Algorithm for the insert an element in the doubly list

Function INSERT (TEMPHEAD, KEY)

[This Function inserts an element after the node which the info filed equals to the KEY and the returns the address of the first node]

1. [Allocate the memory for the new node]

          NEW          NODE

          INFO (NEW) = X

2. [Insertion as the first node]

          RPTR (NEW) = TEMPHEAD

          LPTR (NEW) = NULL

          RPTR (TEMPHEAD) = NEW

          TEMPHEAD = NEW

          Return (TEMPHEAD)

3. [Save address of the first node]

          SAVE = TEMPHEAD

4. [Find the element after which we want to insert the element]

          Repeat thru step while RPTR (SAVE)! = NULL

5. [Check for the desire position]

          If INFO (RPTR (SAVE)) = KEY

                   Then

                             RPTR (NEW) = RPTR (SAVE)

                             LPTR (NEW) = SAVE

                             LPTR (RPTR (SAVE)) = NEW

                             RPTR (SAVE) = NEW

6. [Finished]

          Return (TEMPHEAD)