Question

我在修复这个无限循环时遇到了问题。我做了一些测试，所以我很确定循环不是在读取文件时。就在“printReportHeading（）;”之后是一个for循环。我很确定这是造成问题的原因。我该如何解决这个问题。是否与二维数组的初始化有关？

代码：

  int main(void)
   {
    FILE* fileIn;
    FILE* printFile;

    float average;

    char letterGrade;

    int wholeArray [MAX_STUDENTS][MAX_PROFILE],
            letterFreq[5];

   printInstructions();

    fileIn = fopen("input11.dat", "r");

    if(fileIn == NULL)
    {
            printf("\n\nFILE COULD NOT BE LOCATED\n\n");
    }
    else
    {
            printFile = fopen("upchurch.txt", "w");

            loadData(fileIn, wholeArray);

            printReportHeading();

            for(int row = 0; row < MAX_STUDENTS; row++)
            {
                    average = calcAverage(wholeArray);
                    letterGrade = determineLetter(average);
                    printLine(printFile, wholeArray, average, letterGrade);

                    switch(letterGrade)
                    {
                            case 'A':
                                    letterFreq[0]++;
                                    break;
                            case 'B':
                                    letterFreq[1]++;
                                    break;
                            case 'C':
                                    letterFreq[2]++;
                                    break;
                            case 'D':
                                    letterFreq[3]++;
                                    break;
                            default:
                                    letterFreq[4]++;
                                    break;
                    }
            }

            printHighScores(printFile, wholeArray);
            printLowScores(printFile, wholeArray);
            printAverageScores(printFile, wholeArray);
            fprintf(printFile, "---------------------------------------------\n");

            printHistogram(printFile, letterFreq);
    }

    return;
}


/******************************************************************************
 *Prints the instructions to the user*
******************************************************************************/
void printInstructions(void)
 {
    printf("=================================================================\n");
    printf("= This program takes up to 40 student's ID and five quiz grades =\n");
    printf("= then finds each students letter grade, average of each quiz,  =\n");
    printf("= highest and lowest grade of each quiz, and creates a          =\n");
    printf("= histogram of all of the students letter gradesa as a whole.   =\n");
    printf("=================================================================\n\n");

    return;
}
/******************************************************************************
 *Gets the data from the file for the user*
******************************************************************************/
int loadData(FILE* fileIn, int wholeArray[][MAX_PROFILE])
{
    for(int i = 0; i < MAX_STUDENTS; i++)
            for(int j = 0; j < MAX_PROFILE; j++)
            {
                    fscanf(fileIn, "%d", &wholeArray[i][j]);
            }

    return 0;
}
/******************************************************************************
 *Prints the report heading*
******************************************************************************/
void printReportHeading()
{
    printf("Student   Quiz 1   Quiz 2   Quiz 3   Quiz 4   Quiz 5   Average   Letter\n");

    return;
 }

/******************************************************************************
 *Calculates each student's average and letter grade*
******************************************************************************/
float calcAverage (int wholeArray[][MAX_PROFILE])
{
    int totalGrades = 0;

  for (int i = 1; i < MAX_PROFILE; i++)
  {
     totalGrades += *wholeArray[i];
  }


     return (totalGrades / 5.0f);
}
/******************************************************************************
 *Finds the letter grade*
******************************************************************************/
char determineLetter(float average)
{
    char letterGrade;

    if (average >= 90)
            letterGrade = 'A';
    else if (average >= 80)
            letterGrade = 'B';
    else if (average >= 70)
            letterGrade = 'C';
    else if (average >= 60)
            letterGrade = 'D';
    else
            letterGrade = 'F';

    return letterGrade;
}
/******************************************************************************
 Prints a line of students information
******************************************************************************/
void printLine(FILE* printFile, int wholeArray[][MAX_PROFILE], float average, char letterGrade)
{
    for(int i = 0; i <= MAX_STUDENTS; i++)
       for(int j = 0; j < MAX_PROFILE; j++)
       {
          fprintf(printFile, "%d", wholeArray[i][j]);
             if ((j = MAX_PROFILE))
             {
                printf("%3.2f", average);
                printf("%c", letterGrade);
                j = 0;
             }
       }
    fprintf(printFile, "---------------------------------------------------\n");

    return;
}

/******************************************************************************
 Find the high score of each quiz
******************************************************************************/
void printHighScores(FILE* printFile, int wholeArray[][MAX_PROFILE])
{
    int highestTest = 0;

    fprintf(printFile, "High ");

    for (int i = 1; i < MAX_PROFILE; i++)
    {
            for(int j = 0; j < MAX_STUDENTS; j++)
            {
                    if (highestTest < wholeArray[j][i])
                    {
                            highestTest = wholeArray[j][i];
                    }
            }

            fprintf(printFile, "%3d", highestTest);
    }
    return;
}

/******************************************************************************
 Finds the low score of each quiz
******************************************************************************/
void printLowScores(FILE* printFile, int wholeArray[][MAX_PROFILE])
{
    int lowestTest = 100;

    fprintf(printFile, "Low  ");

    for (int i = 1; i < MAX_PROFILE; i++)
    {
            for(int j = 0; j < MAX_STUDENTS; j++)
            {
                    if (lowestTest > wholeArray[j][i])
                    {
                            lowestTest = wholeArray[j][i];
                    }
            }

            fprintf(printFile, "%3d", lowestTest);
    }
    return;
} 

/******************************************************************************
 Finds the average score of each quiz
******************************************************************************/
void printAverageScores(FILE* printFile, int wholeArray[][MAX_PROFILE])
{
    float averageTest = 0.0;

    int i;

    fprintf(printFile, "Average   ");

    for (i = 1; i < MAX_PROFILE; i++)
    {
            for(int j = 0; j < MAX_STUDENTS; j++)
            {
                    averageTest += wholeArray[j][i];

            }
            averageTest = averageTest / i;

            fprintf(printFile, "%5.2f", averageTest);
    }
    return;
}

 /******************************************************************************
 Prints histogram of letter frequency
 ******************************************************************************/
void printHistogram(FILE* printFile, int letterFreq[5])
{
    for (int i = 0; i < 5; i++)
    {
            for (int j = 1; j <= letterFreq[i]; j++)
                    printf("*");
            printf("\n");
    }
    return;
}

Answer 1

在printLine中，您有：

if ((j = MAX_PROFILE))
{
    …
    j = 0;
}

这有两个问题。首先，j = MAX_PROFILE是一项任务，而非比较。它将j设置为MAX_PROFILE并计算为true，从而导致执行if的正文。

然后if的正文将j设置为零。这会导致内循环无限重复。

我怀疑你打算在打印学生档案的所有行后打印平均值和等级。在这种情况下，只需在j上的循环后打印它们，仍然在i的循环内。无需测试，也无需将j设置为零。

Answer 2

这可能不是您的错误的原因，但letterFreq永远不会被初始化，因此printHistogram会调用未定义的行为并最终打印出数十亿的“*”。对此的修复只是将数组成员初始化为0

letterFreq[5] = {0};

具有2d阵列的无限循环

2 个答案: