realloc():两次计算后的下一个大小无效

问题描述 投票:0回答:1

我创建了存储数字数组的结构。该数组是动态分配的。尝试在函数中重新分配一些空间时会发生此问题。错误是

realloc(): invalid next size
Aborted (core dumped)

结构如下

typedef struct big_number {
    unsigned int *digits;
    int num_of_digits;
}BigNumber;

该函数看起来像这样(使用BigNumber乘以数字):

void scale(BigNumber a, int c, BigNumber* scaled)
{
    scaled->num_of_digits = a.num_of_digits;
    scaled->digits = NULL;
    scaled->digits = malloc(scaled->num_of_digits * sizeof (unsigned int));

    if (scaled->digits == NULL) {
        error();
    }

    int carry = 0;
    for (int i = scaled->num_of_digits; i >= 0; i--) {
        int tmp = a.digits[i] * c + carry;
        scaled->digits[i] = tmp % 10;
        carry = tmp / 10;
    }

    if (carry != 0) {
        //While trying realloc in this line problem occurs
        scaled->num_of_digits += 1;
        scaled->digits = realloc(scaled->digits, scaled->num_of_digits * sizeof (unsigned int));
        scaled->digits[0] = carry;
    }
}

main中的调用如下所示:

    printf("Results:\n");

    scale(num_b, 5, &pomocna);
    print_big_number(pomocna);
    free(pomocna.digits);
c function malloc structure realloc
1个回答
2
投票

阵列从0n-1。您正在写信给不存在的array[n]

scaled->digits = malloc(scaled->num_of_digits * sizeof (unsigned int));
for (int i = scaled->num_of_digits; i >= 0; i--) { // AAA
        int tmp = a.digits[i] * c + carry;
        scaled->digits[i] = tmp % 10;             // BBB

在AAA线中,你将i设置为数组的大小(到n

在BBB线你尝试改变scaled->digits[i]array[n]

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