c++输入数据读取不正确

Question

我在读取输入文件时遇到问题。该程序可以完美地读取输入文件并且运行良好，除了它会读取文档中最后一个人的名字两次。

这是程序输出的一部分，两次显示 hooper、grace name。感谢收看

****Input file lab10data1.txt is open for reading.
Number of student records read = 17
The following student(s) have the highest score
 Einstein, Albert
List of All the Students in the class
 Student Name          Test Score     Grade
 ------------------------------------------
 Fibonacci, Leonardo        63         D
      Huffman, David        79         C
        Augusta, Ada        91         A
 Goldbach, Christian        81         B
          Venn, John       100         A
      Church, Alonzo        72         C
    Einstein, Albert       105         F
      Fermat, Pierre        84         B
     Kruskal, Joseph        66         D
       Cantor, Georg        67         D
        Turing, Alan        85         B
      Chebysheva, PL       100         A
  DeMorgan, Augustus        79         C
   Karnaugh, Maurice        72         C
    Babbage, Charles        98         A
       Hooper, Grace        95         A
       Hooper, Grace        95         A // RIGHT HERE it reads grace twice

这是代码

    #include<iostream>
    #include<fstream>
    #include<string>
    #include<iomanip>**


using namespace std;

struct StudentType
{
    string studentName;
    int testScore;//Between 0 and 100
    char grade;
};

void PrintNameHeader(ostream& out);
bool OpenInputFile(ifstream& inFile, string& infilename ); //OPEN input file
void Pause();// Pause
void ReadStudentData(ifstream& infile, StudentType student[], int& );// Read student infp including first and last name and test score
void AssignGrades(StudentType student[], int);//assign grades to each student
int HighestScore(const StudentType student[], int );//Get the highest scores
void PrintNamesWithHighestScore(const StudentType student[], int);//Print name/s with highest Scores
void DisplayAllStudents(const StudentType student[], int);//Display all students
void GetLowHighRangeValues(const StudentType student[], int, int& , int&);//for example a student types 50 100 , it will get all students within that range
void DisplayStudentsInRange(const StudentType student[], int, int, int);// display students in that range
void SortStudentsByName(StudentType student[], int);// sort students by name
void SortStudentsByScore(StudentType student[], int);// sort students by test score highest to lowest
void FormatNameScoreGrade(ostream& out);


const int NUM_STUDENTS = 20;

int main()
{
    ifstream infile;
    string inFilename;
    StudentType student[NUM_STUDENTS];
    int numStudents = 0;

    PrintNameHeader(cout);

    if(!OpenInputFile(infile,inFilename)) return 1;

    ReadStudentData(infile, student, numStudents);
    infile.close();

    AssignGrades(student, numStudents);

    PrintNamesWithHighestScore(student, numStudents);

    cout <<"List of All the Students in the class" << endl;
    DisplayAllStudents(student, numStudents);

    Pause();//Pause

    int lownum, highnum;
    char answer;

    do {

        GetLowHighRangeValues(student, numStudents, lownum, highnum);

        DisplayStudentsInRange(student, numStudents, 70, 90);
        cout <<"Do you want to see another range of scores [y/n]?";
        cin >> answer;
    } while( answer == 'y' || answer == 'Y');

    SortStudentsByName(student, numStudents);
    Pause();//Pause

    SortStudentsByScore(student, numStudents);

    return 0;
}

//Function definitions

void PrintNameHeader(ostream& out)
{
    //Display name header on screen


}

void FormatNameScoreGrade(ostream& out)
{
    out  << setw(10) << " Student Name" << setw(20) <<"Test Score" << setw(10) <<"Grade" << endl;
    out <<" ------------------------------------------" << endl;
}

bool OpenInputFile(ifstream& inFile, string& infilename) 
{
    cout << "Enter the name of the .txt file that you want to open for input.\n";
    cout << "Do not put spaces in the file name : ";
    cin >> infilename;
    cout << endl;

    inFile.open(infilename.c_str());
    if (inFile.fail())
    {
        cout << "Sorry, the input file " << infilename <<" was not found"<< endl;\
            return false;
    }

    cout << "Input file " << infilename << " is open for reading.\n\n";
    return true;
}

