Data Structures Queue C Program

Data Structures Lab Manual / Data Structures Queue C Program

Program Name: Write a C Program for Queue in Data Structures

Theory

A Queue is a linear structure (collection of items) which follows a First In First Out 
(FIFO) order in which the operations are performed.

Program Code

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

#define MAX 50 
void insert();
void delete();
void display();
int a[MAX];
int rear= - 1;
int front= - 1;

void main()
{
int choice;
while (1)
{
printf("Enter your choice : \n");
printf("Queue 1.Insert Element 2.Delete Element 3.Display all Elements 4.Quit  \n");
scanf("%d", &choice);

switch (choice)
{
case 1:insert();break;
case 2:delete();break;
case 3:display();break;
case 4:exit(1);
default:printf("Entered Wrong Choice \n");
} 
} 
}
 
void insert()
{
int add_item;
if (rear == MAX - 1)
printf("Queue Overflow \n");
else
{
if (front == - 1)
front = 0;
printf("Enter a Element to Insert in the Queue : ");
scanf("%d", &add_item);
rear = rear + 1;
a[rear] = add_item;
}
} 
 
void delete()
{
if (front == - 1 || front > rear)
{
printf("Queue Underflow \n");
}
else
{
printf("Element deleted from queue : %d\n", a[front]);
front = front + 1;
}
}

 
void display()
{
int i;
if (front == - 1)
printf("Queue is Empty \n");
else
{
printf("Queue is : \n");
for (i = front; i <= rear; i++)
printf("%d ", a[i]);
printf("\n");
}
}

Input:
Enter your choice : 
Queue 1.Insert Element 2.Delete Element 3.Display all Elements 4.Quit  
1
Enter a Element to Insert in the Queue : 9
Enter your choice : 
Queue 1.Insert Element 2.Delete Element 3.Display all Elements 4.Quit  
1
Enter a Element to Insert in the Queue : 6
Enter your choice : 
Queue 1.Insert Element 2.Delete Element 3.Display all Elements 4.Quit  
2
Element deleted from queue : 9
Enter your choice : 
Queue 1.Insert Element 2.Delete Element 3.Display all Elements 4.Quit  
3
Queue is : 
6 
Enter your choice : 
Queue 1.Insert Element 2.Delete Element 3.Display all Elements 4.Quit

Output:
Enter your choice : 
Queue 1.Insert Element 2.Delete Element 3.Display all Elements 4.Quit  
1
Enter a Element to Insert in the Queue : 9
Enter your choice : 
Queue 1.Insert Element 2.Delete Element 3.Display all Elements 4.Quit  
1
Enter a Element to Insert in the Queue : 6
Enter your choice : 
Queue 1.Insert Element 2.Delete Element 3.Display all Elements 4.Quit  
2
Element deleted from queue : 9
Enter your choice : 
Queue 1.Insert Element 2.Delete Element 3.Display all Elements 4.Quit  
3
Queue is : 
6 
Enter your choice : 
Queue 1.Insert Element 2.Delete Element 3.Display all Elements 4.Quit

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