1.3: Variables
- Page ID
- 117515
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- Assign variables and print variables.
- Explain rules for naming variables.
Assignment statement
Variables allow programs to refer to values using names rather than memory locations. Ex: age
refers to a person's age, and birth
refers to a person's date of birth.
A statement can set a variable to a value using the assignment operator (=). Note that this is different from the equal sign of mathematics. Ex: age = 6
or birth = "May 15"
. The left side of the assignment statement is a variable, and the right side is the value the variable is assigned.
city = "London"
print("The city where you live is", city)
Variable naming rules
A variable name can consist of letters, digits, and underscores and be of any length. The name cannot start with a digit. Ex: 101class
is invalid. Also, letter case matters. Ex: Total
is different from total
. Python's style guide recommends writing variable names in snake case, which is all lowercase with underscores in between each word, such as first_name
or total_price
.
A name should be short and descriptive, so words are preferred over single characters in programs for readability. Ex: A variable named count
indicates the variable's purpose better than a variable named c
.
Python has reserved words, known as keywords, which have special functions and cannot be used as names for variables (or other objects).
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Write a Python computer program that:
- Creates a variable,
team1
, assigned with the value"Liverpool"
. - Creates a variable,
team2
, assigned with the value"Chelsea"
. - Creates a variable
score1
, assigned with the value4
. - Creates a variable,
score2
, assigned with the value3
. - Prints
team1
,"versus"
, andteam2
as a single line of output. - Prints
"Final score: "
,score1
,"to"
,score2
as a single line of output.