Array based QUEUE

What is it?

• Array 기반의 Queue
• 기본적으로 Enqueue (Insert), Dequeue (Delete) 연산이 가능한 FIFO (First-In, First-Out) 자료구조이다.
• 너무 간단한 코드라 자세한 설명은 생략한다.
• FIFO란? 먼저 들어온 자료가 먼저 나가는 것으로, 줄을 서다가 입장하는 것을 연상하면 된다.

CODE

/**************************************************
 * Array 기반의 Queue *****************************
 * ************************************ q.c ********
 * *************************************************/


#include <stdio.h>

#define MAX_BUFF 10



/* Data for Queue */
typedef struct qData
{
    int qkey;           // 키
    char qvalue;      // 값
} qData;


struct qData queue[MAX_BUFF];


/* Information for Queue */



int qTail;           /* 삽입되는 부분에 대한 정보 */
int qNum;         /* 입력받은 총 데이터 수 */
int countDe;     /* 현재 데이터의 개수를 위한 디큐 횟수 */


/*
 * Dequeue시 Head의 데이터를 삭제하는
 * 동시에 모든 데이터를 한칸씩 앞으로
 * 옮긺으로써 Head를 따로 선언하지 않음.
 */



/* Queue Initiation */

void qInit()
{
    qTail = 1;
    qNum = 0;
    countDe = 0;
    for(int i=0; i<MAX_BUFF; i++)
    {
        queue[i].qkey = '\0';
        queue[i].qvalue = '\0';
    }
}



/* Queue Print for Enqueue */

void qPrintEn()
{
    int i;       /* variable for 'for clause' */
    
    printf("\n Current Queue's status is :\n\n");
    printf("   KEY      VALUE\n");
    
    for( i = qTail-1  ; /*qTail-1*/
         i >= 0;  /*qHead-1*/
         i--)
    {
        printf("    %d        %s\n", queue[i].qkey, &queue[i].qvalue);
    }
    printf("\n");
    printf("The number of data which you into : %d\n", qNum);
    printf("The number of data which current exist : %d\n\n", qNum-countDe);      
}



/* Queue Print for Dequeue */

void qPrintDe()
{
    int i;        /* variable for 'for clause' */
    
    printf("\n Current Queue's status is :\n\n");
    printf("   KEY      VALUE\n");
    
    for( i = qTail-3 ; /* qTail-2 */
         i>=0;  /* qHead */
         i--)
    {
        printf("    %d        %s\n", queue[i].qkey, &queue[i].qvalue);
    }
    printf("\n");
    printf("The number of data which you into : %d\n", qNum);
    printf("The number of data which current exist : %d\n\n", qNum-countDe);      
}



/* Queue Insert the data 'val' */

void enQ(char val)
{
    if ( qTail >= 11 )
    {
        /* If the Queue is full */
        printf("\nerror::queue overflow.\n");
    }
    else
    {
        qNum++;
        queue[qTail-1].qkey = qNum;
        queue[qTail-1].qvalue = val;
        qPrintEn();
        qTail++;
    }
}



/* Queue Delete the data from head */

void deQ()
{
    if( qTail == 1 )
    {
        /* If the Queue is empty */
        printf("\nerror::queue is already empty.\n");
    }
    else
    {
        countDe++;
        printf("Deleted data : %s\n", &queue[0].qvalue);
        queue[0].qkey = '\0';
        queue[0].qvalue = '\0';
        for(int i=1; i<qTail; i++)
            {
                queue[i-1].qkey = queue[i].qkey;
                queue[i-1].qvalue = queue[i].qvalue;
            }

        qPrintDe();
        qTail--;

    }
}


/* MAIN FUNCTION */
int main()
{
    qInit();
    printf("\n\nIt's an array based Queue.\n\n");
    int  menu;
    char  push;

    while(menu!=3)
    {
        printf("\nYou make a choice to menu.\n\n");
        printf("Press '0' If you wanna Initiation.\n");
        printf("Press '1' If you wanna Enqueue.\n");
        printf("Press '2' Ifyou wanna Dequeue.\n");
        printf("Press '3' If you wanna exit.\n\n");
        printf(" PRESS : ");
        scanf("%d", &menu);

        switch(menu)
        {
            case 0:
                printf("You pressed '0' to Initiation.\n");
                printf("So, the stack is cleared.\n");
                qInit();
                qPrintDe();
                break;
            case 1:
                printf("You pressed '1' to Enqueue.\n");
                printf("Press the character which you want to Enqueue. : ");
                scanf( "%s", &push );
                enQ(push);
                break;
            case 2:
                printf("You pressed '2' to Dequeue.\n");
                deQ();
                break;
            case 3:
                printf("Exit......\n\n");
                break;
            default:
                printf("It's wrong number. press again.\n\n");
                break;
        } // switch

    } // while
    
    
  
    return 0;
}