Intro to Lists

Lists

List• A list is a consecutive group of mutable memory locations.

• Each element can be a different type

• Each individual value in an list is referred to as an element.

• The position number is more formally called a subscript or index.• Subscripts must be an integer• Can use an expression as an index.

• The first element in every kist has subscript 0 (zero) and is sometimes called the zeroth element.

• To refer to a particular location or element in the list, specify the name of the list and the index of the particular element.

• The size of an list is how many elements in the list, denoted by n.

• The highest subscript in an list is n - 1.

Checkpoint:•1. What is the size of an array?

•2. What is the range of indices of an array?

Refer to the following array:int age[] = {10, 11, 18, 13, 13, 16, 41, 12};

•3. What is in the 7th position in the array?

•4. What element is storing the value 12?

List Initializer

•To create and initialize a list is similar to a variable declaration only with multiple elements instead od a single one:

Code: listName = [ele1, ele2, …]

Ex. ▫names = [“Frankenstein”, Werewolf”,

“Boogeyman”]▫ages = [18, 18, 21, 21, 21, 22, 35, 38, 32, 36]▫Combo=[23, “Cake”, “Cupcakes”, 34]

Traversing an Array• In order to access each element of an array we

must hard code each statement which can take up lots of code.

• Also if we are trying to program in the general if we add an extra element we have to change all of our code

▫Question: How could we traverse or iterate through this list more efficiently?

VS

Reasons traversing an array with a for loop helps with programming in the general•Updating•Mathematical operations ( ie. Summing)•Printing •Searching•Testing

Common List Functions

Declaring Lists Lists are dynamic data structures

To declare a list when not initializing:○ Code: listName =[]

The interpreter reserves memory as it is needed. In order to add an item to a List use the append

function. Code: listName.append(value)

Note: Add element vs. update element

Other List Functions