顺序表-00007-扩容

typedef int seqType;	// 定义顺序表数据类型

// 定义顺序表的结构体
typedef struct t_sList
{
	seqType* pbase;		// 表基址
	int capacity;		// 表容量
	int size;			// 表长度
}mySList;

/**
* @brief 功能：扩容 \n
* @param[in] plist：表结构指针
* @param[in] inc：在表当前容量capacity上扩容inc，令total=capacity+inc,
* @param[in] inc：若total<capacity*DOUBLE,则令total=capacity*DOUBLE
* @retval OK(1)：扩容成功
* @retval ERROR(0)：表结构不存在，不可操作
* @retval OVERFLOW(-2)：扩容失败：申请堆空间失败导致
*/
status sList_expand(mySList* plist, int inc)
{
	if (plist == NULL || plist->pbase == NULL)
	{
		return ERROR;
	}
	int c = plist->capacity * DOUBLE;
	int total = (plist->capacity + inc < c) ? c : (plist->capacity + inc);
	seqType* pNew = NULL;

#if 1	// 用realloc，更方便
	pNew = (seqType*)realloc(plist->pbase, sizeof(seqType) * total);
	if (pNew == NULL)
	{
		return OVERFLOW;
	}
#endif 

#if 0	// 用malloc与memmove，自己实现
	pNew = (seqType*)malloc(sizeof(seqType) * total);
	if (pNew == NULL)
	{
		return OVERFLOW;
	}

	/*
		for (int i = 0; i < plist->capacity; i++)
		{
			pNew[i] = plist->pbase[i];
		}// 用malloc会发出缓冲区可能溢出的警告
	*/
	memmove(pNew, plist->pbase, sizeof(seqType) * (plist->capacity));
	free(plist->pbase);
#endif // 0

	plist->pbase = pNew;
	plist->capacity = total;
	return OK;
}//性能时高时低，性能低时是因为表满，需要扩容，将数据拷贝，导致的性能降低