Array implementation of lists

Static lists can be implemented using arrays as discussed in the previous section. 

Data Structure

struct List{
    int list[LISTMAXSIZE];
    int lastpos;
};

Initialization

lastpos = -1;

Insert Operation

1. Get list structure, position to insert and value to insert
2. If lastpos== MAXSIZE-1 or position > lastpos+1
              Return “INSERT INVALID”
   Else if position <= lastpos
           //shift element to right
           List[position] = item
           Lastpos++;
   Else
        List[++lastpos] = item

Delete Operation

1. Get list structure, position to delete
2. If lastpos== -1 or position > lastpos
              Return “INSERT INVALID”
   Else if position < lastpos
           Item = List[position]
           Lastpos--;
   Else
        Item = List[lastpos--]

Search Operation

1. Get list structure, key to search
2. Start from the first index of list
3. Compare the key with each and every element until lastpos is not reached.
4. If found, return the element.
5. If exceed the lastpos, then return invalid 

Write a C++ program to implement a list using a array.

#include<iostream>
#define SIZE 10
using namespace std;
class ArrayList{
   int cur_pos;
   int *arr;
   public:
   ArrayList(){
       cur_pos=-1;
       arr = new int[SIZE];
   }
   void insert_at_pos(int pos,int item){
       int temp;
       if(cur_pos==-1){
           cur_pos=0;
       }
       if((cur_pos==SIZE-1) || (pos>=cur_pos+1)){
           cout<<"invalid insert"<<endl;
           exit(0);
       }
       else{
           if(pos==cur_pos){
               arr[cur_pos++] = item;
           }
           else{
               temp = cur_pos;
               while(temp!=pos){
                   arr[temp] = arr[temp-1];
                   temp--;
               }
               arr[temp] = item;
               cur_pos++;
           }
       }
   }
   void delete_from_pos(int pos){
       int temp;
       if((cur_pos==-1)|| (pos>=cur_pos+1)){
           cout<<"invalid delete"<<endl;
           exit(0);
       }
       else{
           if(pos==cur_pos-1){
               cout<<"Element deleted is: "<<arr[pos]<<endl;
               cur_pos--;
           }
           else{
               temp=pos;
               cout<<"Element deleted is: "<<arr[pos]<<endl;
               while(temp!=cur_pos-1){
                   arr[temp] = arr[temp+1];
                   temp++;
               }
               cur_pos--;
           }
       }
   }
   void display(){
       int i;
       for(i=0;i<=cur_pos-1;i++){
           cout<<arr[i]<<" ";
       }
       cout<<endl;
   }
};
int main(){
   ArrayList l;
   l.insert_at_pos(0,10);
   l.insert_at_pos(1,20);
   l.insert_at_pos(2,30);
   l.insert_at_pos(3,40);
   l.insert_at_pos(2,100);
   l.delete_from_pos(2);
   l.display();
   return 0;
}