2.1.4.11 SECTION SUMMARY

Key takeaways

1. A variable is a named location reserved to store values in the memory. A variable is created or initialized automatically when you assign a value to it for the first time. (2.1.4.1)

2. Each variable must have a unique name - an identifier. A legal identifier name must be a non-empty sequence of characters, must begin with the underscore(_), or a letter, and it cannot be a Python keyword. The first character may be followed by underscores, letters, and digits. Identifiers in Python are case-sensitive. (2.1.4.1)

3. Python is a dynamically-typed language, which means you don't need to declarevariables in it. (2.1.4.3) To assign values to variables, you can use a simple assignment operator in the form of the equal (=) sign, i.e., var = 1.

4. You can also use compound assignment operators (shortcut operators) to modify values assigned to variables, e.g., var += 1, or var /= 5 * 2. (2.1.4.8)

5. You can assign new values to already existing variables using the assignment operator or one of the compound operators, e.g.: (2.1.4.5)

var = 2 print(var) var = 3 print(var) var += 1 print(var)

6. You can combine text and variables using the + operator, and use the print()function to output strings and variables, e.g.: (2.1.4.4)

var = "007" print("Agent " + var)

Exercise 1

What is the output of the following snippet?

var = 2 var = 3 print(var)
 

Exercise 2

Which of the following variable names are illegal in Python?

my_var m 101 averylongvariablename m101 m 101 Del del
 

Exercise 3

What is the output of the following snippet?

a = '1' b = "1" print(a + b)