
variable1 = variable2;
variable2 = temp;
}
template<class T>
int index_of_smallest(const T a[], int start_index, int number_used)
{
T min = a[start_index];
int index_of_min = start_index;
for (int index = start_index + 1; index < number_used; index++)
if (a[index] < min)
{
min = a[index];
index_of_min = index;
//min is the smallest of a[start_index] through a[index]
}
return index_of_min;
}
#endif
它在教学视频中按预期工作，但在我尝试过的两个系统上没有。
答案 0 :(得分：0)
道歉。问题出现在提供的txt文件中。在我的沮丧中，我不小心添加了一个空白的最后一行，这也解决了这个问题。
我猜测for（）挂在while (in.get() != '\n')