C++的平均值，最大值和最小值分配

Question

我的問題在於最終函數接近尾聲，程序從大約25個名稱的填充中抽取，每個名稱各有5個等級。平均數和最大數平穩運行，但似乎無法確定最低限度。我設法讓它取得幾個名字，但程序崩潰。任何人都可以幫助我理解我在此忽略的內容嗎？謝謝，麻煩您了。

如果將它插入編譯器中，min函數位於200-250行之間，並且使用簡單的txt文件從中提取名稱和等級。當等級小於50嘗試建立與儘可能多的警告開啓儘可能

// Headers 
#include <iostream>  // cout, cin 
#include <cstdlib>  // exit() 
#include <string>  // strings 
#include <fstream>  // file processing 
#include <iomanip>  // stream manipulation 
using namespace std; 

// Global variables 
const int MAX_STUDENTS = 25; // We will not process more than 25 students even if the file contains more 
const int MAX_GRADES = 5;  // Each student has exactly 5 grades 
const string FILENAME = "NamesGrades.txt"; // The name of the file that you will read 

// Function declarations 
int loadStudentNamesGrades(string students[], int grades[][MAX_GRADES], string fileName, int maxStudents); 
void displayAverages(string students[], int grades[][MAX_GRADES], int studentCount); 
void displayMax(string students[], int grades[][MAX_GRADES], int studentCount); 
void displayMin(string students[], int grades[][MAX_GRADES], int studentCount); 
string getLetterGrade(double grade); 
int getLongestNameLength(string students[], int studentCount); 

int main() 
{ 
    int studentCount = 0;     // You need one to keep up with the actual number of students 
    int grades[MAX_STUDENTS][MAX_GRADES]; // You need a two dimensional arry for the grades of the students 
    string students[MAX_STUDENTS];   // You need and array of strings for the student names 
    char choice;       // You need a variable to hold the choice of the user for the menu 

    // Get students and grades 
    studentCount = loadStudentNamesGrades(students, grades, FILENAME, MAX_STUDENTS); 

    // Loop until user says to quit (Do loop suggested) 
    do 
    { 
     // present menu and get user's choice 
     cout << "\nGrade Report Program\n\n"; 
     cout << "\t1. Display Average Grade\n"; 
     cout << "\t2. Display Maximum Grade\n"; 
     cout << "\t3. Display Minimum Grade\n"; 
     cout << "\t4. Quit Program\n"; 
     cout << "\nEnter your choice (1-4): "; 
     cin >> choice; 

     // Process the choice 
     switch(choice) 
     { 
      case '1':  // Average 
       displayAverages(students, grades, studentCount); 
       break; 
      case '2':  // Maximum 
       displayMax(students, grades, studentCount); 
       break; 
      case '3':  // Minimum 
       displayMin(students, grades, studentCount); 
       break; 
      case '4':  // Quit 
       break; 
      default: 
       cout << "Invalid option.\n\n"; 

     } 
     if(choice != '4') 
     { 
      cout << endl; 
      system("PAUSE"); 
      system("CLS"); 
     } 

    } while(choice != '4');  

    cout << endl; 

    return 0; 
} 

/*********************************************************** 
loadStudentNameGrades opens and read fileName. It will read in two strings, concatenate them, and then save 
to the students array. It then reads five integers and save each to the grades array. The function will return 
the actual number of student/grade combinations read 
PARAM: students is an array of strings that can hold up ot maxStudents values 
     grades is a two dimensional array for holding the grades of each student 
     fileName is the name of the file that will be opened and read 
     maxStudents is the maximum number of students that we will read from the file 
PRE: students[] is large enough to contain up to maxStudents elements 
     grades[] is large enough ot contain up to maxStudents elements 
POST: students[] contains the names of up to maxStudents 
     grades[][] contains the grades for up to maxStudents 
     The number of student/grade combinations actually read from the file is returned. This value can range 
     between 0 <= numStudents <= maxStudents 
NOTE: students[] and grades[] are meant to be parralel arrays. students[0] and grades[0] are the same student  
************************************************************/ 
// Check 16:15 
int loadStudentNamesGrades(string students[], int grades[][MAX_GRADES], string fileName, int maxStudents) 
{ 
    ifstream inFile; // input file stream 
    string studentsName, letterGrade; // Name of the student and grade character (char) 
    int numStudents = 0; // number of students actually read 


    // Open the file 
    inFile.open(fileName.c_str()); 
    if(inFile.fail()) 
    { 
     cout << "Could not open file" << endl; 
     system("PAUSE"); 
     exit(1); 
    } 

    for(int i = 0; i < maxStudents && (inFile >> studentsName >> letterGrade); i++, numStudents++) 

