ERC20 Token agreement

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ERC20 The development process of tokens can be divided into two steps

1. Definition ERC20 Token standard interface
2. Token protocol inherits standard interface

ERC20 Standard interface

pragma solidity ^0.4.20;
 
//  Definition ERC-20 Standard interface 
 
contract ERC20Interface {
 
    //  Token name 
 
    string public name;
 
    //  Token symbol or abbreviation 
 
    string public symbol;
 
    //  Token decimal places , The smallest unit of token 
 
    uint8 public decimals;
 
    //  The total amount of tokens issued 
 
    uint public totalSupply;
 
 
 
    //  Realize token transaction , Used to transfer tokens to an address 
 
    function transfer(address to, uint tokens) public returns (bool success);
 
    //  Realize transactions between token users , Transfer tokens from one address to another 
 
    function transferFrom(address from, address to, uint tokens) public returns (bool success);
 
    //  allow spender Withdraw money from your account many times , And at most tokens individual , It is mainly used in some scenarios to authorize other users to spend tokens from your account 
 
    function approve(address spender, uint tokens) public returns (bool success);
 
    //  Inquire about spender Allow from tokenOwner The number of tokens spent on 
 
    function allowance(address tokenOwner, address spender) public view returns (uint remaining);
 
 
 
    //  Event triggered during token transaction , That is to call transfer Method 
 
    event Transfer(address indexed from, address indexed to, uint tokens);
 
    //  Events triggered when allowing other users to spend tokens from your account , That is to call approve Method 
 
    event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
 
}

Inherit ERC20 Interface

//  Realization ERC-20 Standard interface 
 
contract ERC20Impl is ERC20Interface {
 
    //  Store the balance of each address （ the reason being that public So it will be generated automatically balanceOf Method ）
 
    mapping (address => uint256) public balanceOf;
 
    //  Store the operable address of each address and its operable amount 
 
    mapping (address => mapping (address => uint256)) internal allowed;
 
 
 
    //  Initialization property 
 
    constructor() public {
 
        name = "TestByteGoToken";             //  Definition   Token name 
 
        symbol = "TBG22";                           //  Abbreviation of token 
 
        decimals = 18;
 
        totalSupply = 100000000 * 10 ** uint256(decimals);       //  The total amount of tokens 
 
        //  The account that initializes the token will have all the tokens 
 
        balanceOf[msg.sender] = totalSupply;                    //  When initializing , Who does this token belong to 
 
    }
 
 
 
    function transfer(address to, uint tokens) public returns (bool success) {
 
        //  Check whether the recipient address is legal 
 
        require(to != address(0));
 
        //  Check whether the sender's account balance is sufficient 
 
        require(balanceOf[msg.sender] >= tokens);
 
        //  Check whether overflow will occur 
 
        require(balanceOf[to] + tokens >= balanceOf[to]);
 
 
 
        //  Deduct the sender's account balance 
 
        balanceOf[msg.sender] -= tokens;
 
        //  Increase the recipient's account balance 
 
        balanceOf[to] += tokens;
 
 
 
        //  Trigger the corresponding event 
 
        emit Transfer(msg.sender, to, tokens);
 
    }
 
 
 
    function transferFrom(address from, address to, uint tokens) public returns (bool success) {
 
        //  Check whether the address is legal 
 
        require(to != address(0) && from != address(0));
 
        //  Check whether the sender's account balance is sufficient 
 
        require(balanceOf[from] >= tokens);
 
        //  Check whether the amount of operation is allowed 
 
        require(allowed[from][msg.sender] <= tokens);
 
        //  Check whether overflow will occur 
 
        require(balanceOf[to] + tokens >= balanceOf[to]);
 
 
 
        //  Deduct the sender's account balance 
 
        balanceOf[from] -= tokens;
 
        //  Increase the recipient's account balance 
 
        balanceOf[to] += tokens;
 
 
 
        //  Trigger the corresponding event 
 
        emit Transfer(from, to, tokens);  
 
 
 
        success = true;
 
    }
 
 
 
    function approve(address spender, uint tokens) public returns (bool success) {
 
        allowed[msg.sender][spender] = tokens;
 
        //  Trigger the corresponding event 
 
        emit Approval(msg.sender, spender, tokens);
 
 
 
        success = true;
 
