Variables are containers in which data values can be stored within the computer’s memory. They have a name, which is also referred to as an address.
| This is a box / container. In variable terms, we can give it a name/address called box. We can put things in the box. In programming, these things are called data values. |
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We can assign the data value books into the variable called box.
We use assignment operator = to assign the data value to the variable.
After assigning, we will have a box containing books.
By assigning a value into the box (variable), we can use the value multiple times by calling the box (variable), instead of retyping "books" (value).
| box = "books" | The string value "books" is assigned to the variable box |
| block_number = 72 | The number value 72 is assigned to (=) the variable block_number |
| street_01 = ‘Nanyang Ave’ | The string value ‘Nanyang Ave’ is assigned to the variable street_01 |
| myList = ["apples", "bananas", "cherries"] | The list of fruits are assigned to the bariable myList. |
Tip! - It is good practice to choose meaningful / descriptive names that reflect the variable’s content for easier identification when you or someone else revisits your codes. Which variable names would you choose?
1. Must start with a letter, or the underscore character.
2. Can only contain alpha-numeric characters and underscores.
3. Case-sensitive
4. Cannot contain hyphens.
5. Cannot start with a number.
6. Cannot use Python reserved words – these mean something in Python
| False | await | else | import | pass |
| None | break | except | in | raise |
| True | class | finally | is | return |
| and | continue | for | lambda | try |
| as | def | from | nonlocal | while |
| assert | del | global | not | with |
| async | elif | if | or | yield |
1. Create a variable called fruit, and store "apple" into the variable you created and print.
2. Are you able to print the following? Try it in your IDE.
| Questions | Can it run? | Changes |
|---|---|---|
| YEAR = 1995 | Yes | Nil |
| course_code = "DSE2020" | Yes | Nil |
| 01_street = ‘Nanyang Ave’ | No, variable names cannot begin with a number | street_01 = 'Nanyang Ave' |
| my-birth-year = 1982 | No, variable names cannot contain hyphens | my_birth_year = 1982 |