# length()

Return the length of a list expression.

## Synopsis

length(list-expression)


## Description

The length() function is used to find the number of elements in a list. Since lists are 0-indexed, the index of the last item in a list of length $$n$$ is $$n-1$$.

## Parameters

list-expression

an expression that evaluates to a list

## Returns

The length of the list expression.

## Examples

Find the length of a list. This returns 3.

length(list(1,1,1))


Find the value of the last element in a list X. This sets last_item to 5.

X = list(1,2,3,4,5)
last_item = X[length(X)-1]


## Errors

It is an error if the argument to length() is not a list-expression.