Data types in Python

A data type represents the type of data stored into a variable or memory. There are five main data types:

Numeric
String
List
Tuple
Dictionary

Note – Variables are the address in the memory where the values are stored. We can treat variable like a container where you can put or store something.

Numeric Data Type

The numeric data types are used to represent numbers. There are three sub data types:

int
float
complex

Int data type

The int data type represents an integer number. An integer number are a number without any decimal point or fraction part. For example 200, -100, 67, 100000, etc. Integer uses 4 bytes to store a value. It can range from -2147483648 to 2147483647.

Float data type

The float data type represents floating point numbers. A floating point number is a number that contains a decimal point. Like 3.14, 34.45, -45.678, etc. Float uses 8 bytes to store a value. It can range from 2.3E-308 to 1.7E+308.

Complex data type

The complex data type is a number written in the form of a + bj, where a and b is a real number and j is an imaginary number.

String

A string is a sequence of characters. A character is simply a symbol. For example, the English language has 26 characters. Computers do not deal with characters, they deal with binary numbers. Characters are stored internally and manipulated as a combination of 0’s and 1’s. this conversion of a character to a number is called encoding, and the reverse process is called decoding.

String is encoded in two ways: ASCII and Unicode.

Special String operators

Assume, string variable a holds ‘Hello’ and variable b holds ‘Python’, then

Operator	Description	Example
+	Concatenation – Adds values on either side of the operator.	a + b will give: HelloPython. a + “ “ + b will give Hello Python
*	Repetition – Creates new strings by concatenating multiple copies of the same string.	*a 2** will give: HelloHello
[ ]	Slice – Gives the character from the given index.	a[1] will give: e (second character in ‘Hello’)
[ : ]	Range – Gives the characters from the given range.	a[1:4] will give: Will give ell (Element at position 4 is not included)
in	Membership – Returns true if a character exists in the given string.	H in a will give : 1 or True

List Data Type

List in Python are similar to arrays in C or Java. A list represent a group of elements. The main difference between a list and array is that a list can store different type of elements, but an array can store only one type of elements. Also list can grow dynamically in memory. The size of array is fixed and they cannot grow at runtime. List are represented using square brackets [ ] and the element are written in [ ], separated by commas.

E.g. Listeg = [10,-15,15.67,’ajit’]

We can use the index operator [ ] to access an item in a list. Index start from 0. Means a list having 5 elements will have the index 0 to 4.

Example:-

listeg = ['a', 'b', 'c', 6, 8, 10]

print("All items in list:", listeg)

print("First element",listeg[0])

print("Last element",listeg[5])

print('c' in listeg)

Output:-

All items in list: ['a', 'b', 'c', 6, 8, 10]

First element a

Last element 10

True

Tuple Data Type

A tuple is like a list. The difference between two is that we cannot change the elements of a tuple, once it is assigned whereas in a list, elements can be changed. This represents tuple can be treated as read-only list. The list items are written under square bracket [ ] while, tuples are written under parenthesis bracket ( ).

Example:-

#following statement represents tuple

thistuple = ("apple", "banana", "cherry")

print(thistuple)

#following statement represents list

thistuple1 = ["kiwi"]

thistuple1.append("mango")

print(thistuple1)

Output:-

('apple', 'banana', 'cherry')

['kiwi', 'mango']

Dictionary Data Type

A dictionary is an unordered collection of items arranged in the form of ‘key:value’ pair. The elements in the dictionary are placed under curly braces { }. An item has a key and its value is separated by a colon.

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