C언어 이분탐색 질문

int idxsearch(int ar[], int first, int last, int target) 
{
    int mid = (first + last) / 2;
 
    if (first > last)
    {
        printf("-1\n");
        printf("\n");
        return -1;
    }
    else
    {
	if (ar[mid] == target)
        {
            printf("mid : %d\n", mid);
            printf("\n");
            return mid;
        }
	else
        {
            if (ar[mid] > target)
            {
	        last = mid - 1;
                printf("last1 %d\n", last);
		idxsearch(ar, first, last, target);
                printf("last2 %d\n", last);
	    }
	    else
            {
	        first = mid + 1;
                printf("first1 %d\n", first);
		idxsearch(ar, first, last, target);
                printf("first2 %d\n", first);
	    }
        }
    }
    printf("return 0\n");
    printf("\n");
    return 0;
}
 
 
//이분 탐색(Binary Search) - C언어
//https://blog.naver.com/jsky10503/221248921302
int idxsearch2 (int ar[], int first, int last, int target) 
{
    int mid;
    while(1)
    {
        mid = (first + last) / 2;
 
        if (ar[mid] < target)
        {
            first = mid + 1;
            printf("first : %d\n", first);
        }
        else if(ar[mid] > target)
        {
            last = mid - 1;
            printf("last : %d\n", last);
        }
        else
        {
            break;
        }
    }
    printf("target %d    ar %d\n", target, mid);
    return 0;
}
 
 
 
int idxsearch3 (int ar[], int left, int right, int target) 
{
    static int count = 0;
    int mid = (left + right) / 2;
 
    printf("현재 값 : %d\n", ar[mid]);
 
    count = count + 1;
    printf("검색 횟수 확인 : %d\n", count);
    if(count > 10)
    {
        printf("검색 횟수를 초과했습니다.\n");
        return 0;
    }
 
    //
    if (target == ar[mid])
    {
        printf("찾는값이 중간값과 같으면. 찾았다.\n");
        return target;
    }
 
    //
    else if (ar[mid] < target)
    {
        printf("찾는값이 중간값 보다 크다면. 중간값 부터 오른쪽으로 검색\n");
        left = mid;
        idxsearch3(ar, left, right, target);
    }
 
    //
    else
    {
        printf("찾는값이 중간값 보다 작으면. 중간값 부터 왼쪽으로 검색\n");
        right = mid;
        idxsearch3(ar, left, right, target);
    }
    printf("return 0\n");
    printf("\n");
    return 0;
}
 
 
int main()
{
//	scanf_s(" %d", &num);
        int num = 10;
	int *inorder = (int*)malloc(sizeof(int)*num);
	int *levelorder = (int*)malloc(sizeof(int)*num);
 
//	for (int i = 0; i < num; i++)
//		scanf_s(" %d", &inorder[i],sizeof(int));
inorder[0] = 10;
inorder[1] = 20;
inorder[2] = 30;
inorder[3] = 40;
inorder[4] = 50;
inorder[5] = 60;
inorder[6] = 70;
inorder[7] = 80;
inorder[8] = 90;
	printf("\n");
        printf("\n");
 
//	printf("idxsearch %d\n", idxsearch(inorder, 0, num-1, 80));
//	printf("idxsearch %d\n", idxsearch(inorder, 0, num-1, 20));
 
//	printf(" %d\n", idxsearch2(inorder, 0, num-1, 80));
//	printf(" %d\n", idxsearch2(inorder, 0, num-1, 20));
 
	printf(" %d\n", idxsearch3(inorder, 0, num-1, 40));
 
	//printsol();
	free(levelorder);
	free(inorder);
}