C中的分段错误

Question

我正在尝试生成一个将值“val”附加到数组“ia”末尾的代码，但是我不断遇到分段错误。谁能帮我指出错误的来源可能来自哪里？

下面是我为任务 4 编写的测试代码。

intarr_result_t intarr_push( intarr_t* ia, int val )
{


    if (ia ==0)
    {
        return INTARR_BADARRAY;
    }

    //making space for newarr
    ia = realloc(ia, (ia->len + 1) * sizeof(intarr_t));

    //copying data from ia and val to newarr
    ia->data[ia->len - 1] = val;

    //ia = newarr;
    if (ia == 0)
    {
        return INTARR_BADALLOC;
    }
    else
    {
        return INTARR_OK;
    }


}

使用以下自定义头文件：

/* Structure type that encapsulates our safe int array. */
typedef struct {
  int* data;
  unsigned int len;
} intarr_t;

/* A type for returning status codes */
typedef enum {
  INTARR_OK,
  INTARR_BADARRAY,
  INTARR_BADINDEX,
  INTARR_BADALLOC,
  INTARR_NOTFOUND
} intarr_result_t;

/* TASK 4 */

// Append val to the end of ia (allocating space for it). If
// successful, return INTARR_OK, otherwise return
// INTARR_BADALLOC. If ia is null, return INTARR_BADARRAY.
intarr_result_t intarr_push( intarr_t* ia, int val );

// If the array is not empty, remove the value with the highest index
// from the array, and, if i is non-null, set *i to the removed value,
// then return INTARR_OK. If the array is empty, leave *i unmodified
// and return INTARR_BADINDEX. If ia is null, return INTARR_BADARRAY.
intarr_result_t intarr_pop( intarr_t* ia, int* i );

Answer 1

问题是你reallocia，而应该重新分配ia->data。 ia 本身的大小是恒定的，即sizeof(intarr_t)。正确的代码应该是：

ia->data = realloc(ia->data, (ia->len + 1) * sizeof(*ia->data));
/* ... */
if (ia->data == 0)
/* ... */
++ia->len;

Answer 2

你可以试试这个

/* Structure type that encapsulates our safe int array. */
typedef struct {
  int len;
  int data[];
} intarr_t;

intarr_result_t intarr_push(intarr_t** ia, int val )
{
    intarr_t *tmp = *ia;
    if (tmp ==0)
    {
        return INTARR_BADARRAY;
    }

    tmp = realloc(tmp, sizeof(intarr_t) + sizeof(int) * (tmp->len + 1));
    if (!tmp) return INTARR_BADALLOC;

    /* copying data from ia and val to newarr */
    tmp->data[tmp->len++] = val;
    *ia = tmp;

   return INTARR_OK;
}

int main(void)
{
    intarr_result_t res;
    intarr_t *arr = malloc(sizeof(intarr_t));

    if (!arr) return 1;
    res = intarr_push(&arr, 10);
    /* TODO: Something with result */
    res = intarr_push(&arr, 20);
    /* .... */
    return 0;
 }