Python Variable and Types
Python Variable and Types
Variables are named location to hold a value that can be used throughout the program. Name of the variables and functions are called as identifiers.
Note : 1. Comment in Python starts with # (hash) character.
2. In Python, there is no need to use semicolon(;) at the end of the statement.
Assigning Value to a variable
- In Python we do not need to declare a variable type.
- It happens automatically when you will assign value to a variable.
- Equal sign is used to assign value to a variable.
Below is the example of assigning values to variables:
[pastacode lang=”python” manual=”a%3D%20100%20%20%20%20%20%20%20%20%20%20%20%23a%20is%20integer%2C%20holds%20a%20value%20equal%20to%20100.%0Api%20%3D%203.14%20%20%20%20%20%20%20%20%23pi%20is%20float%0Astring1%3D%20%22I%20love%20programming%20in%20Python%22%20%20%20%23string1%20is%20a%20string%0Ax%3Dy%3Dz%3D%20100%20%20%20%20%20%20%20%20%20%20%20%23this%20statement%20assign%20100%20to%20z%2C%20y%20and%20x.%0Ap%2Cq%3D20%2C30%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%23It%20will%20assign%2020%20to%20p%20and%2030%20to%20q.%0A%0A” message=”” highlight=”” provider=”manual”/]
Python Variable Types
Python has various standard data types and can be divided into following types.
- Number
- String
- List
- Tuple
- Dictionary
- Sets
Number in Python
Used to store numeric values.It stores four different types of numeric values.
Integer (Int) : like 34, 2, 67 etc.
Long : like 355487L , -4875684L, 83647L etc.
Float : like 54.00, 76.46 etc
Complex : 3.14j, 56.j, .645j etc.
Number objects are created when you assign a value to them. To define different types of numeric values see below code for reference.
[pastacode lang=”python” manual=”intvalue%20%3D%20%208%20%20%20%23define%20an%20integer%20value%0Amyfloat%20%3D%204.36%20%20%20%23define%20a%20float%20value%0Afloatval%20%3D%20float(7)%0Aa%20%3D%2010%0Ab%20%3D%2020%0Ax%2C%20y%20%3D%208.5%2C%202.4%0Aprint(%22Sum%20of%20a%20and%20b%20is%20%3A%22)%0Aprint(a%20%2B%20b)%0Aprint(%22Division%20of%20x%20and%20y%20is%3A%22)%0Aprint(x%2Fy)” message=”” highlight=”” provider=”manual”/]
Output of above code is :
Sum of a and b is : 30 Division of x and y is: 3.541666666666667
String in Python
String in python are set of characters. In python it can be defined either by \Single quote or Double quote.
Plus(+) sign is used for concatenation of strings and Multiplication(*) sign is used for repetition.
Below is the example of defining string object in python.
[pastacode lang=”python” manual=”str1%20%3D%20%22Sam%22%20%20%20%23%20using%20double%20quotes%0Astr2%20%3D%20’Joseph’%20%20%23%20using%20single%20quotes%0Aprint(%22My%20Name%20is%20%22%20%2B%20str1%20%2B%22%20%22%20%2B%20str2)%0Aprint(%22you%20can%20call%20me%20%22%20%2B%20(str1%5B0%5D%20*%202))%20%20%20%23printing%201st%20character%20of%20str1%20two%20times%0Aprint(%22My%20short%20name%20is%20%22%20%2B%20(str1%5B0%5D%20%2B%20str2%5B0%5D))%20%20%23printing%201st%20character%20of%20str1%20and%20str2%20together.” message=”” highlight=”” provider=”manual”/]
Output of above program :
My Name is Sam Joseph you can call me SS My short name is SJ
List in Python
- It is the most famous data type of Python.
- It is somewhat similar to array in C-language , one major difference is list stores heterogeneous data while array stores similar type of data.
- A list contains items separated by comma(,) and enclosed in square bracket[]
- We use the slicing operator [ ] to extract an item or a range of items from a list.
- Index starts form 0 in Python.
- List are mutable means, values can be modified.
List Example
[pastacode lang=”python” manual=”mylist%20%3D%20%5B%5D%20%20%20%23%20creates%20a%20empty%20list%0Amylist.append(10)%20%20%20%23%20add%2010%20to%20the%20empty%20list%0Amylist.append(30.6)%20%23%20add%2030.6%20to%20mylist%0Amylist.append(%22python%22)%20%20%23%20add%20string%20python%20to%20mylist%0Aprint(mylist%5B0%5D)%20%23%20prints%2010%0Aprint(mylist%5B1%3A2%5D)%20%23%20prints%2030.6%20and%20python%0Aprint(mylist)%20%20%20%20%23%20prints%20the%20whole%20list%0A%0Afor%20x%20in%20mylist%3A%0A%20%20%20%20print%20(x)%20%20%20%20%20%20%20%20%20%20%23%20prints%20out%20all%20value%20of%20list%20one%20by%20one” message=”” highlight=”” provider=”manual”/]
Below is the Output of above code :
10 [30.6] [10, 30.6, 'python'] 10 30.6 python
Tuple in Python
- Tuple is very similar to List except its size is fixed, means we can not add or delete items from a Tuple.
- Hence Tuple is immutable sequence type.
Tuple Example
[pastacode lang=”python” manual=”tuple1%20%3D%20(%20%22John%22%2C007%2C2.23%2C%20’Bond’%2C%2070.2%20%20)%0Atuple2%20%3D%20(123%2C%20’python’)%0A%0Aprint%20tuple1%20%20%20%20%20%20%20%20%20%20%20%23%20Prints%20the%20whole%20list%0Aprint%20tuple1%5B0%5D%20%20%20%20%20%20%20%20%23%20Prints%20first%20element%20of%20the%20list%0Aprint%20tuple1%5B1%3A4%5D%20%20%20%20%20%20%23%20Prints%20elements%20starting%20from%202nd%20till%203rd%20%0Aprint%20tuple1%5B2%3A%5D%20%20%20%20%20%20%20%23%20Prints%20elements%20starting%20from%203rd%20element%0Aprint%20tuple2%20*%202%20%20%20%20%20%20%20%23%20Prints%20two%20times%0Aprint%20tuple1%20%2B%20tuple2%20%20%23%20Prints%20concatenated%20lists” message=”” highlight=”” provider=”manual”/]
Output of above program:
('John', 7, 2.23, 'Bond', 70.2) John (7, 2.23, 'Bond') (2.23, 'Bond', 70.2) (123, 'python', 123, 'python') ('John', 7, 2.23, 'Bond', 70.2, 123, 'python')
Dictionary in Python
- Dictionary in python stores values in key-value pairs.
- It is used to fast retrieve, add, remove and modify the values using the key.
- It is somewhat similar to associative array or Hashes.
- Dictionaries are enclosed by curly braces ({ }) and values can be assigned and accessed using square braces ([]).
Dictionary Example
[pastacode lang=”python” manual=”%23%20Create%20a%20dictionary.%0Adata%20%3D%20%7B%22a%22%3A%201%2C%20%22b%22%3A%202%2C%20%22c%22%3A%203%7D%0A%0A%23%20Loop%20over%20items%20and%20unpack%20each%20item.%0Afor%20k%2C%20v%20in%20data.items()%3A%0A%20%20%20%20%23%20Display%20key%20and%20value.%0A%20%20%20%20print(k%2C%20v)” message=”Program to create and display a dictionary” highlight=”” provider=”manual”/]
Hi Kundan,
Useful tutorial but in dictionary, please provide the example as well.
Yes sure…