Amity Online - Solidity summary session

Hello.sol

pragma solidity >=0.5.0<= 0.7.0;


contract Hello {
    
    string public owner; 
    
    constructor(string memory _owner) public {
        
        owner = _owner;
    }
    
    function greetUser(string memory name) public pure returns(string memory) {
        
        return string(abi.encodePacked("Greetings,  ", name));
        
    }
   
}

TodoList.sol

pragma solidity >=0.5.0<= 0.7.0;


contract TodoList {
    
    string public owner; 
    
    uint public taskCounter = 0;
    
    struct Task {
        uint index;
        string content;
        bool completed;
        uint timestamp;
    }
    
    mapping(uint=>Task) public tasks;

    
    constructor(string memory _owner) public {
        
        owner = _owner;
    }
    
    
    function createTask(string memory _content) public {
        
        taskCounter ++;
        Task memory task = Task(taskCounter, _content, false, block.timestamp);
        
        tasks[taskCounter] = task;
    
    }
    
    function toggleTask(uint _index) public {
        
        tasks[_index].completed = ! tasks[_index].completed;
        
    }
    
}