gtQkFM - Online C Compiler & Debugging Tool

#include <stdio.h>

#define SIZE 5
int queue[SIZE];
int head, tail;

void enqueue(int value);
int dequeue(void);

int main(void){
    head = tail = 0;
    int resp, data, i;

    while(1){
        printf("\n1: enqueue  2: dequeue  0: end → ");
        scanf("%d", &resp);

        if(!resp) break;

        switch(resp){
            case 1:
                printf("enqueue → ");
                scanf("%d", &data);
                enqueue(data);
                break;
            case 2:
                dequeue();
                break;
            default:
                printf("入力エラーです。\n");
                break;
        }

        printf("head=%d, tail=%d\n", head, tail);

        i = head;
        while(i != tail){
            printf("queue[%d] = %d\n", i, queue[i]);
            i = (i + 1) % SIZE;
        }
    }

    return 0;
}

void enqueue(int value){
    int next = (tail + 1) % SIZE;

    if(next == head){
        printf("キューが満杯です！\n");
        return;
    }

    queue[tail] = value;
    tail = next;
    printf("%d を追加しました。\n", value);
}

int dequeue(void){
    if(head == tail){
        printf("キューが空です！\n");
        return -1;
    }

    int value = queue[head];
    head = (head + 1) % SIZE;
    printf("%d を取り出しました。\n", value);
    return value;
}