Commit 9a3fc1f9 authored by Chris's avatar Chris
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Completed Solidity intro part 5: Units

parent 7e00a767

Learn Solidity basics/Notes.md

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Covers getting started: using Remix, creating smart contracts



### Video link

### Part 1 video link



https://www.youtube.com/watch?v=sngKPYfUgkc&list=PLvfQp12V0hS2PQd9-X-E2AjmXj1o05WOo

<https://www.youtube.com/watch?v=sngKPYfUgkc&list=PLvfQp12V0hS2PQd9-X-E2AjmXj1o05WOo>



### Notes

### Part 1 notes



- Remix: allows you to write Solidity code; allows you to write, compile, and run the code on eth blockchain

  - remix.ethereum.org
@@ -35,11 +35,11 @@ contract SampleContract { 


Covers variable types



### Video link

### Part 2 video link



<https://www.youtube.com/watch?v=C70XrG5yGQo&list=PLvfQp12V0hS2PQd9-X-E2AjmXj1o05WOo&index=2>



### Notes

### Part 2 notes



- keep usage of strings to a minimum: strings are bytes bundled together, which means they can cost a lot of gas when used in smart contracts

  - keep usage of strings to a minimum and rely on primitve types instead
@@ -67,11 +67,11 @@ Covers variable types 


continuing usage of variables with more interesting concepts, covering the `address` type



### Video link

### Part 3 video link



https://www.youtube.com/watch?v=AFma5JYgIIE&list=PLvfQp12V0hS2PQd9-X-E2AjmXj1o05WOo&index=4

<https://www.youtube.com/watch?v=AFma5JYgIIE&list=PLvfQp12V0hS2PQd9-X-E2AjmXj1o05WOo&index=4>



### Notes

### Part 3 notes



- address types were created, but they should properly be typecasted (are they really primitives then...?)

  - `address public myAddress = address(...)`
@@ -104,11 +104,47 @@ https://www.youtube.com/watch?v=AFma5JYgIIE&list=PLvfQp12V0hS2PQd9-X-E2AjmXj1o05 


this tutorial talks about operators you can use in Solidity



### Video link

### Part 4 video link



https://www.youtube.com/watch?v=KlO23rhqEnw&list=PLvfQp12V0hS2PQd9-X-E2AjmXj1o05WOo&index=5

<https://www.youtube.com/watch?v=KlO23rhqEnw&list=PLvfQp12V0hS2PQd9-X-E2AjmXj1o05WOo&index=5>



### Notes

### Part 4 notes



- see **MyOperators.sol** for a list of operators you can use

- a **view function** is a function that does not change state: use keyword to help compiler and readability



## Part 5



this tutorial talks about measurement units (wei, gwei, ether) available in Solidity



### Part 5 video link



<https://www.youtube.com/watch?v=64SiCO_GzDo&list=PLvfQp12V0hS2PQd9-X-E2AjmXj1o05WOo&index=6>



### Part 5 notes



- smart contracts always work with the unit **wei**

  - review:

    - 1 wei == 1

    - 1 gwei == 1e9

    - 1 ether == 1e18

- so you can actually just do this:



```solidity

uint256 costOfNFT = 0.05 ether;

```



- you also get units with time

  - 1 == 1 seconds

  - 1 minutes == 60 seconds

  - 1 hours == 60 minutes

  - 1 days == 24 hours

  - 1 weeks == 7 days



- let's talk about gas

- gas is the unit of computation in Solidity

  - the unit of computation on the Ethereum blockchain

- gas price is defined as the amount you are willing to pay for a gas unit

- price of the gas is usually set, and the higher the gas price, the higher priority it will be to be mined first

  - higher the gas price -> higher the tx fee, and the quicker it gets mined on the block

- the gas spent is usually on the transaction: how long it took for the contract to run through the program and execute what it needed to execute