void Pause()
{
    cout << endl;
    cin.ignore(80, '\n');
    cout<<"Please hit the enter key to continue...\n";
    cin.get();
}

void ReadStudentData(ifstream& infile, StudentType student[], int& numStudents)
{
    string firstName, lastName;
    int testScore;
    int count = 0;

    while(infile)
    {
        infile >> firstName >> lastName >> testScore;
        student[count].studentName = lastName + ", " + firstName;
        student[count].testScore = testScore;
        count++;
    }

    numStudents = count;
    cout << "Number of student records read = " << numStudents << endl;
}

void AssignGrades(StudentType student[], int numStudents)
{

    int testscore;
    char grade;

    for(int i = 0; i < numStudents; i++)
    {
        testscore = student[i].testScore;

        if(testscore >= 90 && testscore <=100)
            grade = 'A';
        else if(testscore >= 80 && testscore <90)
            grade = 'B';
        else if(testscore >= 70 && testscore <80)
            grade = 'C';
        else if(testscore >= 60 && testscore <70)
            grade = 'D';
        else
            grade = 'F';

        student[i].grade = grade;
    }
}

int HighestScore(const StudentType student[], int numStudents)
{
    int highest = student[0].testScore;

    for(int i = 1; i < numStudents; i++)
    {
        if(highest < student[i].testScore) highest = student[i].testScore;
    }

    return highest;
}

void PrintNamesWithHighestScore(const StudentType student[], int numStudents)
{
    int highest = HighestScore(student, numStudents);
    cout << endl << "The following student(s) have the highest score" << endl << endl;
    for(int i = 0; i < numStudents; i++)
    {
        if (student[i].testScore == highest)
        {
            cout << " " << student[i].studentName;
        }
    }

    cout << endl;
}

void DisplayAllStudents(const StudentType student[], int numStudents)
{
    cout << endl;

    FormatNameScoreGrade(cout);

    for(int i = 0; i < numStudents; i++)
    {

        cout << setw(20) << student[i].studentName << setw(10) << student[i].testScore << setw(10) << student[i].grade << endl;
    }

    cout << endl;
}

void GetLowHighRangeValues(const StudentType student[], int numStudents, int& lowRange, int& highRange)
{
    int lowest = student[0].testScore;

    for(int i = 1; i < numStudents; i++)
    {
        if(lowest > student[i].testScore) lowest = student[i].testScore;
    }

    lowRange = lowest;
    highRange = HighestScore(student, numStudents);
}

void DisplayStudentsInRange(const StudentType student[], int numStudents, int lownum, int highnum)
{
    cout <<"Enter two vales for the range of scores you want to look at: ";
    cin >> lownum >> highnum;






    cout << endl << "List of students with scores in the range " << lownum << " to " << highnum << endl << endl;
    FormatNameScoreGrade(cout);


    for(int i = 0; i < numStudents; i++)
    {
        if(student[i].testScore >= lownum && student[i].testScore <= highnum)
        {

            cout << setw(20) << student[i].studentName << setw(10) << student[i].testScore << setw(10) << student[i].grade << endl;
        }
    }
    cout << endl;
}

void SortStudentsByName(StudentType student[], int numStudents)
{
    StudentType temp;

    for(int i = 0;i < numStudents - 1;i++)
    {
        for(int j = i + 1; j < numStudents;j++)
        {
            if(student[i].studentName > student[j].studentName)
            {
                temp = student[i];
                student[i] = student[j];
                student[j] = temp;
            }
        }
    }

    cout << endl;
    cout << "List of Students sorted by Name" << endl;
    DisplayAllStudents(student, numStudents);
}

void SortStudentsByScore(StudentType student[], int numStudents)
{
    StudentType temp;

    for(int i = 0;i < numStudents - 1;i++)
    {
        for(int j = i + 1; j < numStudents;j++)
        {
            if(student[i].testScore < student[j].testScore)
            {
                temp = student[i];
                student[i] = student[j];
                student[j] = temp;
            }
        }
    }

    cout <<"List of Students sorted by Score" << endl;
    DisplayAllStudents(student, numStudents);
}

Answer 1

改变:

while (infile)
{
    infile >> firstName >> lastName >> testScore;
// ...

到

while (infile >> firstName >> lastName >> testScore)
{
// ...

以便在检查流之前执行读取。