从文本文件读取到类中的对象向量 - 在另一个 txt 文件中写入

Question

I have changed the code, now the program reads teh file form students.txt correctly, but still calculated from user input instead of students.txt
#include #include #include #include #include #include #include #include

using namespace std;

//Declaring class Student   

class Student
{
private:

  string newName;
  int newScore1;
  int newScore2;
  int newScore3;
  float newFinal;

public:
  // No argument constructors
  Student ()

 {
  newName     = " ";
  newScore1   = 0;
  newScore2   = 0;
  newScore3   = 0;
  newFinal    = 0.00;

 }
 //all arguements constructors
 Student (string name, int score1, int score2, int score3, float final)

 {
 newName     = name;
 newScore1   = score1;
 newScore2   = score2;
 newScore3   = score3;
 newFinal      = final;
 } 
 //getters
 string getName() const
 {
  return newName;
 }
 int getScore1() const
 {
 return newScore1;
 }
 int getScore2()const
 {
 return newScore2;
 }
 int getScore3()const
 {
 return newScore3;
 }

 float getFinal () const
 {
  return newFinal;
 }

 //Setters
 void setName(string name)
 {
  newName = name;
 }
 void setScore1(int score1)
 {
 newScore1=score1;
 }
 void setScore2(int score2)
 {
  newScore2=score2;
 }
 void setScore3 (int score3)
 {
 newScore3 = score3;
 }

 void setFinal (float final)
 {
    newFinal = final;
 }


};
//asks for number of students, 
// function asks for input to fill in vector
//sorts the inputs to get max 2 scores out of 3 
//puts the data in a vector of class Student
//Sends data to a text file students.txt
 void fillvector(vector <Student>& newMyClass)

{
 string name;
 float score1;
 float score2;
 float score3;
 float final;
 float tmp;
 cout << "Please enter the number of Students: " << endl;
 int classSize;
 cin >> classSize;
 for (int i = 0; i < classSize; i ++)
   {
   cout << "Enter Student's name" << endl;
   cin >> name;
   cout << "Enter Student's Score 1" << endl;
   cin >> score1;
   cout << "Enter Student's Score 2" << endl;
   cin >> score2;
   cout << "Enter Student's Score 3" << endl;
   cin >> score3;
   if(score1>score2)
     {
      float tmp = score1;
      score1 = score2;
      score2 = tmp;
     }
   if(score1>score3)
     {
     float tmp = score1;
     score1=score3;
     score3 = tmp;
     }
   if(score2>score3)
    {
     float tmp = score2;
     score2=score3;
     score3=tmp;
    }

  final = (score2+score3)/2;

  Student newStudent (name, score1, score2, score3, final);
  newMyClass.push_back(newStudent);
  cout << endl;

  ofstream myfile;
  myfile.open ("students.txt", std::ofstream::out |std::ofstream::app );
  myfile << name<< setw(5)<< score1<< setw(5)<<score2<<setw(5)  <<score3<<setw(5)<<final<<setw(5)<<endl;
  myfile.close();
  cout << "Copied to students.txt" << endl;


   }
    cout << endl;
}
//reads data from textfile students.txt
//calculated teh minimum scores and maximum scores
//sends the minimum and maximum scores to text file Results.txt
void readToVector(vector <Student>& newMyClass)

{
    string name;
float score1;
float score2;
float score3;
float finalScore;
Student newStudent (name, score1, score2, score3, finalScore);
unsigned int size = newMyClass.size();
ifstream fin("students.txt");
if (fin.is_open())
  {cout << "File open" << endl;
    while(fin >> name >> score1 >> score2 >> score3 >> finalScore)
      {
    newStudent.setName(name);
    newStudent.setScore1(score1);
    newStudent.setScore2(score2);
    newStudent.setScore3(score3);
    newStudent.setFinal(finalScore);
    newMyClass.push_back(newStudent);
    //cout << newStudent.getName() << newStudent.getFinal() << endl;

      }
     fin.close();
    cout << endl;
    Student studWMaxScore  = newMyClass[0];
    float maxscore = studWMaxScore.getFinal();

for (unsigned int i =0; i < size; i++) 
{
    if (maxscore < newMyClass[i].getFinal())
  { 
   maxscore = newMyClass[i].getFinal();
   studWMaxScore = newMyClass[i];

  }

}
cout << "Maximum Score is " << maxscore << endl;
  ofstream myfile;
   myfile.open ("Result.txt", std::ofstream::out  );
   myfile << "Maximum Score" << endl;
   myfile << maxscore << endl;
   myfile << "Name of the student with maximum score is " <<  endl;
   myfile << studWMaxScore.getName() << endl <<  endl; 
   // myfile.close();
   cout << "Copied to Results.txt" << endl; 

