Chris is interviewing candidates for a job. He will call each candidate in order, represented by a Python list:
calls = ['Ali', 'Bob', 'Cam', 'Doug', 'Ellie']
First, he’ll call 'Ali'
, then 'Bob'
, etc.
In Python, we call the order of an element in a list its index.
Python lists are zero-indexed. This means that the first element in a list has index 0
, rather than 1
.
Here are the index numbers for that list:
Element | Index |
---|---|
'Ali' |
0 |
'Bob' |
1 |
'Cam' |
2 |
'Doug' |
3 |
'Ellie' |
4 |
In this example, the element with index 2
is 'Cam'
.
We can select a single element from a list by using square brackets ([]
) and the index of the list item. For example, if we wanted to select the third element from the list, we’d use calls[2]
:
>>> print(calls[2]) 'Cam'
Note that when accessing elements of an array, you must use an int
as the index. If you use a float
, you will get an error. This can be especially tricky when using division. For example print(calls[4/2])
will result in an error, because 4/2
gets evaluated to the float
2.0
.
To solve this problem, you can force the result of your division to be an int
by using the int()
function. int()
takes a number and cuts off the decimal point. For example, int(5.9)
and int(5.0)
will both become 5
. Therefore, calls[int(4/2)]
will result in the same value as calls[2]
, whereas calls[4/2]
will result in an error.
Instructions
Use square brackets ([
and ]
) to select the element with index 4
from the list employees
. Save it to the variable index4
.
Use print
and len
to display how many items are in employees
.
Paste the following code into script.py:
print(employees[8])
What happens? Why?
Selecting an element that does not exist produces an IndexError
.
In the line of code that you pasted, change 8
to a different number so that you don’t get an IndexError
.