Exercises on names

This page has some exercises that relate most directly to the names section.

Here are some assignment statements. Are these valid names? Why - or why not? When you have an answer, try the names in a Notebook cell, and see what you get:

five = 5

Five = 5

five_Point_three = 5

five3 = 5

_five_ = 5

five_3 = 5

five.3 = 5

3five = 5

five-point-three = 5

Look at these blocks of lines below, and try and work out what each of these expressions will return. Are they valid expressions? Will they give an error?

Don’t enter the lines into the notebook until you have worked out your answer. When you do have an answer, try entering the expression as cells in the notebook:

a = 5
b = 3
a + b * 4

a = 5
a = a + 3
a

a = 5
b = a + 3
a = 3
b

first_variable = 5
second_variable = first_variable + 3
first_variable = 3
second_variable

a = 5
a * 3 * c

a = 5
a 5 + 4 * 3

This one is more tricky, and uses stuff you have not yet seen. Look at this and try and predict what you would see, after you run these two statements. Then try running them in a Notebook or in Python. What do you see? Why?

my_variable == 5
my_variable * 4

Hint: look carefully at the equals in the first statement. You may want to do a web-search to see what is going on.