How to Insert ,Delete nodes in between the Linked List

Node definition (Structure) :

struct node{
 int num;
 node* next;
};

The num variable stores the data given by the user and the pointer (next) stores the address of the next element present in the linked list.

Insertion in between nodes (After a given node ) :

void insert_inBetween(){
 int cvalue,value;
 cout<<"Enter the value after which you want to insert the new node"<<endl;
 cin>>cvalue;
 cout<<"enter the value of new node: ";
 cin>>value;
 cout<<endl;
 node *n,*prev;
 n->num=value;
 if(prev=find(cvalue,0)){
  n->next = prev->next;
  prev->next=n;
  cout<<"node inserted succesfully";
 }
 else{
  cout<<"Node value not found";
 }
}

for performing the insertion after an element given by the user , we need to know the location of the node after which it is to be inserted, for this another function (find()) will be called which will return the address of the node after which we have to insert the new node.

the function ( find() ) accepts two arguments value and the relative position of node (-1,0,1).

-1 : return the previous node

0 : return the current node

1 : return the next node

node* find(int cvalue,int p){
 node* temp=first;
 node* prev;
 prev=temp;
 while(temp){
  
  if(temp->num==cvalue){
   if(p==-1)
    return prev;
   if(p==0)
    return temp;
   if(p==1)
    return temp->next;
  }
  prev=temp;
  temp=temp->next;
 }
 return NULL;
}

Now, after finding the location of node we just have to assign the current node's next value to the node after (prev) (the node where the value given by the user is stored ) .

and then link the new node (current) address to the prev->next to complete the joining in linked list.

Deletion in between nodes :

void delete_node(){
 int dValue;
 cout<<"Enter the value you want to delete; ";
 cin>>dValue;
 if(first->num==dValue){
  node* t1=first;
  first=first->next;
  delete(t1);
 }
 else{
  node* prev=find(dValue,-1);
  node* dNode=prev->next;
  if(prev!=NULL){
   prev->next=dNode->next;
   delete(dNode);
  }
  else
   cout<<"Value not found"<<endl;
 }
}

Here, also the find() function is called with parameter (-1) (ie: The function will return the node which comes before the node which is to be deleted )

if the node with the required value is found then first ,the previous node (returned by find()) will be linked with the next node of node(going to be deleted) and then the memory is de-allocated for dNode .

if any doubts or queries please comment