code added

addnodeatmiddleSLL.c

@@ -0,0 +1,132 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+struct node 
+{
+    int num;                    //Data of the node
+    struct node *nextptr;       //Address of the node
+}*stnode;
+
+void createNodeList(int n);     				//function to create the list
+void insertNodeAtMiddle(int num, int pos);	    //function to insert node at the middle
+void displayList();             				//function to display the list
+
+int main()
+{
+    int n,num,pos;
+		printf("\n\n Linked List : Insert a new node at the middle of the Linked List :\n");
+		printf("-----------------------------------------------------------------------\n");
+
+    printf(" Input the number of nodes (3 or more) : ");
+    scanf("%d", &n);
+    createNodeList(n);
+    printf("\n Data entered in the list are : \n");		
+    displayList();
+    printf("\n Input data to insert in the middle of the list : ");
+    scanf("%d", &num);
+    printf(" Input the position to insert new node : " );
+    scanf("%d", &pos);
+        if(pos<=1 || pos>=n)
+    {
+     printf("\n Insertion can not be possible in that position.\n ");
+    }
+        if(pos>1 && pos<n)      
+      {
+              insertNodeAtMiddle(num, pos);
+       printf("\n Insertion completed successfully.\n ");
+      }
+    printf("\n The new list are : \n");		
+    displayList();
+    return 0;
+}
+void createNodeList(int n)
+{
+    struct node *fnNode, *tmp;
+    int num, i;
+    stnode = (struct node *)malloc(sizeof(struct node));
+    if(stnode == NULL) //check whether the stnode is NULL and if so no memory allocation
+    {
+        printf(" Memory can not be allocated.");
+    }
+    else
+    {
+// reads data for the node through keyboard
+        printf(" Input data for node 1 : ");
+        scanf("%d", &num);
+        stnode-> num = num;      
+        stnode-> nextptr = NULL; //Links the address field to NULL
+        tmp = stnode;
+//Creates n nodes and adds to linked list
+        for(i=2; i<=n; i++)
+        {
+            fnNode = (struct node *)malloc(sizeof(struct node));
+            if(fnNode == NULL) //check whether the fnnode is NULL and if so no memory allocation
+            {
+                printf(" Memory can not be allocated.");
+                break;
+            }
+            else
+            {
+                printf(" Input data for node %d : ", i);
+                scanf(" %d", &num);
+
+                fnNode->num = num;      // links the num field of fnNode with num
+                fnNode->nextptr = NULL; // links the address field of fnNode with NULL
+
+                tmp->nextptr = fnNode; // links previous node i.e. tmp to the fnNode
+                tmp = tmp->nextptr;
+            }
+        }
+    }
+} 
+
+void insertNodeAtMiddle(int num, int pos)
+{
+    int i;
+    struct node *fnNode, *tmp;
+    fnNode = (struct node*)malloc(sizeof(struct node));
+    if(fnNode == NULL)
+    {
+        printf(" Memory can not be allocated.");
+    }
+    else
+    {
+        fnNode->num = num; //Links the data part
+        fnNode->nextptr = NULL;
+        tmp = stnode;
+        for(i=2; i<=pos-1; i++)
+        {
+            tmp = tmp->nextptr;
+
+            if(tmp == NULL)
+                break;
+        }
+        if(tmp != NULL)
+        {
+            fnNode->nextptr = tmp->nextptr;  //Links the address part of new node
+            tmp->nextptr = fnNode;   
+        }
+        else
+        {
+            printf(" Insert is not possible to the given position.\n");
+        }
+    }
+}
+
+void displayList()
+{
+    struct node *tmp;
+    if(stnode == NULL)
+    {
+        printf(" No data found in the empty list.");
+    }
+    else
+    {
+        tmp = stnode;
+        while(tmp != NULL)
+        {
+            printf(" Data = %d\n", tmp->num);   // prints the data of current node
+            tmp = tmp->nextptr;                 // advances the position of current node
+        }
+    }
+}