1
Variables and I/O
Types
• Strings
– En closed in quotation marks
– “H ello, World!”
• Integers
– 4, 3, 5, 65
• Floats
– 4.5 , 0.7
• What about “56” ?
Variables and Assignment
• A name that refers to a value
• Python uses dynamic typing
my_num = 6
my_string = “Hello”
another_num = my_num
Variables and Assignment
• = often read as “gets the value”
• my_num and another_num refer to the
same object
my_num = 6
my_string = “Hello”
another_num = my_num
6
“Hello”
my_string
my_num
another_num
Variables and Assignment
• Numbers and strings are immutable
my_num = 6
my_string = “Hello”
another_num = my_num
my_num = 7
my_num = “CS”
“Hello”
my_string
my_num
another_num
7
6
Variable Names
• A combination of letters, digits, and _
• Must begin with a letter
• Case sensitive
• OKAY
–csiscool, my_variable variable2
• NOT OKAY
–cs is cool, 2ndv ariable, print
• Why not print?
