Updated with casting and error handling

tutorial-reference/Day 2/Day 2 - Numbers, Variables, and Operators.md

@@ -0,0 +1,187 @@
+# Day 2 - Variables, Data Types and Operators
+This tutorial is based on variables, data types and operators
+
+## Variables
+A variable holds a value in a memory location that is needed for the execution of your program.
+
+### Using a variable
+A memory location needs to be allocated for the variable value, before it can be used by the program.
+
+**Declaring a variable** means stating what _data type_ will be used for the value. 
+**Initialising a variable** means _setting the initial value_. Python doesn’t use variable declaration, only initialisation.
+
+**Example**
+```python
+name = "Alex"
+print(name)
+```
+
+## Data Types
+There are five main data types namely;
+- String (text) e.g "Alex", "Sofia"
+- Integer (whole numbers) e.g. 3, 4, 5
+- Boolean (True or False) e.g. True, False
+- Real or floating point numbers (decimal numbers) e.g. 4.5, 7.54
+- Char (single string characters) e.g. "a", "z", "b"
+
+**N.B:** Incorrect data types can cause problems during the execution of your programs.
+
+**Question**
+
+Predict what might happen when this code is executed.
+
+```python
+print("Enter a number")
+num1 = input()
+print("Enter another number")
+num2 = input()
+print(num1+num2)
+```
+**Output**
+```bash
+Enter a number
+1
+Enter another number
+2
+12
+>>>
+```
+The data type for an input is always string. When you add two pieces of string together, it will concatenate (join) them. 
+Instead of adding the two numbers together to make 3, it has joined the corresponding strings together to make 12 (one,two). 
+This code has produced a logic error because it hasn’t executed as expected.
+
+If you want Python to use your value as an integer, then you need to tell it that by **casting the value**. 
+You do this by placing `input()` inside the `int()` function.
+
+```python
+print("Enter a number")
+num1 = int(input())
+print("Enter another number")
+num2 = int(input())
+print(num1+num2)
+```
+
+```bash
+Enter a number
+1
+Enter another number
+2
+3
+```
+
+Errors can still happen during execution, even when casting has been used.
+ **Question**
+
+What might happen if the user enters ‘four’ when this code is executed?
+
+**Answer**
+
+A runtime error occurs. This is a type of error that causes the program to crash during execution.
+
+```python
+print("Enter a number")
+number = int(input())
+print(number)
+```
+
+```bash
+Enter a number
+four
+Traceback (most recent call last):
+  File "c:\users\pi\mu_code\fsea.py", line 2, in <module>
+    number = int(input())
+ValueError: invalid literal for int() with base 10: 'four'
+>>>
+```
+
+You can avoid this type of error by introducing validation checks. 
+Here is an example check that you can use called try and except. 
+
+```python
+print("Enter a number")
+try:
+    number = int(input())
+except ValueError:
+    print("You must enter a number")
+    number = int(input())
+```
+To convert values to different data types, you need to know the functions that are available to you. 
+Here are the most common functions that you will need to know.
+
+```python
+# convert to string
+str() 
+# convert to integer
+int()
+# convert to real
+float()
+```
+
+## Using Operators in Python
+Here are the list of operators in python;
+- (+)	Addition
+```python
+5 + 5
+```
+`>>> 10`
+
+- (-) 	Subtraction
+```python
+10 - 5
+```
+`>>> 5`
+
+- (*)	Multiplication
+```python
+5 * 5
+```
+`>>> 25`
+
+- / 	Real division
+```python
+5 / 2
+```
+`>>> 2.5`
+
+- //	Integer division (quotient) is the operation that calculates how many whole times the divisor (3) will fit in the dividend (14).
+```python
+26 // 5
+```
+`>>> 5`
+
+- **	Powers
+ ```python
+5 ** 2
+```
+`>>> 25`
+
+- %	Modulo (MOD) is used to work out the remainder of the division.
+```python
+15 % 7
+```
+`>>> 1`
+
+**Projects**
+- **Hello Python**
+  Create a script to print hello 🐍.
+
+  ```python
+  pi = "🐍"
+  print("Hello", pi)
+  ```
+
+- **Short Intro**
+  Create a program to introduce someone.
+
+  ```python
+  name = "Albert Einstein"
+  age = 67
+  profession = "Scientist"
+
+  print("Hello!", name, "is", age, "years old and a", profession)
+  ```
+
+
+
+
+

tutorial-reference/Day 3/Day 3 - Lists & Dictionaries.md

@@ -1,87 +1,49 @@
-Day 3 - Lists & Dictionaiers
+Mastering lists and dictionaries in Python involves understanding their functionalities, properties, and common operations. Here's a comprehensive breakdown to get you started:
 
-Code https://github.com/codingforentrepreneurs/30-days-of-python
-github: cfe.sh/github
+**Lists:**
 
-## Reference
-_Coming soon_
-
-__Declare__
-```
-my_list = []
+* **Definition:** An ordered collection of items enclosed in square brackets `[]`. Elements can be of any data type, including other lists and dictionaries.
+* **Creation:**
+```python
+my_list = [1, "hello", 3.14, [True, False]]
 ```
-or
+* **Accessing elements:** Use zero-based indexing starting from `[0]`. Negative indices access from the end (`[-1]` is the last element).
+```python
+first_element = my_list[0]  # first_element will be 1
+last_element = my_list[-1]  # last_element will be [True, False]
 ```
-my_list = [1, 2, 3, 4, 5]
+* **Slicing:** Extract a sublist using colon (`:`) notation. `[start:end:step]`:
+  * `start` (inclusive): index of the first element to include (defaults to 0).
+  * `end` (exclusive): index of the element after the last element to include (defaults to the end of the list).
+  * `step`: the difference between consecutive elements to include (defaults to 1).
+```python
+sublist = my_list[1:3]  # sublist will be ["hello", 3.14]
 ```
+* **Common operations:**
+  * `append(element)`: Add an element to the end of the list.
+  * `insert(index, element)`: Insert an element at a specific index.
+  * `remove(element)`: Remove the first occurrence of an element.
+  * `pop(index)`: Remove and return the element at a specific index (or the last element by default).
+  * `len(list)`: Get the length of the list (number of elements).
+  * `sort()`: Sort the list in ascending order (modifies the original list).
+  * `reversed()`: Return a reversed iterator for the list (doesn't modify the original list).
 
