فهم العقد الذكي لرمز ERC-20

1pragma solidity ^0.6.0;
2
3interface IERC20 {
4
5    function totalSupply() external view returns (uint256);
6    function balanceOf(address account) external view returns (uint256);
7    function allowance(address owner, address spender) external view returns (uint256);
8
9    function transfer(address recipient, uint256 amount) external returns (bool);
10    function approve(address spender, uint256 amount) external returns (bool);
11    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
12
13    event Transfer(address indexed from, address indexed to, uint256 value);
14    event Approval(address indexed owner, address indexed spender, uint256 value);
15}
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1function totalSupply() external view returns (uint256);
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1function balanceOf(address account) external view returns (uint256);
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1function allowance(address owner, address spender) external view returns (uint256);
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1function transfer(address recipient, uint256 amount) external returns (bool);
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1function approve(address spender, uint256 amount) external returns (bool);
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1function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
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1event Transfer(address indexed from, address indexed to, uint256 value);
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1event Approval(address indexed owner, address indexed spender, uint256 value);
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1pragma solidity ^0.8.0;
2
3interface IERC20 {
4
5    function totalSupply() external view returns (uint256);
6    function balanceOf(address account) external view returns (uint256);
7    function allowance(address owner, address spender) external view returns (uint256);
8
9    function transfer(address recipient, uint256 amount) external returns (bool);
10    function approve(address spender, uint256 amount) external returns (bool);
11    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
12
13    event Transfer(address indexed from, address indexed to, uint256 value);
14    event Approval(address indexed owner, address indexed spender, uint256 value);
15}
16
17contract ERC20Basic is IERC20 {
18
19    string public constant name = "ERC20Basic";
20    string public constant symbol = "ERC";
21    uint8 public constant decimals = 18;
22
23    mapping(address => uint256) balances;
24
25    mapping(address => mapping (address => uint256)) allowed;
26
27    uint256 totalSupply_ = 10 ether;
28
29   constructor() {
30	balances[msg.sender] = totalSupply_;
31    }
32
33    function totalSupply() public override view returns (uint256) {
34	return totalSupply_;
35    }
36
37    function balanceOf(address tokenOwner) public override view returns (uint256) {
38        return balances[tokenOwner];
39    }
40
41    function transfer(address receiver, uint256 numTokens) public override returns (bool) {
42        require(numTokens <= balances[msg.sender]);
43        balances[msg.sender] = balances[msg.sender]-numTokens;
44        balances[receiver] = balances[receiver]+numTokens;
45        emit Transfer(msg.sender, receiver, numTokens);
46        return true;
47    }
48
49    function approve(address delegate, uint256 numTokens) public override returns (bool) {
50        allowed[msg.sender][delegate] = numTokens;
51        emit Approval(msg.sender, delegate, numTokens);
52        return true;
53    }
54
55    function allowance(address owner, address delegate) public override view returns (uint) {
56        return allowed[owner][delegate];
57    }
58
59    function transferFrom(address owner, address buyer, uint256 numTokens) public override returns (bool) {
60        require(numTokens <= balances[owner]);
61        require(numTokens <= allowed[owner][msg.sender]);
62
63        balances[owner] = balances[owner]-numTokens;
64        allowed[owner][msg.sender] = allowed[owner][msg.sender]-numTokens;
65        balances[buyer] = balances[buyer]+numTokens;
66        emit Transfer(owner, buyer, numTokens);
67        return true;
68    }
69}
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