• What is a list ?

    - It is a collection of similar components (e.g., names, telephone numbers, addresses, etc.)

    - The number of elements in the list is the length of the list

  • How can we implement a list ?

    - One way is using arrays (size >= length)

  • Common operations applied on lists

    - Create a list

    - Add an item to a list

    - Delete an item from a list

    - Search a list for a particular value

    - Sort a list (alphabetically or numerically)

  • Inserting an element (unsorted list)

  • Sequential search (unsorted list)

  • Sorting (Bubblesort)

    - Idea: Scan the list from left to right, swapping entries whenever a pair of adjacent elements is found to be out of order

    - Make n passes over the list (n: number of elements) 

    void Bubblesort(int list[], int length)
{
 int pass, i;
 int temp;

 for (pass = 1; pass < length; pass++)
   for(i = 0; i < length - 1; i++)
     if(list[i] > list[i+1]) 
     {
       temp = list[i];
       list[i] = list[i+1];
       list[i+1] = temp;
     }
}
  • Sequential search (sorted list)

    - An item is missing if we pass its correct place in the list !!

  • Inserting an element (sorted list)

  • Binary search: an improved searching approach for sorted lists 

    void BinarySearch(int list[], int item, int length, int& index)
{
 int first = 0;
 int last = length - 1;
 int middle, found;

 found=0;
 while( (last >= first) && (!found) )
 {
   middle = (first + last)/2; // integer division !!
   if(item < list[middle]) // reject lower part of the list
     last = middle - 1;
   else if(item > list[middle]) // reject upper part of the list
     first = middle + 1;
   else
     found = 1;

   if(found)
     index = middle;
   else
     index = length;
  }
}