我正在编写代码来输入学生和成绩对象，对它们进行排序，计算平均gpa，然后将它们输出到文件中。我当前的问题是我的学生对象的输出是在我对它们进行排序并打印之后给出的，但是一旦我这样做，代码似乎就不会离开循环了。我有一个打印功能，我正在通过一个流。从调试开始，我知道out ofstream对象会读取所有内容，但它似乎会冻结，而不会输出任何其他内容。有人告诉我，如果我错误地通过引用，或者我是否需要做其他事情？编译器没有经过的错误标记在代码中。
很抱歉，所以有关更多信息，请参阅下面的内容，了解运行的内容
注意＆＃34;如何通过它＆＃34;只显示一次。我知道打开文件和输出不是问题，因为它确实输出了正确的东西。此外，为了纠正，编译器实际编译一切都很好。它在运行时终端停止运行，不再输出。
#include <vector>
#include <algorithm>
#include <iostream>
#include <sstream>
#include <iomanip>
#include <fstream>
#include <string>
#include "Grade.h"
#include "Student.h"
using namespace std;
const double A_NUM = 4.0, B_NUM = 3.0, C_NUM = 2.0, D_NUM = 1.0, E_NUM = 0.0, B_PLUSSNUM = 3.4, C_PLUSSNUM = 2.4, D_PLUSSNUM = 1.4;
const double A_MINUSNUM = 3.7, B_MINUSNUM = 2.7, C_MINUSNUM = 1.7, D_MINUSNUM = 0.7;
const int FIRST_INDEX= 0;
const int START_NUM = 0;
const int LESS_ONE = 1, ABOVE_ONE = 1;
const int START_GRADE = 0;
void calcgrades(vector<Grade>& grades)//function that calculates gpa based on letter grades
{
const string A = "A", A_MINUS = "A-", B_PLUSS = "B+", B = "B", B_MINUS = "B-", C_PLUSS = "C+", C = "C", C_MINUS = "C-", D_PLUSS = "D+", D = "D", D_MINUS = "D-", E = "E";
int counter = START_NUM;//used to keep track of current student and current total grade
double current_grade = START_NUM;
for(int i = 0; i < grades.size();i++)
{
//while loop to get the student's current total grade if the next student id is different than the first one.
while(i < grades.size()-LESS_ONE && grades[i].getid() == grades[i+ABOVE_ONE].getid())
{
if (grades[i].getgrade() == A)
{
current_grade == A_NUM + current_grade;
}
if (grades[i].getgrade() == B)
{
current_grade == B_NUM + current_grade;
}
if (grades[i].getgrade() == C)
{
current_grade == C_NUM + current_grade;
}
if (grades[i].getgrade() == D)
{
current_grade == D_NUM + current_grade;
}
if (grades[i].getgrade() == E)
{
current_grade == E_NUM + current_grade;
}
if (grades[i].getgrade() == B_PLUSS)
{
current_grade == B_PLUSSNUM + current_grade;
}
if (grades[i].getgrade() == C_PLUSS)
{
current_grade == C_PLUSSNUM + current_grade;
}
if (grades[i].getgrade() == D_PLUSS)
{
current_grade == D_PLUSSNUM + current_grade;
}
if (grades[i].getgrade() == A_MINUS)
{
current_grade == A_MINUSNUM + current_grade;
}
if (grades[i].getgrade() == B_MINUS)
{
current_grade = B_MINUSNUM + current_grade;
}
if (grades[i].getgrade() == C_MINUS)
{
current_grade = C_MINUSNUM + current_grade;
}
if (grades[i].getgrade() == D_MINUS)
{
current_grade = D_MINUSNUM + current_grade;
}
}
if (grades[i+ABOVE_ONE].getid() != grades[i].getid() || i == grades.size()-LESS_ONE)
{
//computes the average if the currentid is not equal to the nextid
double avggpa = current_grade/counter;
grades[i].newgpa(avggpa);
counter = START_NUM;//resets counter for a new student to get his gpa
}
counter++;
}
}
int main(int argc, char* argv[])
{
string student_file, grades_file, idnum, name, address, pnum, course, gletter;
//creates student and grade objects from respective classes
vector<Student> students;
vector<Grade> grades;
student_file = argv[1];
//reads in information from file to import into student objects
ifstream sfile;
sfile.open(student_file);
while(getline(sfile, idnum))//gets the student information from student file
{
getline(sfile, name);
getline(sfile, address);
getline(sfile, pnum);
//creates student objects to import info. into, and inserts into students vector
