# Day 2 of #100DaysOfPython

## Day 2

I have completed the day 2 challenge from the Udemy course. I took some notes from the lectures and decided to share them here as well.

I also started a new chapter from the book - *Think Python*. This chapter teaches me more about function. The exercises are a bit challenging for me. But it really taught me to break down the problem into smaller pieces as possible. From there we can build our solutions up more easily.

*Python for Everybody* has a lot similar in explaining the concepts, sometimes it is clearer. I prefer to read *Think Python* first and then read *Python for Everybody* as a revision. The exercises in each of these books vary as well. So it is a great opportunity for me to practice as many questions as possible.

## Leveling up

I can feel that the difficulty of the lessons started to level up although this is only the second day. This time, I want to build a strong foundation in this newly learned language, so I will be patient and learn it step-by-step and start to build projects after knowing all the basics of Python.

## Notes

- underscore between the digits represents the comma

    ```python
    large_number = 123_456_789 # Equals to 123,456,789
    ```

- cannot concatenate different type together

    ```python
    print('Hello' + 'Hooi Yan') # valid
    print('Hello' + 123) # invalid
    ```

- check the data type

    ```python
    my_name = 'Hooi Yan'
    my_number = 123

    type(my_name) # >>> class('str')
    type(my_number) # >>> class('int')
    ```

- convert different data types

    ```python
    my_name = 'Hooi Yan'
    my_age = 25
    my_gpa = 4.0

    new_age = str(my_age) # >>> '25'
    new_gpa = int(my_gpa) # >>> 4
    ```

- the type we get from `input()` method is string
- round the floating point number

    ```python
    round(2.6666666, 2)
    ```

- f-String

    ```python
    score = 0
    height = 1.8
    isWinning = True

    f"Your score is {score}, your height is {height}, your are winning is {isWinning}"
    ```

- floor division

    ```python
    first_result = 8 / 2 # normal division

    second_result = 8 // 3 # floor division
    ```

- invalid assignment will result NoneType

    ```python
    # This variable holds nothing, no value is actually assigned to the variable
    # Therefore, this variable is a NoneType
    total_bill = print(input('What is the total amount of bill? $'))

    # This variable will hold a type of string
    # Its data type is string
    # >>> <class 'str'>
    total_bill = input('What is the total amount of bill? $')
    ```