C# Queue Array

#include <stdio.h>

#define MAX 50
int queue_array[MAX]
int rear = - 1;
int front = - 1;
main()
{
    int choice;
    while (1)
    {
                printf("1.Insert element to queue \n");

        printf("2.Delete element from queue \n");

        printf("3.Display all elements of queue \n");

        printf("4.Quit \n");

        printf("Enter your choice : ");

        scanf("%d", &choice);

        switch (choice)

        {
            case 1:
            insert();
            break;
            case 2:
            delete();
            break;
            case 3:
            display();
            break;
            case 4:
            exit(1);
            default:
            printf("Wrong choice \n");
        }
    }
}
insert()
{
    int add_item;
    if (rear == MAX - 1)
    printf("Queue Overflow \n")
    else
    {
        if(front == - 1)
        front = 0;
        printf("Inset the element in queue : ");
        scanf("%d" , &add_item);
        rear = rear + 1;
        queue_array[rear] = add_item;
    }
}


delete()
{
    if(front == - 1 || front > rear)
    {
        printf("Queue Underflow \n");
        return ;
    }
    else
    {
        printf ("Element deleted from queue is : %
        front = front + 1;
    }
}
display()
{
    int i;
    if(front == - 1)
        printf("Queue is empty \n");
    else
    {
        printf("Queue is : \n");
        for (i - front; i <= rear. i++)
            printf("%d", queue_array[i]);
        printf("\n");
    }
}