Algorithmic Solutions > LEDA > LEDA Guide > Simple, Basic, and Advanced Data Types > Basic Data Types > Linear Lists

## Linear Lists

The data type list can be used to store a number of objects of an arbitrary type T sequentially. Each element in the list knows its predecessor and successor. The elements of a List are of type list_item.

### Example

The following program shows how to use lists. It generates a list L of int and appends the numbers 1 to 100 to L. Then it iterates over all elements of L and outputs each element. The last two lines of the program show how the first element of the list and the predecessor and successor of elements can be accessed.
#include <LEDA/core/list.h>

int main()
{
leda::list<int> L;

int i;
for (i=1; i<=100; i++) L.append(i);

forall(i,L) std::cout << i << " ";
std::cout << std::endl;

std::cout << L.inf(L.pred(L.succ(L.first()))) << std::endl;

return 0;
}

### Strengths

• space is proportional to current number of objects in the list
• objects are ordered sequentially
• inserting and deleting an element at a specified position is efficient (front and end of list, before and after an element)

• searching for an element is slow (proportional to the size of the list) (alternative: Sets)
• access to the i-th element of the list is slow (alternative: One Dimensional Array)

### Tips

• Use list if you frequently have to iterate over your objects or the number of objects to store varies a lot or if you need to insert/delete elements fast at an arbitrary position.
• If you do not need direct access to the predecessor of an element and memory is a major issue, consider using a Singly Linked List.
• If you need to search frequently, consider using a Set.
• If you need to access your objects by position frequently, consider using a One Dimensional Array.

Sets

Lists of Node

Manual Entries:

Manual Page Linear Lists

LEDA Item Concept