66 lines
1.7 KiB
Solidity
66 lines
1.7 KiB
Solidity
// SPDX-License-Identifier: MIT
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pragma solidity ^0.8.8;
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contract SimpleStorage {
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// boolean, uint, int, address, bytes
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address public myAddress = 0xc9445E993dAeA4bA3F1FE1080F0F6f8c46b4d967;
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uint256 public myNumber = 123; // With Getter, Retrieval Need Gas
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string myText = "Hello World";
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//int256 favoriteInt = -5;
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//bytes32 favoriteBytes = "cat";
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uint256 myDefaultZero; // Initialize default to 0
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// Paid
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function storeMyNumber(uint256 _favoriteNumber) public virtual {
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myNumber = _favoriteNumber;
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//retrieve();
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}
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/*
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view - for retrieve variable data (Free)
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pure - for calculation (Free)
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Free function will cost $ if call in Paid function
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*/
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function viewMyNumber() public view returns (uint256) {
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return myNumber;
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}
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function pureCalculation() public pure returns (uint256) {
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return ((1 + 555) * 22) / 88;
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}
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// Custom People Object
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struct People {
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uint256 favoriteNumber;
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string name;
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}
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People public personJohn = People({favoriteNumber: 2, name: "John"});
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// Array Variable
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People[] public people;
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function addNewPerson2(
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string memory _name,
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uint256 _favoriteNumber
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) public {
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//People memory newPerson = People(_favoriteNumber, _name);
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people.push(People(_favoriteNumber, _name));
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nameToFavoriteNumber[_name] = _favoriteNumber;
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}
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/*
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calldata - tmp data cannot modify
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memory - tmp dta can modify
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storage - permanent data can modify
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*/
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// Mapping - Easy to find data (Like Java HashMap)
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mapping(string => uint256) public nameToFavoriteNumber;
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/*
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EVM, Ethereum Virtual Machine
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Avalanche, Fantom, Polygon
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*/
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}
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