chapter16-code-7
Thu Mar 30 2023 11:24:09 GMT+0000 (Coordinated Universal Time)
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@RareSkills
contract ERC20 {
string public name;
string public symbol;
mapping(address => uint256) public balanceOf;
address public owner;
uint8 public decimals;
uint256 public totalSupply;
// owner -> spender -> allowance
// this enables an owner to give allowance to multiple addresses
mapping(address => mapping(address => uint256)) public allowance; // just added address public owner;
constructor(string memory _name, string memory _symbol) {
name = _name;
symbol = _symbol;
decimals = 18;
owner = msg.sender;
}
function mint(address to, uint256 amount) public {
require(msg.sender == owner, "only owner can create tokens");
totalSupply += amount;
balanceOf[owner] += amount;
}
function transfer(address to, uint256 amount) public {
require(balanceOf[msg.sender] >= amount, "you aint rich enough");
require(to != address(0), "cannot send to address(0)");
balanceOf[msg.sender] -= amount;
balanceOf[to] += amount;
}
// just added
function approve(address spender, uint256 amount) public {
allowance[msg.sender][spender] = amount;
}
}
content_copyCOPY
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