Add circular queue

Data Structures/Queue/CIRQUEUE.C

@@ -0,0 +1,110 @@
+#include<stdio.h>
+#include<conio.h>
+#define MAX 5
+
+int queue[MAX];
+int front = -1, rear = -1;
+void insert();
+int delete();
+int peek();
+void display();
+
+void main() {
+    int ch, val;
+    clrscr();
+    while (1) {
+        printf("MENU : ");
+        printf(" 1. Insert\t2. Delete\t3. Peek\t\t4. Display\t5. EXIT");
+        printf("\nEnter your option: ");
+        scanf("%d", & option);
+        switch (ch) {
+        case 1:
+            insert();
+            break;
+        case 2:
+            val = delete();
+            if (val != -1)
+                printf("\nThe number deleted is: %d", val);
+            printf("\n\n");
+            break;
+        case 3:
+            val = peek();
+            if (val != -1)
+                printf("\nThe value at front of the queue is: %d", val);
+            printf("\n\n");
+            break;
+        case 4:
+            display();
+            break;
+        case 5:
+            exit(0);
+        }
+    }
+}
+
+void insert() {
+    int num;
+    printf("\nEnter the number to be inserted in the queue: ");
+    scanf("%d", & num);
+    if (front == 0 && rear == MAXSIZE - 1)
+        printf("\nQueue Full!!");
+    else if ((rear+1) == front) {
+      printf("\nQueue Full!!");
+    } else if (front == -1 && rear == -1) {
+        front = rear = 0;
+        queue[rear] = num;
+    } else if (rear == MAX - 1 && front != 0) {
+        rear = 0;
+        queue[rear] = num;
+    } else {
+        rear++;
+        queue[rear] = num;
+    }
+    printf("\n");
+}
+
+int delete() {
+    int val;
+    if (front == -1 && rear == -1) {
+        printf("\nQueue Empty!!");
+        return -1;
+    }
+    val = queue[front];
+    if (front == rear)
+        front = rear = -1;
+    else {
+        if (front == MAX - 1)
+            front = 0;
+        else
+            front++;
+    }
+    return val;
+}
+
+int peek() {
+    if (front == -1 && rear == -1) {
+        printf("\nQueue Empty!!");
+        return -1;
+    } else {
+        return queue[front];
+    }
+}
+
+void display() {
+    int i;
+    printf("\n");
+    if (front == -1 && rear == -1)
+        printf("\nQUEUE IS EMPTY");
+    else {
+        if (front < rear) {
+            for (i = front; i <= rear; i++)
+                printf("\t%d", queue[i]);
+        } else {
+            for (i = front; i < MAX; i++)
+                printf("\t %d", queue[i]);
+            for (i = 0; i <= rear; i++)
+                printf("\t%d", queue[i]);
+        }
+    }
+    printf("\n\n");
+}