====== Python Cheatsheet ======

===== Basic Syntax =====
  * **Variables:** Variables do not need explicit declaration.
    ```python
    x = 5
    name = "John"
    ```

  * **Comments:**
    ```python
    # This is a single-line comment

    """
    This is a
    multi-line comment
    """
    ```

===== Data Types =====
  * **Common Types:**
    * int: `x = 10`
    * float: `y = 3.14`
    * str: `text = "Hello"`
    * list: `lst = [1, 2, 3]`
    * tuple: `tup = (1, 2, 3)`
    * dict: `d = {"key": "value"}`
    * bool: `flag = True`

===== Control Flow =====
  * **If-else statement:**
    ```python
    if x > 5:
        print("x is greater than 5")
    elif x == 5:
        print("x is 5")
    else:
        print("x is less than 5")
    ```

  * **Loops:**
    * **For loop:**
      ```python
      for i in range(5):
          print(i)
      ```

    * **While loop:**
      ```python
      count = 0
      while count < 5:
          print(count)
          count += 1
      ```

===== Functions =====
  * **Defining a function:**
    ```python
    def greet(name):
        return f"Hello, {name}"
    ```

  * **Lambda Functions:**
    ```python
    add = lambda x, y: x + y
    print(add(2, 3))
    ```

===== Data Structures =====
  * **List methods:**
    ```python
    lst = [1, 2, 3]
    lst.append(4)
    lst.remove(2)
    print(lst)
    ```

  * **Dictionary methods:**
    ```python
    d = {"name": "Alice", "age": 25}
    print(d["name"])
    d["age"] = 26
    ```

===== Exceptions =====
  * **Try-Except Block:**
    ```python
    try:
        result = 10 / 0
    except ZeroDivisionError:
        print("Cannot divide by zero")
    finally:
        print("End of try-except block")
    ```

===== File Handling =====
  * **Reading a file:**
    ```python
    with open("file.txt", "r") as file:
        content = file.read()
    print(content)
    ```

  * **Writing to a file:**
    ```python
    with open("file.txt", "w") as file:
        file.write("Hello, World!")
    ```

===== Modules =====
  * **Importing a module:**
    ```python
    import math
    print(math.sqrt(16))
    ```

  * **Custom module:**
    ```python
    # In mymodule.py
    def add(x, y):
        return x + y

    # In main file
    from mymodule import add
    print(add(3, 4))
    ```

===== Classes & Objects =====
  * **Defining a class:**
    ```python
    class Person:
        def __init__(self, name, age):
            self.name = name
            self.age = age

        def greet(self):
            print(f"Hello, my name is {self.name}")

    p = Person("Alice", 25)
    p.greet()
    ```

===== Common Built-in Functions =====
  * **Range:** `range(5)` generates numbers 0 to 4.
  * **Len:** `len(lst)` returns the length of a list.
  * **Type:** `type(x)` returns the data type of `x`.
  * **Input:** `input("Enter your name: ")` takes user input.

===== Useful Tips =====
  * **List comprehensions:**
    ```python
    squares = [x**2 for x in range(5)]
    print(squares)
    ```

  * **Unpacking:**
    ```python
    a, b = 1, 2
    print(a, b)
    ```

===== Conclusion =====
This cheatsheet covers the basics of Python syntax and essential concepts for quick reference. For more details, refer to the official Python documentation.