試圖讀取文件

Question

試圖編寫需要讀取某些數據的程序。它不會打開文件並讀取數據。它似乎與getData功能有關。

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

using namespace std; 

const int NUM_STUDENTS = 20; 
const int NUM_GRADES = 5; 

struct StudentType { 
    string name; 
    int grades[NUM_GRADES]; 
    int average; 
    char letterGrade; 
}; 

void getData(StudentType students[]); 
void printGrades(StudentType students[]); 
void assignGrades(StudentType students[]); 
string convert(string name); 
float findHighest(StudentType students[]); 
void printHighest(StudentType students[]); 

int main() 
{ 
    StudentType students[20]; 

    getData(students); 
    printGrades(students); 

    return 0; 
} 

void getData(StudentType students[]) { 

    string name, filename; 
    ifstream fin; 

    cout << "Please Enter the file name: "; 
    cin >> filename; 
    fin.open(filename.c_str()); 

    while (!fin) { 
     cout <<"Could not open " << filename << ", please re-enter the filename" << endl; 
     cout << "Please Enter the file name: "; 
     cin >> filename; 
     fin.open(filename.c_str()); 
    } 

    for (int index = 0; index < NUM_STUDENTS; ++index) { 
     int total = 0; 
     getline(fin, name); 
     students[index].name = convert(name); 

     for (int i = 0; i <NUM_GRADES; ++i) { 
      fin >> students[index].grades[NUM_GRADES]; 
      fin.ignore(INT_MAX, '\n'); 
      total = total + students[index].grades[NUM_GRADES]; 
     } 
     students[index].average = static_cast<float>(total)/NUM_GRADES; 
    } 
    fin.close(); 
} 

string convert(string name) { 
    string s; 
    string:: size_type x; 
    x = name.find("."); 

    if (x != string::npos) { 
     ++x; 
    } 
    else { 
     x = name.find(" "); 
    } 

    s = name.substr(x+1, name.size()) + ", " + name.substr(0,x); 

    return s; 
} 

void printGrades(StudentType students[]) { 
    for (int index = 0; index < NUM_STUDENTS; ++index) { 
     cout << students[index].name; 
     cout << "  "; 

     for (int i = 0; i <NUM_GRADES; ++i) { 
      cout << students[NUM_STUDENTS].grades[NUM_GRADES]; 
      cout << " "; 
     } 
     cout << students[NUM_STUDENTS].average; 
    } 
} 

void assignGrades(StudentType students[]) { 
    for (int index = 0; index < NUM_STUDENTS; ++index) { 
     if (students[NUM_STUDENTS].average < 60) 
      students[NUM_STUDENTS].letterGrade = 'F'; 
     else if (students[NUM_STUDENTS].average < 70) 
      students[NUM_STUDENTS].letterGrade = 'D'; 
     else if (students[NUM_STUDENTS].average < 80) 
      students[NUM_STUDENTS].letterGrade = 'C'; 
     else if (students[NUM_STUDENTS].average < 90) 
      students[NUM_STUDENTS].letterGrade = 'B'; 
     else 
      students[NUM_STUDENTS].letterGrade = 'A'; 
    } 
} 

float findHighest(StudentType students[]) { 
    float highestAverage = 0; 
    for (int index = 0; index < NUM_STUDENTS; ++index) { 
     if (students[index].average > highestAverage) 
      highestAverage = students[index].average; 
    } 
    return highestAverage; 
} 

void printHighest(StudentType students[]) { 
    float highestAverage = findHighest(students); 
    cout << "The name(s) of the student(s) with the Highest average are "; 

    for (int index = 0; index < NUM_STUDENTS; ++index) { 
     if (students[index].average == highestAverage) 
      cout << students[index].name << " "; 
    } 
} 

Answer 1

這裏有一個清單：

1. 是否文件中存在？
2. 文件是否在正確的位置？
3. 嘗試用'/'替換路徑中的'\'。
4. 文件是否被鎖定？
5. 您是否有權限打開它？
6. 你能用more或less訪問文件嗎？
7. 如果文件名有空格，你是否在 名稱周圍放置雙引號？
8. 如果文件名有破折號' - '，是否在 雙引號中加上了名字？
9. 嘗試編寫一個臨時文件來查找默認目錄。