diff --git a/python.md b/python.md index 816c53f..52fd2f1 100644 --- a/python.md +++ b/python.md @@ -1,180 +1,218 @@ # Python Cheat Sheet -## Variables and Data Types +## Table of Contents -### Variables +1. [Variables](#variables) +2. [Data Types](#data-types) +3. [Operators](#operators) +4. [Control Structures](#control-structures) +5. [Functions](#functions) +6. [Lists](#lists) +7. [Strings](#strings) +8. [Dictionaries](#dictionaries) +9. [Tuples](#tuples) +10. [Sets](#sets) +11. [File Handling](#file-handling) +12. [Exception Handling](#exception-handling) +13. [Classes and Objects](#classes-and-objects) -#### Declaring a variable -``` -x = 5 -``` -#### Reassigning a variable -``` -x = 10 -``` -### Data Types +## Variables -#### Integer -``` -x = 5 -``` -#### Float -``` -x = 5.0 +### Declaration and Assignment +```python +variable_name = value ``` -#### Boolean -``` -x = True -``` +### Variable Types +- String: `string_variable = "Hello"` +- Integer: `int_variable = 42` +- Float: `float_variable = 3.14` +- Boolean: `bool_variable = True` -#### String -``` -x = "Hello, World!" -``` +## Data Types + +### Basic Types +- String +- Integer +- Float +- Boolean + +### Compound Types +- List +- Tuple +- Set +- Dictionary ## Operators -#### Arithmetic Operators -``` -+, -, *, /, %, ** +### Arithmetic Operators +```python ++, -, *, /, %, ** (exponentiation), // ``` -#### Comparison Operators -``` -==, !=, >, <, >=, <= +### Comparison Operators +```python +==, !=, <, >, <=, >= ``` -#### Logical Operators -``` +### Logical Operators +```python and, or, not ``` +### Assignment Operators +```python +=, +=, -=, *=, /=, %= +``` + ## Control Structures -### Conditional Statements - -#### If statement -``` -if x > 5: - print("x is greater than 5") -elif x == 5: - print("x is equal to 5") +### If Statement +```python +if condition: + # code to be executed if the condition is true +elif another_condition: + # code to be executed if the previous condition was false and this one is true else: - print("x is less than 5") -``` -### Loops - -#### For loop -``` -for i in range(0, 5): - print(i) + # code to be executed if all conditions are false ``` -#### While loop +### For Loop +```python +for i in range(5): + # code to be executed in each iteration ``` -i = 0 -while i < 5: - print(i) - i += 1 + +### While Loop +```python +while condition: + # code to be executed as long as the condition is true ``` ## Functions -#### Defining a function +### Function Declaration +```python +def function_name(param1, param2): + # code to be executed + return result # optional ``` -def my_function(param1, param2): - print(param1 + param2) -``` -#### Calling a function -``` -my_function(5, 10) + +### Function Call +```python +result = function_name(arg1, arg2) ``` ## Lists -#### Declaring a list -``` -my_list = [1, 2, 3, 4, 5] -``` -#### Accessing elements of a list -``` -my_list[0] # returns 1 -my_list[-1] # returns 5 +### List Declaration +```python +my_list = [1, 2, 3, "hello", True] ``` -#### Slicing a list -``` -my_list[1:3] # returns [2, 3] +### List Operations +```python +my_list.append(4) # Add an element to the end +my_list.remove("hello") # Remove a specific element ``` -#### Appending to a list -``` -my_list.append(6) +## Strings + +### String Concatenation +```python +string1 = "Hello" +string2 = "World" +concatenated = string1 + " " + string2 ``` -#### Removing from a list -``` -my_list.remove(2) +### String Methods +```python +len(my_string) # Length of the string +my_string.find("find") # Index of the first occurrence of "find" +my_string.split(",") # Split the string into a list ``` ## Dictionaries -#### Declaring a dictionary -``` +### Dictionary Declaration +```python my_dict = {"key1": "value1", "key2": "value2"} ``` -#### Accessing elements of a dictionary -``` -my_dict["key1"] # returns "value1" +### Dictionary Operations +```python +my_dict["new_key"] = "new_value" # Add a new key-value pair +del my_dict["key1"] # Remove a key-value pair ``` -#### Adding to a dictionary -``` -my_dict["key3"] = "value3" +## Tuples + +### Tuple Declaration +```python +my_tuple = (1, 2, 3, "hello", True) ``` -#### Removing from a dictionary -``` -del my_dict["key2"] +### Immutable Nature +```python +# Tuple elements cannot be changed once set +my_tuple[0] = 4 # This will result in an error ``` -## Classes +## Sets -#### Declaring a class -``` -class MyClass: - def __init__(self, param1, param2): - self.param1 = param1 - self.param2 = param2 - - def my_method(self): - print(self.param1 + self.param2) +### Set Declaration +```python +my_set = {1, 2, 3, 3, 4} ``` -#### Creating an instance of a class -``` -my_instance = MyClass(5, 10) +### Set Operations +```python +my_set.add(5) # Add an element to the set +my_set.remove(3) # Remove an element from the set ``` -#### Calling a method of a class -``` -my_instance.my_method() +## File Handling + +### Reading from a File +```python +with open("filename.txt", "r") as file: + file_content = file.read() ``` -## Exceptions - -#### Catching an exception +### Writing to a File +```python +with open("filename.txt", "w") as file: + file.write("Hello, World!") ``` + +## Exception Handling + +### Try-Except Block +```python try: - # some code that may raise an exception -except ExceptionType: - # do something to handle the exception + # code that may raise an exception +except Exception as e: + # handle the exception + print("Error:", e) +``` + +## Classes and Objects + +### Class Declaration +```python +class MyClass: + def __init__(self, name): + self.name = name + + def say_hello(self): + print(f"Hello, {self.name}!") +``` + +### Object Instantiation +```python +obj = MyClass("John") +obj.say_hello() # Outputs: Hello, John! ``` -#### Raising an exception -``` -raise ExceptionType("Error message") ```