Student s(idnum, name, address, pnum);
students.push_back(s);
}
sfile.close();
//opens information from the grade file
grades_file = argv[2];
//reads from file to import into grades objects
ifstream gfile;
gfile.open(grades_file);
//gets the grade information from the grades file
while(getline(gfile, course))
{
getline(gfile, idnum);
getline(gfile, gletter);
//creates grade objects to import info, and inserts into grades vector
Grade g(course, idnum, gletter, START_GRADE);
grades.push_back(g);
}
gfile.close();
//reads the query file
string query_file;
query_file = argv[3];
ifstream qfile;
qfile.open(query_file);
//reads from query file
//creates vector to store each student number
vector<string> query_nums;
string incheck;
while(getline(qfile, incheck))
{
query_nums.push_back(incheck);
}
qfile.close();
//sorts the information for the students
sort(students.begin(), students.end());
//sorts the information for the grades
sort(grades.begin(), grades.end());
ofstream outtxt;
string out_file = argv[4];
outtxt.open(out_file);
//outputs the student information, sorted now.
for(int i = 0; i < students.size();i++)
{
students[i].print(outtxt);
outtxt << "got through it";
}
//compiler did not get past here!
outtxt << "We're here!";
//outputs the grades with student id's, now sorted
for (int i = 0; i < grades.size(); i++)
{
grades[i].print(outtxt);
outtxt << "\n\n" << "some output!";
}
//calculates the average gpa for every student
calcgrades(grades);
for(int i = 0; i < query_nums.size(); i++)//goes through each query number to check first
{
for (int j = 0; j < students.size(); j++)//after, goes through each student object
{
if (query_nums[i] == students[j].getid())
{
//finds the gpa in the grades class that matches the student id
for (int k = 0; k < grades.size(); k++)
{
if (grades[k].getid() == query_nums[i])//
{
//outputs the resulting id, avg gpa, and name of matching students
outtxt << grades[i].getid() << "\tthere is nothinghere" << grades[i].getgpa() << "\t" << students[i].getname();
}
}
}
}
}
outtxt.close();
return 0;
}
具有印刷功能的学生班
class Student
{
private:
string idnum;
string name;
string address;
string pnum;
public:
//defines constructor
Student(string idnum,string name,string address,string pnum);
//prints each student info
void print(ofstream& out);
string getname();
string getid();
bool operator < (Student s) const {
return idnum < s.idnum;
}
};
学生cpp文件
#include "Student.h"
#include <iostream>
#include <string>
#include <iomanip>
#include <fstream>
using namespace std;
//Student constructor, used to make student objects
Student::Student(string id,string nm,string add,string pnumber)
{
idnum = id;
name = nm;
address = add;
pnum = pnumber;
}
void Student::print(ofstream& out)
{
out << name << endl << idnum << endl << pnum << endl << address << endl;
}
string Student::getname()
{
//returns the student name
return name;
}
string Student::getid()
{
return idnum;
}
答案 0 :(得分：0)
在回答有关如何正确传递ofstream对象的问题时，您正确传递它。
那为什么它不起作用？从您的代码中可以观察到的内容，它应该可以正常工作。我建议在这些代码行中调试输出文件名：
ofstream outtxt;
string out_file = argv[4];
outtxt.open(out_file);
在调用open函数后检查ios :: fail标志，验证open函数是否成功。
打开后尝试这样的事情：
if (ios::fail)
cout << "fail";
我希望这会有所帮助。
已编辑：可能存在其他问题，但calcgrades（）函数在while循环之后的最后一次for循环迭代中对此if语句进行了访问冲突：
if (grades[i+ABOVE_ONE].getid() != grades[i].getid() || i == grades.size()-LESS_ONE)