为什么我会收到分段错误错误？

Question

我收到一个分段错误，我不确定这意味着什么，找不到什么错误？ 微微是给这个错误， 这里是我的代码：

#include <stdio.h> 
#include <stdlib.h> 
#include <stdbool.h> 
#include <string.h> 
//Struct groups each line in the file 
struct gradesRecord 
    { 
     int iIndex;  // index on the file 
     int iStudentNUM; // 'Student' field 
     int iExamGrouped[3]; // 'Exam 1'..'Exam 3' fields 
     char cStudentAVG; // 'Grade' field 
    }; 
void printUnsortedStringFromFile(int amount, struct gradesRecord A[]); 
void printSortedStringFromFile(int amount, struct gradesRecord A[]); 
//bool binSearchNUM(int amount, int A[amount], int target,); 

int main() 
{ 
    FILE* spData = fopen("grades.csv", "r"); 
    int ch, number_of_lines = 0; 
    do 
    { 
     ch = fgetc(spData); 
     if (ch == '\n') 
      number_of_lines++; 
    } while (ch != EOF); 

    if (ch != '\n' && number_of_lines != 0) 
     number_of_lines++; 

    fclose(spData); 
    printf("There are %d lines in file grades.csv . \n", number_of_lines); 
    int amount = number_of_lines; 
    struct gradesRecord A[amount]; 
    printUnsortedStringFromFile(amount, A); 
    printSortedStringFromFile(amount, A); 
    //binSearchNUM(int amount, int A[amount], int target,); 
    return 0; 
} 

/* 
* Function Name: printUnsortedStringFromFile 
* 
* Input Parameters: takes array A 
* 
* Description: This fuction prints the original list that was unsorted in grades.csv 
* 
* Return Value: void 
*/ 
void printUnsortedStringFromFile(int amount, struct gradesRecord A[]) 
{ 
    FILE *spData; 
    spData = fopen("grades.csv", "r"); 
    if(spData == NULL) 
    { 
     fprintf(stderr, "Error opening the file grades.csv.\n"); 
     exit(1); 
    } 

    printf("+-------+------+------+------+-----+\n"); 
    printf("|Student|Exam 1|Exam 2|Exam 3|Grade|\n"); 
    printf("+-------+------+------+------+-----+\n"); 
    char sLine[81]; //local string to read one row 
    int j = 0; //storage index 
    while((fgets(sLine, 80, spData)) != NULL) 
    { 
    sscanf(sLine, "%d, %d, %d, %d, %c", 
     &(A[j].iStudentNUM), &(A[j].iExamGrouped[0]), &(A[j].iExamGrouped[1]), &(A[j].iExamGrouped[2]), 
     &(A[j].cStudentAVG)); 

    printf("|%7d| %5d| %5d| %5d| %c| \n", 
     A[j].iStudentNUM, A[j].iExamGrouped[0], A[j].iExamGrouped[1], A[j].iExamGrouped[2], 
     A[j].cStudentAVG); 
    j++; // next row 
    } 
    printf("+-------+------+------+------+-----+\n"); 

    if (fclose(spData) == EOF) 
    { 
     fprintf(stderr, "Error closing the file grades.csv. \n"); 
     exit(2); 
    } 
} 

/* 
* Function Name: printSortedStringFromFile 
* 
* Input Parameters: takes int amount, struct gradesRecord A 
* 
* Description: This function prints the sorted version of the file grades.csv omitting 
*    the exam values and giving each string a index number 
* 
* Return Value: void 
*/ 
void printSortedStringFromFile(int amount, struct gradesRecord A[]) 
{ 
    FILE *spData; 
    spData = fopen("grades.csv", "r"); 
    if(spData == NULL) 
    { 
     fprintf(stderr, "Error opening the file grades.csv.\n"); 
     exit(1); 
    } 

    char sLine[81]; 
    int iLine = 0, iRow; 
    struct gradesRecord grRow, grTmp; 

    while((fgets(sLine, 80, spData)) != NULL) 
    { 
    // extract one Row and store it into grRow 
    sscanf(sLine, "%d, %d, %d, %d, %c", 
     &(grRow.iStudentNUM), &(grRow.iExamGrouped[0]), &(grRow.iExamGrouped[1]), &(grRow.iExamGrouped[2]), 
     &(grRow.cStudentAVG)); 
    // keep the line index of that row 
     grRow.iIndex = iLine; 
    // target loop = insertion sort algorithm 
    for (iRow = 0; iRow < iLine; iRow++) 
     { 
     // detect if new student is before the store one 
     if (grRow.iStudentNUM < A[iRow].iStudentNUM) 
     { 
      // exchange both student records through grTmp 
      memcpy(&grTmp, &(A[iRow]), sizeof(struct gradesRecord)); 
      memcpy(&(A[iRow]), &grRow, sizeof(struct gradesRecord)); 
      memcpy(&grRow, &grTmp, sizeof(struct gradesRecord)); 
     } 
    } 
    // store the biggest student at the end 
     memcpy(&(A[iLine]), &grRow, sizeof(struct gradesRecord)); 
     iLine++; 
    } 
     int StudentNUM; 
     char StudentAVG; 
     int j = 0; 
     printf("+-----+-------+-----+\n"); 
     printf("|Index|Student|Grade|\n"); 
     printf("+-----+-------+-----+\n"); 

     int index; 
     while (j < amount - 1) 
    { 
     StudentNUM = A[j].iStudentNUM; 
     StudentAVG = A[j].cStudentAVG; 
     index = j+1; 
     printf("| %4d|%7d| %c| \n", index, StudentNUM, StudentAVG); 
     j++; 
    } 
     printf("+-----+-------+-----+\n"); 
    if (fclose(spData) == EOF) 
    { 
     fprintf(stderr, "Error closing the file grades.csv. \n"); 
     exit(2); 
    } 

} 

Answer 1

创建grades.csv这个输入格式：

Student,Exam 1,Exam 2,Exam 3,Grade 

例如：

1,18,17,14,18 
2,15,18,10,16 

和输出，不用其他任何错误，但是如果grades.csv不存在或者信息不正确，则会得到Segmentation fault (core dumped)

There are 3 lines in file grades.csv . 

+-------+------+------+------+-----+ 
|Student|Exam 1|Exam 2|Exam 3|Grade| 
+-------+------+------+------+-----+ 
|  1| 18| 17| 14| 1| 
|  2| 15| 18| 10| 1| 
+-------+------+------+------+-----+ 
+-----+-------+-----+ 
|Index|Student|Grade| 
+-----+-------+-----+ 
| 1|  1| 1| 
| 2|  2| 1| 
+-----+-------+-----+