Variables

Question 1

Variables

Answer 1

Variables are containers for storing data values

Question 2

x = 5
y = "John"

Answer 2

print(x)
print(y)

Question 3

Casting a variable

Answer 3

If you want to specify the data type of a variable, this can be done with casting.

x = str(3) # x will be '3'
y = int(3) # y will be 3
z = float(3) # z will be 3.0

Question 4

Get the Type of varibale

Answer 4

Get the data type of a variable with the type() function.

x = 5
y = “John”
print(type(x))
print(type(y))

Question 5

String variables can be declared either by using single or double quotes

Answer 5

x = "John"
# is the same as
x = 'John'

Question 6

Case-Sensitive variables

Answer 6

Variable names are case-sensitive.

a = 4
A = "Sally"
#A will not overwrite a

Question 7

Rules for Python variables:

Answer 7

• A variable name must start with a letter or the underscore character
• A variable name cannot start with a number
• A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ )
• Variable names are case-sensitive (age, Age and AGE are three different variables)

Question 8

Variable name examples

Answer 8

• myvar = “John”
• my_var = “John”
• _my_var = “John”
• myVar = “John”
• MYVAR = “John”
• myvar2 = “John”

Question 9

Illegal variable names

Answer 9

• 2myvar = “John”
• my-var = “John”
• my var = “John”

Question 10

Camel Case variable name

Answer 10

Each word, except the first, starts with a capital letter:

myVariableName = “John”

Question 11

Pascal Case variable name

Answer 11

Each word starts with a capital letter:

MyVariableName = “John”

Question 12

Snake Case

Answer 12

my_variable_name = “John”

Question 13

Assign values to multiple variables in one line:

Answer 13

x, y, z = “Orange”, “Banana”, “Cherry”

• print(x)
• print(y)
• print(z)

Question 14

Assign the same value to multiple variables in one line:

Answer 14

x = y = z = “Orange”

• print(x)
• print(y)
• print(z)

Question 15

Unpacking variables is:

Answer 15

If you have a collection of values in a list, tuple etc. Python allows you extract the values into variables.

fruits = [“apple”, “banana”, “cherry”]

x, y, z = fruits

• print(x)
• print(y)
• print(z)

Question 16

This is:

fruits = [“apple”, “banana”, “cherry”]
x, y, z = fruits
print(x)
print(y)
print(z)

Answer 16

Unpacking variables

Question 17

Output variables

Answer 17

print() statement is often used to output variables.

x = “awesome”
print(“Python is “ + x)

Question 18

add a variable to another variable:

Answer 18

+ character to add a variable to another variable:

x = “Python is “
y = “awesome”
z = x + y
print(z)

Question 19

For numbers, the + character works as a:

Answer 19

Mathematical operator

x = 5
y = 10
print(x + y)

Question 20

If you try to combine a string and a number:

Answer 20

Python will give you an error:

x = 5
y = “John”
print(x + y)

Question 21

Can you combine a string and a number?

Answer 21

No, Python will give you an error.

x = 5
y = “John”
print(x + y)

Question 22

Global Variables

Answer 22

Variables that are created outside of a function.

x = "awesome"
def myfunc( ):
 print("Python is " + x)
myfunc( )

Question 23

If you create a variable with the same name inside a function, this variable will be local, and can only be used inside the function. The global variable with the same name will remain as it was, global and with the original value.

Answer 23

x = “awesome”

def myfunc():
 x = "fantastic"
 print("Python is " + x)

myfunc()

print(“Python is “ + x)

Question 24

Global Keyword

Answer 24

Normally, when you create a variable inside a function, that variable is local, and can only be used inside that function.

To create a global variable inside a function, you can use the global keyword.

def myfunc():
 global x
 x = "fantastic"
myfunc()
print("Python is " + x)

Question 25

Change a global variable inside a function

Answer 25

Use the global keyword

x = "awesome"
def myfunc():
 global x
 x = "fantastic"
myfunc()
print("Python is " + x)