Master Python Basics: Data Types, Strings, and Arithmetic Explained

1 Python Features

Python is an interpreted, general‑purpose programming language; code is executed line by line.

It supports object‑oriented concepts such as classes and objects.

It is dynamically typed, meaning variable types are determined at runtime.

2 Data Types

String (text) type: "hello world" , 'hello world' , '1' – any characters enclosed in single or double quotes.

Numeric types: integers ( int ) like 1 , 25 , 100000 ; floating‑point ( float ) like 1.0 , 25.1 , 1000.0001 .

Sequence types: list [1,2,3,5,9] , tuple (2,4,6,8) , range range(1,20) (produces numbers 1‑19).

Mapping type: dictionary {'a':1,'b':2} where keys and values are separated by a colon.

Boolean type: True or False .

Set type: {1,2,3,4} – unordered, unique elements, defined with curly braces without colons.

2.1 Viewing Data Types

<code>type('hello world')
str
type(1)
int
type([1,2])
list</code>

2.2 Converting Data Types

Convert number to string:

<code>str(20)
'20'</code>

Convert numeric string to float:

<code>float('123')
123.0</code>

2.3 Displaying Data

Use print() to output values:

<code>print('hello world')
print(1, 'hello', 2)
print((1,3,5))</code>

2.4 Variable Assignment

Assign with = :

<code>age = 10
age
10</code>

Multiple assignment:

<code>a,b,c = 1, True, [3,4]
a
1
c
[3,4]</code>

Chained assignment:

<code>c = d = e = 10
c
10
e
10</code>

Note: Variable names cannot contain spaces or start with a digit; use underscores for multi‑word names, e.g., my_name .

3 String Operations

3.1 Creating Strings

<code>name = 'xiaoming'
name1 = "xiaoming"</code>

Both single and double quotes are valid; be consistent.

3.2 Indexing

Python uses zero‑based indexing; -1 accesses the last element.

<code>a = 'hello world'
a[0]   # 'h'
a[3]   # 'l'
a[-1]  # 'd'</code>

3.3 Length

Use len() to get the number of characters:

<code>len('hello world')
11</code>

3.4 Concatenation

Use + to join strings and * to repeat:

<code>'hello world' + '!'
'hello world!'
'hello world' * 3
'hello worldhello worldhello world'</code>

4 Numeric Operations

Python supports standard arithmetic operators: + addition, - subtraction, * multiplication, / division, // floor division, ** exponentiation, and % modulus.

<code>4 + 9   # 13
4 - 9   # -5
4 * 9   # 36
4 / 9   # 0.444...
4 // 9  # 0
4 % 9   # 4
4 ** 9  # 262144</code>

Beginners can treat Python as a calculator.

5 Summary

This article briefly introduced Python's data types, focusing on strings and numeric operations.