#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#define max 100


int enqueue();
int dequeue();
int peek();

int main() {
    char name[max][80], data[80];
    int front = 0;
    int rear = 0;
    int value;
    int ch;
    printf("------------------------------\n");
    printf("\tMenu");
    printf("\n------------------------------");
    printf("\n [1] ENQUEUE");
    printf("\n [2] DEQUEUE");
    printf("\n [3] PEEK");
    printf("\n [4] DISPLAY");
    printf("\n------------------------------\n");
    while(1)
    {
        printf("Choice : ");
        scanf("%d", &ch);
        switch(ch) {
            case 1 : // insert
                printf("\nEnter the Name : ");
                scanf("%s",data);
                value = enqueue(name, &rear, data);
                if(value == -1 )
                    printf("\n QUEUE is Full \n");
                else
                    printf("\n'%s' is inserted in QUEUE.\n\n",data);
                break;
            case 2 : // delete
                value = dequeue(name, &front, &rear, data);
                if( value == -1 )
                    printf("\n QUEUE is Empty \n");
                else
                    printf("\n Deleted Name from QUEUE is : %s\n", data);
                printf("\n");
                break;
            case 3:
                value = peek(name, &front, &rear, data);
                if(value != -1)
                {
                    printf("\n The front is: %s\n", data);
                }
                break;
            case 5 : exit(0);
            default: printf("Invalid Choice \n");
        }
    }
    return 0;
}


int enqueue(char name[max][80], int *rear, const char data[80]) {
    if(*rear   1 == max)
        return -1;
    strcpy(name[*rear], data);
    (*rear)  ;
    return 1;
}

int dequeue(char name[max][80], int *front, int *rear, char data[80])
{
      if(*front == *rear)
            return(-1);
      else
      {
            (*front)  ;
            strcpy(data, name[*front]);
            return(1);
      }
}

int peek(char name[max][80], int *front, int *rear, char data[80]) {
    if(*front == *rear) {
        printf(" QUEUE IS EMPTY\n");
        return -1;
    }
    strcpy(data, name[*front]);
    return 1;
}

Student here.

My dequeue is not working correctly. The dequeue function is not deleting the first element but the second element. For example, The user, first inputs the name "Jennie" and then the second is "Lisa", when the user selects the dequeue function, "Jennie" should be deleted, but my program deletes the second element which is "Lisa". How to fix this?

CodePudding user response：

You need to increment the front after you dequeue the value:

int dequeue(char name[max][80], int *front, int *rear, char data[80])
{
    if(*front == *rear)
        return -1;
    strcpy(data, name[(*front)  ]);
    return 1;
}