Solidity completed part 7 (ba380127) · Commits · Chris / Solidity NFT learning

Learn Solidity basics/Notes.md

+20 −1

Original line number	Diff line number	Diff line
		@@ -190,6 +190,7 @@ uint256 costOfNFT = 0.05 ether;
		- Solidity gives us the saame familiar if/else statements and for/while loops as you see in other languages
		- this section covers enums, arrays, mappings
		- lots of good information on how minting works by mutating the contract's state
		- lots of examples: check the related .sol files

		## Part 7

		@@ -200,10 +201,28 @@ uint256 costOfNFT = 0.05 ether;
		### Part 7 related .sol files

		- [MyStructs.sol](./contracts/MyStructs.sol)
		- [MyFunctions.sol](./contracts/MyFunctions.sol)

		### Part 7 notes

		- todo fill this out
		- shows how to create structs in Solidity
		- when you are working with variables, there is the `memory` keyword and the `storage` keyword that can be used
		- this seems to be separate from how scope works
		- `memory` is when something can be disposed of after the contract execution is complete
		- `storage` is when a variable should be stored on the blockchain
		- section covers structs and data locations
		- what are data locations?
		- everything that is stored on the blockchain has storage somewhere
		- three different data locations: storage, memory, and calldata
		- storage data would be anything stored on the blockchain. state variables
		- memory data would be anything ephemeral, it's needed for functionality but it doesn't have to remain on the blockchain
		- calldata data is good when you are adding a list of objects
		- primitive types don't need memory/storage keywords
		- "pure" function means a function that doesn't mutate any data on the blockchain
		- Solidity compiler creates what is called an ABI to index function signatures
		- view functions depend on data from outside of the function
		- in Remix, when looking at a deployed smart contract, the orange buttons cost gas and the blue ones do not
		- there is another scope for functions, `external`, that can only be called from outside of the contract

		## Part 8

Learn Solidity basics/contracts/MyFunctions.sol

0 → 100644

+29 −0

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: MIT

		pragma solidity ^0.8.0;

		contract MyFunctions {
		// state/storage variables
		uint256 myUint = 42;
		string myString = "Daniel";
		bool myBool = true;
		uint256[] myArr = [3, 3, 3];

		function myPureFunc(uint256 _x, uint256 _y) pure public returns (uint256 xy) {
		return _x + _y;
		}

		function myViewFunc() view private returns (string memory) {
		return myString;
		}

		function myUpdateFunc() external returns (string memory) {
		myString = "HashLips";
		string memory savedString = myViewFunc();
		return savedString;
		}

		function myReturnsFunc() view external returns (uint256, string memory, bool, uint256[] memory) {
		return (myUint, myString, myBool, myArr);
		}
		}
		No newline at end of file

Learn Solidity basics/contracts/MyStructs.sol

0 → 100644

+58 −0

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: MIT

		pragma solidity ^0.8.0;

		contract MyStructs {
		struct NFT {
		string name;
		uint256 dna; // <-- what is dna??
		}

		mapping(uint256 => NFT) nftMapping; // this isn't used in this contract, but this is how you make a mapping to struct values
		NFT[] public nftList;

		function addNFT(string memory _name, uint256 _dna) public {
		// commented out is the long way to create an NFT object
		// NFT memory newNFT;
		// newNFT.name = _name;
		// newNFT.dna = _dna;

		// nftList.push(newNFT);

		// here is a better way:
		NFT memory newNFT = NFT(_name, _dna);
		nftList.push(newNFT);
		}

		function addNFTs(NFT[] calldata _nfts) public {
		for (uint256 i = 0; i < _nfts.length; i++) {
		NFT memory newNFT = _nfts[i];
		nftList.push(newNFT);
		}
		}

		function updateNFTStorage(uint256 _index, string memory _newName) public {
		NFT storage nftToBeUpdated = nftList[_index]; // so this is essentially creating a pointer
		// if you used memory here instead, it would create a new NFT object in memory that you would have to push to the array
		// (see updateNFTMemory)
		nftToBeUpdated.name = _newName;
		}

		function updateNFTMemory(uint256 _index, string memory _newName) public {
		NFT memory nftToBeUpdated = nftList[_index];
		nftToBeUpdated.name = _newName;
		nftList[_index] = nftToBeUpdated;
		}

		function getNFT(uint256 _index) public view returns(NFT memory) {
		return nftList[_index];
		}

		function getNFTName(uint256 _index) public view returns(string memory) {
		return nftList[_index].name;
		}

		function myNoReturnFunc() external {
		myBool = false;
		}
		}
		No newline at end of file