    { 
     for(int j = 0; j < MAX_GRADES; j++) 
     { 
      inFile >> grades[i][j]; 
     } 
     students[i] = studentsName + " " + letterGrade; 
    } 

    inFile.close(); 

    return numStudents; 
} 

/*********************************************************** 
displayAverages calculates the average of each student and displays the 
students name, average, and letter grade of the average in a table 
PARAM: students[] is an array of strings that contains the names of studentCount students 
     grades[] is an array of integers that contains the grades of studentCount students 
     studentCount contains the value of the number of elements in the students[] and grades[] arrays 
PRE: students[] and grades[] contain values for studentCount elements 
POST: table of student names, averages, and letter grades is displayed 
************************************************************/ 
// Check 16:15 
void displayAverages(string students[], int grades[][MAX_GRADES], int studentCount) 
{ 
    double average;  // Average grades of students 
    int total;   // total of all grades (accumulator) 
    int maxLength = getLongestNameLength(students,studentCount); 

    cout << setprecision(1) << fixed << showpoint; 
    // Setup table header 
    cout << "\n\nGrade Averages\n"; 
    cout << setw(maxLength + 1) << left << "Name" << setw(4) << right << "Average" << setw(6) << "Grade" << endl; 
    for(int i = 0; i < studentCount; i++) 
    { 
     cout << setw(maxLength + 1) << left << students[i]; 
     total = 0; 


     for(int j = 0; j < MAX_GRADES; j++) 
     { 
      total += grades [i][j]; 
     } 
     average = (double)total/MAX_GRADES; 
     cout << setw(7) << right << average << setw(6) << getLetterGrade(average) << endl; 
    }  
} 

/*********************************************************** 
displayMax calculates the maximum grade of each student and displays the 
students name, maximum grade, and letter grade of the maximum grade in a table 
PARAM: students[] is an array of strings that contains the names of studentCount students 
     grades[] is an array of integers that contains the grades of studentCount students 
     studentCount contains the value of the number of elements in the students[] and grades[] arrays 
PRE: students[] and grades[] contain values for studentCount elements 
POST: table of student names, maximum grades, and letter grades is displayed 
************************************************************/ 
// Check 16:15 
void displayMax(string students[], int grades[][MAX_GRADES], int studentCount) 
{ 
    int maxGrade; 
    int maxLength = getLongestNameLength(students,studentCount); 

    cout << "\n\nGrade Maximums\n"; 
    cout << setw(maxLength + 1) << left << "Student" << setw(4) << right << "Max" << setw(6) << "Grade" << endl; 

    for(int i = 0; i < studentCount; i++) 
    { 
     cout << setw(maxLength + 1) << left << students[i]; 
     maxGrade = 0; 
     for(int j = 0; j < MAX_GRADES; j++) 
     { 
      if(maxGrade < grades [i][j]) maxGrade = grades [i][j]; 
     } 
     cout << setw(4) << right << maxGrade << setw(6) << getLetterGrade(maxGrade) << endl; 
    } 
} 


/*********************************************************** 
displayMin calculates the minimum grade of each student and displays the 
students name, minimum grade, and letter grade of the minimum grade in a table 
PARAM: students[] is an array of strings that contains the names of studentCount students 
     grades[] is an array of integers that contains the grades of studentCount students 
     studentCount contains the value of the number of elements in the students[] and grades[] arrays 
PRE: students[] and grades[] contain values for studentCount elements 
POST: table of student names, minimum grades, and letter grades is displayed 
************************************************************/ 
/* Notes: 
Program seems to pull 2 names and freeze on the third. Unsure as to why? 
Assigns Leslie Carter 36C and code seems to break down afterwords. 
Issue is undetected any where else and seems to be isolated in this function. 
*/ 

void displayMin(string students[], int grades[][MAX_GRADES], int studentCount) 
{ 
    int minGrade; 
    int maxLength = getLongestNameLength(students,studentCount); 

    cout << "\n\nGrade Minimums\n"; 
    cout << setw(maxLength + 1) << left << "Student" << setw(4) << right << "Min" << setw(6) << "Grade" << endl; 

    for(int i = 0; i < studentCount; i++)  // > is null result, < is result 
    { 
     cout << setw(maxLength + 1) << left << students[i]; 
     minGrade = 101;             // Produced a result in the correct direction 
     for(int j = 0; j < MAX_GRADES; j++) 
     { 
      if(minGrade > grades [i][j]) minGrade = grades [i][j];  // Produced a result in the correct direction 
     } 
     cout << setw(4) << right << minGrade << setw(6) << getLetterGrade(minGrade) << endl; 
    } 
} 

/*********************************************************** 
getLetterGrade converts a numerical grade to a letter grade 
PARAM: grade is the numerical grade to convert. Expected range is 0 <= grade <= 100 
PRE: grade contains a value in the correct range 
POST: The corresponding letter grade of the numerical grade is returned 
************************************************************/ 
// Check 16:15 
string getLetterGrade(double grade) 
{ 
    if(grade > 90) 
     return "A"; 
    else if(grade > 80) 
     return "B"; 
    else if(grade > 70) 
     return "C"; 
    else if(grade > 60) 
     return "D"; 
    else if(grade > 50) 
     return "F"; 
} 

/*********************************************************** 
getLongestNameLength returns the length of the longest string from a list of strings 
PARAM: students[] is an array of strings that contains the name of students 
     studentCount is the size of the students[] array 
PRE: students[] contains studentCount names 
POST: The length of the longest string in students[] is returned 
************************************************************/ 
// Check 16:15 
int getLongestNameLength(string students[], int studentCount) 
{ 
    int maxLength = 0; 
    for(int i = 0; i < studentCount; i++) 
    { 
     if(students[i].length() > maxLength) maxLength = students[i].length(); 
    } 
    return maxLength; 
} 

Answer 1

你getLetterGrade函數不返回任何東西。 -Wall本來會警告你這個錯誤。