malloc上的Seg故障

Question

我正在从一个文件中读取整数,当我尝试增长我的数组时,我在第二次调用时遇到了分段错误growMyArray(struct myArray),特别是在int *grownArray = malloc(arrayToGrow.maxCount * sizeof(int));:

struct myArray growMyArray(struct myArray arrayToGrow) {

    arrayToGrow.maxCount *= 2;

    int *grownArray = malloc(arrayToGrow.maxCount * sizeof(int));

    int i;
    for (i = 0; i < arrayToGrow.count; i++)
        grownArray[i] = arrayToGrow.numbers[i];

    free(arrayToGrow.numbers);

    arrayToGrow.numbers = grownArray;

    return arrayToGrow;
}

我的结构:

typedef struct myArray {
    int count;
    int maxCount;
    int *numbers;
} myArray;

从输入重定向读取:

struct myArray getRandomNumbers() {

    struct myArray randomNumbers;
    randomNumbers.count = 0;
    randomNumbers.maxCount = DEFAULT_SIZE;
    randomNumbers.numbers = malloc(randomNumbers.maxCount * sizeof(int));

    while (scanf("%d", &randomNumbers.numbers[randomNumbers.count]) == 1) {

        randomNumbers.count++;

        if (randomNumbers.count > randomNumbers.maxCount)
            randomNumbers = growMyArray(randomNumbers);
    }

    return randomNumbers;
}

我发现这特别奇怪,因为增长阵列总是第一次起作用但第二次不起作用.我DEFAULT_SIZE在一组大小为200000的测试数据上使用了多个值,范围从2到20000.

是否有明显的原因导致我在第二次调用时遇到分段错误growMyArray,特别是在int *grownArray = malloc(arrayToGrow.maxCount * sizeof(int));？

Answer 1

你写过数组的末尾.

while (scanf("%d", &randomNumbers.numbers[randomNumbers.count]) == 1) {

    randomNumbers.count++;

    if (randomNumbers.count > randomNumbers.maxCount)
        randomNumbers = growMyArray(randomNumbers);
}

因为您>在测试中使用,所以if只触发一次randomNumbers.count = randomNumbers.maxCount + 1,即scanf写入randomNumbers.numbers[randomNumbers.maxCount]超过数组末尾的写入.

因此,改变>以>=在if声明中出现.