在表中查找数组为x的元素

线性表（a1,a2,a3……an）中的元素递增有序且按顺序存储于计算机中，设计一算法，在表中查找数组为x的元素，若找到则将其与后继元素位置交换，找不到则插入x并依然递增有序
思路：为了加快查找速度，这里采用折半查找法

#include<stdio.h>
#include<stdlib.h>
#define LIST_INIT_SIZE 100
#define LISTINCREMENT 20

typedef struct
{
	int *elem;
	int length;
	int listsize;
}SqList;

bool InitList_Sq(SqList &L);
void PrintElem_Sq(SqList L);
void SearchExchangeInsert(SqList &L, int x);
int main()
{
	int x;
	SqList L;
	InitList_Sq(L);
	L.elem[0] = 0;
	L.elem[1] = 2;
	L.elem[2] = 4;
	L.elem[3] = 6;
	L.elem[4] = 8;
	L.length = 5;
	printf("请输入要在顺序表中查找的元素x：");
	scanf("%d", &x);
	SearchExchangeInsert(L, x);
	PrintElem_Sq(L);
	return 0;
}
bool InitList_Sq(SqList &L)
{
	L.elem =(int*)malloc(LISTINCREMENT*sizeof(int));
	if(!L.elem)
		return false;
	L.length = 0;
	L.listsize = LIST_INIT_SIZE;
	return true;
}
void PrintElem_Sq(SqList L)
{
	if(L.length == 0)
		printf("顺序表为空");
	else
		for(int i = 0; i < L.length; i ++)
			printf("%d ", L.elem[i]);
}
void SearchExchangeInsert(SqList &L, int x)//二分查找 
{
	int low = 0,high = L.length-1, mid;
	int i;
	while(low <= high)
	{
		mid = low + (high - low) / 2;
		if(L.elem[mid] == x) 
			break;
		else if (L.elem[mid] < x)
			low = mid + 1;
		else 
			high = mid - 1;//?
	}
	if (L.elem[mid] == x && mid != L.length-1)
	{
		int t = L.elem[mid];
		L.elem[mid] = L.elem[mid + 1];
		L.elem[mid + 1] = t;
	}

	if (low > high)
	{
		L.length ++;
		for (i = L.length-1; i > high; i--)
			L.elem[i + 1] = L.elem[i];
		L.elem[i + 1] = x;
		
	}
}