Student stuWMinScore = newMyClass[0];
float minscore = stuWMinScore.getFinal();
for (unsigned int i =0; i < size; i++)
{
  if (minscore > newMyClass[i].getFinal())
    {
      minscore = newMyClass[i].getFinal();
      stuWMinScore = newMyClass[i];

    }   
}
cout << "Minimum Score is " << minscore << endl; 
// ofstream myfile;
//  myfile.open ("Result.txt", std::ofstream::out );
 myfile << "Mimimum Score" << endl;
myfile << minscore << endl;
myfile << "Name of the student with minimum score is " <<  endl;
myfile << stuWMinScore.getName() << endl <<  endl;
//  myfile.close();
cout << "Copied to Results.txt" << endl;
  }
else
  cout << "file in not open" << '\n';

}


//prints out the name and scores of each student
void printVector (const vector<Student>& newMyClass)

{
unsigned int size = newMyClass.size();
for (unsigned int i =0; i < size; i++)

  {
cout << "Student name is: "<< newMyClass[i].getName() << endl;
cout << "Student Score 1 is "<< newMyClass[i].getScore1()<< endl;
cout << "Student Score 2 is "<< newMyClass[i].getScore2()<< endl;
cout << "Student Score 3 is "<< newMyClass[i].getScore3()<< endl;
cout << "Student Final Score is " << newMyClass[i].getFinal() << endl;
cout << endl; 
  }

}




int main ()

{
vector <Student> myClass;
fillvector (myClass);
readToVector(myClass);
    printVector(myClass); 
}

Answer 1

Core of bug looks to be right here:

while(fin >> name >> score1 >> score2 >> score3 >> finalScore)
{
    newStudent.setName(name);
    newStudent.setScore1(score1);
    newStudent.setScore2(score2);
    newStudent.setScore3(score3);
    newStudent.setFinal(finalScore);
}
fin.close();
newMyClass.push_back(newStudent); 

Once the indentation is fixed, it's easy to see that newStudent is only pushed into the vector after the file has been completely read. OP should be getting the last student into the vector, but none of the others. Since OP probably wants all of the students in the file in the vector,

while(fin >> name >> score1 >> score2 >> score3 >> finalScore)
{
    newStudent.setName(name);
    newStudent.setScore1(score1);
    newStudent.setScore2(score2);
    newStudent.setScore3(score3);
    newStudent.setFinal(finalScore);
    newMyClass.push_back(newStudent); <- moved push_back to here
}
fin.close(); <- probably not necessary

Can't verify the rest of the code because there doesn't seem to be a definition or assignment of size --Crom only knows if those for loops are covering the correct ground--or the validity of the input because there is no provided input file. OP may be reading exactly nothing if the parsing rules are wrong. Debugger would figure that out much faster than another Stack Overflow post. (OP has since addressed this)

New stuff.

I don't see why the input doesn't parse either. First make sure the file is encoded as ASCII text. I do not know what tools you have to do this on your computer. I use a hex editor, lets you see the file in byte values rather than characters, to see if the characters are not matching their expected ASCII values. A text editor may be converting for you and hiding the differences.

For example, often a UTF-8 encoded file will look exactly the same as an ASCII file except for a bit of binary at the beginning marking informing the reader program that it is a UTF-8 file and may contain non-ASCII.

If it isn't, there's the problem. Re-save the file as an ASCII file. If it is an ASCII file, time to minimize. Write a small program that does nothing but open the file, read it token by token, and see which token fails to parse. Something like this:

int main()
{
    ifstream fin("students.txt");
    if (fin.is_open())
    {
        int line = 0;

        while(true) // loop forever
        {
            line++;
            if (!fin >> name)
            {
                std::cout << "Could not read name on line " << line << std::endl;
                break; // exit loop
            }
            if (!fin >> score1)
            {
                std::cout << "Could not read score1 on line " << line << std::endl;
                break;
            }
            if (!fin >> score2)
            {
                std::cout << "Could not read score2 on line " << line << std::endl;
                break;
            }
            if (!fin >> score3)
            {
                std::cout << "Could not read score3 on line " << line << std::endl;
                break;
            }
            if (!fin >> finalScore)
            {
                std::cout << "Could not read finalScore on line " << line << std::endl;
                break;
            }
        }
    }
    else
    {
       std::cout << "Could not open file" << std::endl;
    }
}

Once you know where the file fails, you are in great position to ask a new question. This one is sprawling a bit too much.