+**Dictionaries:**
 
-### Lists
+* **Definition:** An unordered collection of key-value pairs enclosed in curly braces `{}`. Keys must be unique and immutable (e.g., strings, numbers, tuples), while values can be any data type.
+* **Creation:**
 ```python
->>> my_cart = [12.99, 312, 32, 142]
->>> sum(my_cart)
-498.99
->>> my_cart.append(39.99)
->>> print(my_cart)
-[12.99, 312, 32, 142, 39.99]
->>> len(my_cart)
-5
->>> my_cart
-[12.99, 312, 32, 142, 39.99]
->>> my_cart[3]
-142
->>> my_cart[2]
-32
->>> my_cart[2] * 120
-3840
->>> my_string = "hello world"
->>> len(my_string)
-11
->>> my_string[4]
-'o'
-
->>> my_cart
-[12.99, 312, 32, 142, 39.99]
->>> my_items = ["mouse", "laptop", "mic", "screen", "snack"]
->>> my_items
-['mouse', 'laptop', 'mic', 'screen', 'snack']
->>> my_cart[1]
-312
->>> my_items[1]
-'laptop'
->>> my_products = [my_items, my_cart]
->>> my_products
-[['mouse', 'laptop', 'mic', 'screen', 'snack'], [12.99, 312, 32, 142, 39.99]]
->>> 
+my_dict = {"name": "Alice", "age": 30, "hobbies": ["reading", "hiking"]}
 ```
-
-### Dictionaries
+* **Accessing elements:** Use the key enclosed in square brackets `[]` to access the corresponding value.
 ```python
->>> my_list = [1,2,3,4,5]
->>> my_data = {"name": "Justin Mitchel"}
->>> my_data["name"]
-'Justin Mitchel'
->>> my_data = {"name": "Justin Mitchel", "location": "California"}
->>> my_data[0]
-Traceback (most recent call last):
-  File "<stdin>", line 1, in <module>
-KeyError: 0
->>> my_data.keys()
-dict_keys(['name', 'location'])
->>> list(my_data.keys())
-['name', 'location']
->>> list(my_data.keys())[0]
-'name'
->>> my_data.append({"occ": "coder"})
-Traceback (most recent call last):
-  File "<stdin>", line 1, in <module>
-AttributeError: 'dict' object has no attribute 'append'
->>> my_data["occ"] = "Coder"
->>> my_data
-{'name': 'Justin Mitchel', 'location': 'California', 'occ': 'Coder'}
->>> user_1 = {"name": "James bond"}
->>> user_2 = {"name": "Ned Stark"}
->>> my_users = [user_1, user_2]
->>> my_users
-[{'name': 'James bond'}, {'name': 'Ned Stark'}]
-```
+name = my_dict["name"]  # name will be "Alice"
+```
+* **Common operations:**
+  * `get(key, default)`: Get the value for a key, returning `default` if the key is not found.
+  * `keys()`: Return a view of all keys in the dictionary.
+  * `values()`: Return a view of all values in the dictionary.
+  * `items()`: Return a view of all key-value pairs as tuples.
+  * `in`: Check if a key exists in the dictionary.
+  * `update(dict2)`: Update the dictionary with key-value pairs from another dictionary (`dict2`).
+  * `pop(key, default)`: Remove the key-value pair and return the value, or `default` if the key is not found.