c语言 - 为什么我会收到"corrupted double-linked list"错误？

Question

程序

我正在用C写一个程序，它可以读取多项式系数的文档，并可以评估多项式的根。

在我的一个函数中，我试图读取文本文件，并创建一个"多项式"列表。多项式的定义如下:

typedef struct
{
    unsigned int nterms;       /* number of terms */
    double complex *polyCoef;  /* coefficients    */
} polynomial;

文本文件采用以下格式，其中每行代表一个多项式，每个数字代表一个系数:

1     0     0     0     2    -1
16    70  -169  -580    75
1     0     4     0    -5
0    -9     3     5    -3
5    -4     3    -2     0
1.0   -3.4    5.4531   -4.2077    1.5092   -0.2030

---

<标题>

我在我的实现尝试中得到一些奇怪的行为。使用下面的代码，我得到

*在'。/hw6': corrupt double-link list: 0x0000000000a1c240 *

    PolyFile = fopen(argv[2], "r"); 
    if(NULL == PolyFile){   /* If the file fails to open */
        fprintf(stderr, "Error: Input file '%s' not foundn", argv[2]); 
        return(-1); 
    }
    /****** Read in the polynomials *************/
    polynomials = malloc(sizeof(polynomial*) * size); /* Initialize */
    if(polynomials == NULL){
        fprintf(stderr, "%s %i: Could not allocate memoryn", __FILE__, __LINE__);
        exit(-99); 
    }
    /* Read all of the data from the file */
    while(fgets(String, MAX_STR_LEN, PolyFile)) {
        strLen = strlen(String); /* Determine size of line */
   /* Ensure that the line is not too long */
        if(strLen <= MAX_STR_LEN){
            /* Create the polynomial */
            p = (polynomial*)malloc(sizeof(polynomial)); 
            token = strtok(String, " ");
            while(token){
                coefficients[coeffCount] = token; 
                token = strtok(NULL, " ");
                coeffCount++;   
            } 
            createPoly(p, coeffCount); 
            /* Set p->polyCoef to the reverse of coefficients */            
            for(int lcv = 0; lcv <= coeffCount - 1; lcv++){
                p->polyCoef[lcv] = atof(coefficients[coeffCount - lcv - 1]) + 0.00*I; 
            }
            coeffCount = 0; 
            polynomials[size] = p;
            printf("P->NTERMS: %in", p->nterms); 
            size++; 
        } else {
            fprintf(stderr, "%s %i: Line too long. Polynomial ignoredn",
                        __FILE__, __LINE__); 
        }
    }
    fclose(PolyFile); 
    /**************************/
    for(int j = 0; j <= size - 1; j++){
        printf("J: %in", j); 
        printf("IN FOR LOOP: %in", (polynomials[j])->nterms); 
        // printPoly(polynomials[j]); 
        printf("n"); 
    }

…

/*---------------------------------------------------------------------------
  Creates a polynomial data structure with nterms.  This allocates storage
  for the actual polynomial.
  Where: polynomial *p       - Pointer to polynomial data structure to create
         unsigned int nterms - The number of elements to create
  Returns: nothing
  Errors:  prints an error and exits
---------------------------------------------------------------------------*/
void createPoly(polynomial *p, unsigned int nterms){
  int lcv; /* loop control variable */
  /* Create a polynomial struct */
  p->nterms = nterms; 
  p->polyCoef = (double complex*)malloc(sizeof(double complex)*nterms); 
  /* Error out if problem with malloc */
  if(p->polyCoef == NULL){
    fprintf(stderr, "%s %i:Error allocating memoryn", __FILE__, __LINE__); 
    exit(1); 
  }
  /* Set the coefficients to 0 */
  for(lcv = 0; lcv < nterms; lcv++){
    (p->polyCoef)[lcv] = 0.00 + 0.00*I; 
  }
}

如果我删除fclose(PolyFile);，代码继续，但是调试打印显示polynomials[0]->nterms等于一个随机的、变化的、非常大的数字。我不知道为什么会这样。

Answer 1

出现问题的原因是polynomials初始化时，size等于0:

polynomials = malloc(sizeof(polynomial*) * size);

通过使用文件中的行数分配适当的大小来解决这个问题。