87uu

#include <stdio.h> 
#include <stdlib.h> 

struct node {
	int data;
	struct node *next;
};
typedef struct node Node;

void createq();
void showfront();
void addq(int);
void delq();
void showqueue();
Node *front, *rear;

void createq() {
	front = rear = (Node*)malloc(sizeof(Node));
	front->next = rear->next = NULL;
}

void showfront() {
	if (front->next == NULL)
		printf("\n佇列為空！");
	else
		printf("\n頂端值：%d", front->next->data);
}

void addq(int data) {
	Node *newnode;
	newnode = (Node*)malloc(sizeof(Node));
	if (front->next == NULL)
		front->next = newnode;
	newnode->data = data;
	newnode->next = NULL;
	rear->next = newnode;
	rear = newnode;
}

void delq() {
	Node* tmpnode;

	if (front->next == NULL) {
		printf("\n佇列已空！");
		return;
	}

	tmpnode = front->next;
	front->next = tmpnode->next;
	free(tmpnode);
}

void showqueue() {
	Node* tmpnode;
	tmpnode = front->next;
	printf("\n佇列內容：");
	while (tmpnode != NULL) {
		printf("%d ", tmpnode->data);
		tmpnode = tmpnode->next;
	}
}

int main(void) {
	int input, select;

	createq();

	while (1) {
		printf("\n\n請輸入選項(-1結束)：");
		printf("\n(1)插入值至佇列");
		printf("\n(2)顯示佇列前端");
		printf("\n(3)刪除前端值");
		printf("\n(4)顯示所有內容");
		printf("\n\$c>");
		scanf("%d", &select);

		if (select == -1)
			break;

		switch (select) {
		case 1:
			printf("\n輸入值：");
			scanf("%d", &input);
			addq(input);
			break;
		case 2:
			showfront();
			break;
		case 3:
			delq();
			break;
		case 4:
			showqueue();
			break;
		default:
			printf("\n選項錯誤！");
		}
	}

	printf("\n");

	return 0;
}