একটি সলিডিটি স্মার্ট কন্ট্রাক্ট থেকে ERC-20 টোকেনের ট্রান্সফার এবং অ্যাপ্রুভাল

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
14    event Transfer(address indexed from, address indexed to, uint256 value);
15    event Approval(address indexed owner, address indexed spender, uint256 value);
16}
17
18
19contract ERC20Basic is IERC20 {
20
21    string public constant name = "ERC20Basic";
22    string public constant symbol = "ERC";
23    uint8 public constant decimals = 18;
24
25
26    mapping(address => uint256) balances;
27
28    mapping(address => mapping (address => uint256)) allowed;
29
30    uint256 totalSupply_ = 10 ether;
31
32
33   constructor() {
34	balances[msg.sender] = totalSupply_;
35    }
36
37    function totalSupply() public override view returns (uint256) {
38	return totalSupply_;
39    }
40
41    function balanceOf(address tokenOwner) public override view returns (uint256) {
42        return balances[tokenOwner];
43    }
44
45    function transfer(address receiver, uint256 numTokens) public override returns (bool) {
46        require(numTokens <= balances[msg.sender]);
47        balances[msg.sender] = balances[msg.sender]-numTokens;
48        balances[receiver] = balances[receiver]+numTokens;
49        emit Transfer(msg.sender, receiver, numTokens);
50        return true;
51    }
52
53    function approve(address delegate, uint256 numTokens) public override returns (bool) {
54        allowed[msg.sender][delegate] = numTokens;
55        emit Approval(msg.sender, delegate, numTokens);
56        return true;
57    }
58
59    function allowance(address owner, address delegate) public override view returns (uint) {
60        return allowed[owner][delegate];
61    }
62
63    function transferFrom(address owner, address buyer, uint256 numTokens) public override returns (bool) {
64        require(numTokens <= balances[owner]);
65        require(numTokens <= allowed[owner][msg.sender]);
66
67        balances[owner] = balances[owner]-numTokens;
68        allowed[owner][msg.sender] = allowed[owner][msg.sender]-numTokens;
69        balances[buyer] = balances[buyer]+numTokens;
70        emit Transfer(owner, buyer, numTokens);
71        return true;
72    }
73}
74
75
সব দেখানকপি করুন

1contract DEX {
2
3    IERC20 public token;
4
5    event Bought(uint256 amount);
6    event Sold(uint256 amount);
7
8    constructor() {
9        token = new ERC20Basic();
10    }
11
12    function buy() payable public {
13        // TODO
14    }
15
16    function sell(uint256 amount) public {
17        // TODO
18    }
19
20}
সব দেখানকপি করুন

1function buy() payable public {
2    uint256 amountTobuy = msg.value;
3    uint256 dexBalance = token.balanceOf(address(this));
4    require(amountTobuy > 0, "You need to send some ether");
5    require(amountTobuy <= dexBalance, "Not enough tokens in the reserve");
6    token.transfer(msg.sender, amountTobuy);
7    emit Bought(amountTobuy);
8}
কপি করুন

1# ### ইন্টারেক্টিভ ব্রাউনি কনসোলে পাইথন...
2
3# DEX ডিপ্লয় করুন
4dex = DEX.deploy({'from':account1})
5
6# টোকেনের জন্য ইথার সোয়াপ করতে buy ফাংশনটি কল করুন
7# 1e18 হলো ওয়েই (wei) এককে ১ ইথার
8dex.buy({'from': account2, 1e18})
9
10# ERC20 টোকেনের ডিপ্লয়মেন্ট অ্যাড্রেসটি সংগ্রহ করুন
11# যা DEX কন্ট্রাক্ট তৈরির সময় ডিপ্লয় করা হয়েছিল
12# dex.token() টোকেনের ডিপ্লয় করা অ্যাড্রেসটি রিটার্ন করে
13token = ERC20Basic.at(dex.token())
14
15# টোকেনের approve ফাংশনটি কল করুন
16# স্পেন্ডার হিসেবে dex অ্যাড্রেসটিকে অ্যাপ্রুভ করুন
17# এবং এটি আপনার কতগুলো টোকেন খরচ করার অনুমতি পাবে
18token.approve(dex.address, 3e18, {'from':account2})
19
সব দেখানকপি করুন

1function sell(uint256 amount) public {
2    require(amount > 0, "You need to sell at least some tokens");
3    uint256 allowance = token.allowance(msg.sender, address(this));
4    require(allowance >= amount, "Check the token allowance");
5    token.transferFrom(msg.sender, address(this), amount);
6    payable(msg.sender).transfer(amount);
7    emit Sold(amount);
8}
কপি করুন

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
14    event Transfer(address indexed from, address indexed to, uint256 value);
15    event Approval(address indexed owner, address indexed spender, uint256 value);
16}
17
18
19contract ERC20Basic is IERC20 {
20
21    string public constant name = "ERC20Basic";
22    string public constant symbol = "ERC";
23    uint8 public constant decimals = 18;
24
25
26    mapping(address => uint256) balances;
27
28    mapping(address => mapping (address => uint256)) allowed;
29
30    uint256 totalSupply_ = 10 ether;
31
32
33   constructor() {
34	balances[msg.sender] = totalSupply_;
35    }
36
37    function totalSupply() public override view returns (uint256) {
38	return totalSupply_;
39    }
40
41    function balanceOf(address tokenOwner) public override view returns (uint256) {
42        return balances[tokenOwner];
43    }
44
45    function transfer(address receiver, uint256 numTokens) public override returns (bool) {
46        require(numTokens <= balances[msg.sender]);
47        balances[msg.sender] = balances[msg.sender]-numTokens;
48        balances[receiver] = balances[receiver]+numTokens;
49        emit Transfer(msg.sender, receiver, numTokens);
50        return true;
51    }
52
53    function approve(address delegate, uint256 numTokens) public override returns (bool) {
54        allowed[msg.sender][delegate] = numTokens;
55        emit Approval(msg.sender, delegate, numTokens);
56        return true;
57    }
58
59    function allowance(address owner, address delegate) public override view returns (uint) {
60        return allowed[owner][delegate];
61    }
62
63    function transferFrom(address owner, address buyer, uint256 numTokens) public override returns (bool) {
64        require(numTokens <= balances[owner]);
65        require(numTokens <= allowed[owner][msg.sender]);
66
67        balances[owner] = balances[owner]-numTokens;
68        allowed[owner][msg.sender] = allowed[owner][msg.sender]-numTokens;
69        balances[buyer] = balances[buyer]+numTokens;
70        emit Transfer(owner, buyer, numTokens);
71        return true;
72    }
73}
74
75
76contract DEX {
77
78    event Bought(uint256 amount);
79    event Sold(uint256 amount);
80
81
82    IERC20 public token;
83
84    constructor() {
85        token = new ERC20Basic();
86    }
87
88    function buy() payable public {
89        uint256 amountTobuy = msg.value;
90        uint256 dexBalance = token.balanceOf(address(this));
91        require(amountTobuy > 0, "You need to send some ether");
92        require(amountTobuy <= dexBalance, "Not enough tokens in the reserve");
93        token.transfer(msg.sender, amountTobuy);
94        emit Bought(amountTobuy);
95    }
96
97    function sell(uint256 amount) public {
98        require(amount > 0, "You need to sell at least some tokens");
99        uint256 allowance = token.allowance(msg.sender, address(this));
100        require(allowance >= amount, "Check the token allowance");
101        token.transferFrom(msg.sender, address(this), amount);
102        payable(msg.sender).transfer(amount);
103        emit Sold(amount);
104    }
105
106}
সব দেখানকপি করুন