    }
 
 
 
    function allowance(address tokenOwner, address spender) public view returns (uint remaining) {
 
        return allowed[tokenOwner][spender];
 
    }
 
}

The last look

pragma solidity ^0.4.20;
 
//  Definition ERC-20 Standard interface 
 
contract ERC20Interface {
 
    //  Token name 
 
    string public name;
 
    //  Token symbol or abbreviation 
 
    string public symbol;
 
    //  Token decimal places , The smallest unit of token 
 
    uint8 public decimals;
 
    //  The total amount of tokens issued 
 
    uint public totalSupply;
 
 
 
    //  Realize token transaction , Used to transfer tokens to an address 
 
    function transfer(address to, uint tokens) public returns (bool success);
 
    //  Realize transactions between token users , Transfer tokens from one address to another 
 
    function transferFrom(address from, address to, uint tokens) public returns (bool success);
 
    //  allow spender Withdraw money from your account many times , And at most tokens individual , It is mainly used in some scenarios to authorize other users to spend tokens from your account 
 
    function approve(address spender, uint tokens) public returns (bool success);
 
    //  Inquire about spender Allow from tokenOwner The number of tokens spent on 
 
    function allowance(address tokenOwner, address spender) public view returns (uint remaining);
 
 
 
    //  Event triggered during token transaction , That is to call transfer Method 
 
    event Transfer(address indexed from, address indexed to, uint tokens);
 
    //  Events triggered when allowing other users to spend tokens from your account , That is to call approve Method 
 
    event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
 
}
 
 
 
//  Realization ERC-20 Standard interface 
 
contract ERC20Impl is ERC20Interface {
 
    //  Store the balance of each address （ the reason being that public So it will be generated automatically balanceOf Method ）
 
    mapping (address => uint256) public balanceOf;
 
    //  Store the operable address of each address and its operable amount 
 
    mapping (address => mapping (address => uint256)) internal allowed;
 
 
 
    //  Initialization property 
 
    constructor() public {
 
        name = "TestByteGoToken";             //  Definition   Token name 
 
        symbol = "TBG22";                           //  Abbreviation of token 
 
        decimals = 18;
 
        totalSupply = 100000000 * 10 ** uint256(decimals);       //  The total amount of tokens 
 
        //  The account that initializes the token will have all the tokens 
 
        balanceOf[msg.sender] = totalSupply;                    //  When initializing , Who does this token belong to 
 
    }
 
 
 
    function transfer(address to, uint tokens) public returns (bool success) {
 
        //  Check whether the recipient address is legal 
 
        require(to != address(0));
 
        //  Check whether the sender's account balance is sufficient 
 
        require(balanceOf[msg.sender] >= tokens);
 
        //  Check whether overflow will occur 
 
        require(balanceOf[to] + tokens >= balanceOf[to]);
 
 
 
        //  Deduct the sender's account balance 
 
        balanceOf[msg.sender] -= tokens;
 
        //  Increase the recipient's account balance 
 
        balanceOf[to] += tokens;
 
 
 
        //  Trigger the corresponding event 
 
        emit Transfer(msg.sender, to, tokens);
 
    }
 
 
 
    function transferFrom(address from, address to, uint tokens) public returns (bool success) {
 
        //  Check whether the address is legal 
 
        require(to != address(0) && from != address(0));
 
        //  Check whether the sender's account balance is sufficient 
 
        require(balanceOf[from] >= tokens);
 
        //  Check whether the amount of operation is allowed 
 
        require(allowed[from][msg.sender] <= tokens);
 
        //  Check whether overflow will occur 
 
        require(balanceOf[to] + tokens >= balanceOf[to]);
 
 
 
        //  Deduct the sender's account balance 
 
        balanceOf[from] -= tokens;
 
        //  Increase the recipient's account balance 
 
        balanceOf[to] += tokens;
 
 
 
        //  Trigger the corresponding event 
 
        emit Transfer(from, to, tokens);  
 
 
 
        success = true;
 
    }
 
 
 
    function approve(address spender, uint tokens) public returns (bool success) {
 
        allowed[msg.sender][spender] = tokens;
 
        //  Trigger the corresponding event 
 
        emit Approval(msg.sender, spender, tokens);
 
 
 
        success = true;
 
    }
 
 
 
    function allowance(address tokenOwner, address spender) public view returns (uint remaining) {
 
        return allowed[tokenOwner][spender];
 
    }
 
}

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