A variable is like a container which is used to store a value. At times there is a need to store some data for future usage. A variable in python needs not to be declared before usage, it is created the moment you assign it a value.
a = 10 b = 'cat'
The print statement
To output the value contained by a variable, we use the print statement.
a = 10 b = 'cat' print(a) print(b)
The type statement
If you want to check the type of a variable, you can use the type statement.
a = 10 b = 'cat' print(type(a)) print(type(b))
This means the first variable is of integer type and variable named b is of string type.
In python, variables do not need to be declared with a particular data type. Even the type of a variable can be changed at any moment.
a = 7 # a is of type int a = 'car' # a is now of str type.
Note: Like other programming languages like C, C++ or Java, the value of a variable can be overwritten at any moment.
str variables can be declared by using either single or double quotes.
username = 'aman' #or username = "aman"
A variable can have a single character as name or even a word (for example- car, usernmae, age). There are some rules to create variables in python.
- A variable name cannot start with a number but can end with a number.
- A variable name must start with underscore(_) or a letter.
- Variable names in python are case sensitive (For example car and CAR are two different variables and not the same).
- A variable name can contain numbers(but not at the start), alphabets (a-z, A-Z) and underscores.
Some valid variable names
age = 21 username = 'pradeep' _address = 'sagar' myAddress = 'bhopal' ROLLNO = 1001 user1 = 'derek'
Some invalid variable names
1user = 'derek' #A variable name cannot contain start with a number. my-Address = 'bhopal' #A variable name cannot contain dashes(-). my Address = 'bhopal' #A variable name cannot contain spaces.
You can assign values to different variables separetely or in the same line.
Assigning values to variables separately-
a = 1 b = 4 c = 7 print(a) print(b) print(c)
Assigning values to different variables in the same line-
a, b, c = 1, 4, 7 print(a) print(b) print(c)
The output in either case will be-