Python Variables Flashcards
Variables are containers for storing __________.
data values
Python has no command for declaring a variable.
A variable is created the moment you first assign a _______ to it.
value
example:
x = 5
y = “John”
print(x)
print(y)
Variables do not need to be declared with any particular type, and can even ______ type after they have been set.
change
example:
x = 4 # x is of type int
x = “Sally” # x is now of type str
print(x)
If you want to specify the data type of a variable, this can be done with ________.
casting
example:
x = str(3) # x will be ‘3’
y = int(3) # y will be 3
z = float(3) # z will be 3.0
You can get the data type of a variable with the __________ function.
type() function
example:
x = 5
y = “John”
print(type(x))
print(type(y))
String variables can be declared either by using __________ or __________ quotes:
is the same as
single or double
example:
x = “John”
x = ‘John’
Variable names _____ case-sensitive.
are case-sensitive
example:
a = 4
A = “Sally”
#A will not overwrite a
A variable can have a ______ name (like x and y) or a more _________ name (age, carname, total_volume).
- short
- descriptive
Give the 5 Rules for Python variables.
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)
A variable name cannot be any of the Python keywords.
Give an example of Legal variable names.
example:
Legal variable names:
myvar = “John”
my_var = “John”
_my_var = “John”
myVar = “John”
MYVAR = “John”
myvar2 = “John”
Give an example of Illegal variable names.
Example
Illegal variable names:
2myvar = “John”
my-var = “John”
my var = “John”
Remember that variable names ________ case-sensitive
are
Variable names with more than one word can be difficult to read.
There are several techniques you can use to make them more readable.
Give the 3 ways.
Camel Case
Pascal Case
Snake Case
For Variable Names, if you use ______________, each word, except the first, starts with a capital letter.
Camel Case
example:
myVariableName = “John”
For Variable Names, if you use ______________, each word is separated by an underscore character:
Snake Case
example:
my_variable_name = “John”
For Variable Names, if you use ______________, each word starts with a capital letter.
Pascal Case
example:
MyVariableName = “John”
Python allows you to assign values to multiple variables in one ________.
line
example:
x, y, z = “Orange”, “Banana”, “Cherry”
print(x)
print(y)
print(z)
Python allows you to assign the same value to multiple variables in one line. True of False?
True.
Example:
x = y = z = “Orange”
print(x)
print(y)
print(z)
If you have a collection of values in a list, tuple etc. Python allows you to extract the values into variables. This is called _________.
unpacking
Example
Unpack a list:
fruits = [“apple”, “banana”, “cherry”]
x, y, z = fruits
print(x)
print(y)
print(z)
The Python _________ function is often used to output variables.
print()
Example:
x = “Python is awesome”
print(x)
In the print() function, you output multiple variables, separated by a __________.
comma
example:
x = “Python”
y = “is”
z = “awesome”
print(x, y, z)
You can also use the ___ operator to output multiple variables:
+
Example
x = “Python “
y = “is “
z = “awesome”
print(x + y + z)
Notice the space character after “Python “ and “is “, without them the result would be “Pythonisawesome”.
For numbers, the + character works as a ________________.
mathematical operator
Example
x = 5
y = 10
print(x + y)
In the print() function, when you try to combine a string and a number with the + operator, Python will give you ___________.
an error
Example
x = 5
y = “John”
print(x + y)
The best way to output multiple variables in the print() function is to separate them with _________, which even support different data types.
commas
Example
x = 5
y = “John”
print(x, y)
Variables that are created outside of a function (as in all of the examples in the previous pages) are known as _____________.
________________ can be used by everyone, both inside of functions and outside.
global variables
Example:
Create a variable outside of a function, and use it inside the function
x = “awesome”
def myfunc():
print(“Python is “ + x)
myfunc()
OUTPUT:
Python is awesome
If you create a variable with the same name inside a function, this variable will be ____, 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.
local
Example
Create a variable inside a function, with the same name as the global variable
x = “awesome”
def myfunc():
x = “fantastic”
print(“Python is “ + x)
myfunc()
print(“Python is “ + x)
OUTPUT:
Python is fantastic
Python is awesome
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 _________ keyword.
global
Example
If you use the global keyword, the variable belongs to the global scope:
def myfunc():
global x
x = “fantastic”
myfunc()
print(“Python is “ + x)
OUTPUT:
Python is fantastic
Also, use the _______ keyword if you want to change a global variable inside a function.
global
Example
To change the value of a global variable inside a function, refer to the variable by using the global keyword:
x = “awesome”
def myfunc():
global x
x = “fantastic”
myfunc()
print(“Python is “ + x)
OUTPUT:
Python is fantastic
