{"post":"

Let’s review queue and understand its implementation now. As we already discussed that queue are also abstract data type data structures following FIFO (First-In-First-Out) principle. A queue is similar to a checkout line at a bus stand. The first one in the line will also be the first one to move out after being issued a bus ticket.

Let’s look at the sample program to understand the Insertion, deletion and traverse the elements of the queue.

//the program shows the basic operations performed on a queue\n#include <iostream.h>\n#include <stdio.h>\n#include <conio.h>\n#include <stdlib.h>\n#include <ctype.h>\n// declares a queue structure
\nstruct node
\n{
\nchar data;\n\nnode * link;\n
\n};
\n//functions to add, delete and show queue
\nnode* add_Q(node *rear, char value);\t//add queue
\nnode* del_Q(node *front, char &value);\t//delete queue
\nvoid show_Q(node *front);
\n//main program
\nvoid main()
\n{
\nnode *front, *rear;\n\nchar value;\n\nint choice;\n\nchar option = ’Y’;\n\nfront = rear = NULL;\n\nclrscr();\n\ndo\n\n{\n\n\tcout &lt;&lt; ”\\n Main Menu”;\n\n\tcout &lt;&lt; ”\\n Adding in Queue”;\n\n\tcout &lt;&lt; ”\\n Delete from Queue”;\n\n\tcout &lt;&lt; ”\\n Traverse the queue”;\n\n\tcout &lt;&lt; ”\\n Exit Main Menu”;\n\n\tcout &lt;&lt; ”\\n Enter a choice from Main Menu”;\n\n\tcin &gt;&gt; choice;\n\n\tswitch (choice)\n\n\t{\n\n\t\tcase 1:\n\n\t\t\tdo\n\n\t\t\t{\n\n\t\t\t\tcout &lt;&lt; ”Enter the item to be added to the queue”;\n\n\t\t\t\tcin &gt;&gt; value;\n\n\t\t\t\trear = add_Q(rear, value);\n\n\t\t\t\tif (front == NULL)\n\n\t\t\t\t\tfront = rear;\n\n\t\t\t\tcout &lt;&lt; ”\\n Add more element &lt; Y / N &gt; ? ”;\n\n\t\t\t\tcin &gt;&gt; option;\n\t\t\t} while (toupper(option) == ’Y’);\n\n\t\t\tbreak;\n\n\t\tcase 2:\n\n\t\t\toption = ’Y’;\n\n\t\t\tdo\n\n\t\t\t{\n\n\t\t\t\tfront = del_Q(front, value);\n\n\t\t\t\tif (front == NULL)\n\n\t\t\t\t\trear = front;\n\n\t\t\t\tif (value != -1)\n\n\t\t\t\t\tcout &lt;&lt; ”\\n Item deleted from queue is”;\n\n\t\t\t\tcout &lt;&lt; ”\\n Delete more items from the queue&lt; Y / N &gt; ? ”;\n\n\t\t\t\tcin &gt;&gt; option;\n\t\t\t} while (toupper(opt) == ’Y’);\n\n\t\t\tbreak;\n\n\t\tcase 3:\n\n\t\t\tshow_Q(front);\n\n\t\t\tbreak;\n\n\t\tcase 4:\n\n\t\t\texit(0);\n\t}\n}\n\nwhile (choice != 4);\n
\n}
\n//to add elements to the queue
\nnode* add_Q(node *rear, char value)
\n{
\nnode * temp;\n\ntemp = new node;\n\ntemp-&gt;data = value;\n\ntemp-&gt;link = NULL;\n\nrear-&gt;link = temp;\n\nrear = temp;\n\nreturn (rear);\n
\n}
\n// to delete items from queue
\nnode* del_Q(node *front, char &value)
\n{
\nnode * temp;\n\nclrscr();\n\nif (front == NULL)\n\n{\n\n\tcout &lt;&lt; ”queue is empty”;\n\n\tval = -1;\n}\nelse\n\n{\n\n\ttemp = front;\n\n\tfront =-&gt;link;\n\n\tvalue = temp-&gt;data;\n\n\ttemp-&gt;link = NULL;\n\n\tdelete temp;\n}\n\nreturn (front);\n
\n}
\n// show elements of the queue
\nvoid show_Q(node *front)
\n{
\nnode * temp;\n\ntemp = front;\n\nclrscr();\n\ncout &lt;&lt; ”Elements of queue are”;\n\nwhile (temp != NULL)\n\n{\n\n\tcout &lt;&lt; ”\\n” &lt;&lt; temp-&gt;data;\n\n\ttemp = temp-&gt;link;\n}\n
\n}

\n","title":"Queue implementation using C++","authorDetails":{"name":"Sonal Moga","slug":"sonal-moga"},"description":"Let’s look at the sample program to understand the Insertion, deletion and traverse the elements of the queue in C++.","slug":"data-structure/queue-implementation-using-cpp/","articleId":"636a83447bb1ce5072622b7f","bookmarkStatus":{"isBookmarked":false,"bookmarkId":null}}