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ballot.sol

pragma solidity 0.4.25;
/*数组类型Demo*/
contract DemoTypes303 {
  /*String数组例子*/
  string[] strArr;
  function add(string str) public {
    strArr.push(str);
  }
  function getStrAt(uint n)  public constant returns (string s){
    string storage tmp = strArr[n];
    return tmp;
  }

  function updateStrAt(uint n, string str)  public {
    strArr[n] = str;
  }

  function deleteStrAt(uint index)  public  {
    uint len = strArr.length;
    if (index >= len) return;
    for (uint i = index; i<len-1; i++) {
      strArr[i] = strArr[i+1];
    }

    delete strArr[len-1];
    strArr.length--;
  }
}

call_delegate.sol

pragma solidity ^0.4.25;
contract CA{
    uint public p;
    event e(address add,uint p);
    function fun(uint u1,uint u2)public{
        p = u1 + u2;
        emit e(msg.sender,p);
    }
}
contract CB{
    uint public q;
    bool public b;
    
    function CB() public payable {
        
    }
    
    function call1(address add)public returns(bool) {
        b = add.call(bytes4(keccak256("fun(uint256,uint256)")),2,3);
        return b;
    }
    
    function call2(address add)public returns(bool){
        b = add.delegatecall(bytes4(keccak256("fun(uint256,uint256)")),1,2);
        return b;
    }
    
    function sendDemo(address add) public{
        uint u = 1 ether;
        add.transfer(u);
    }
}

eventFilterTest.sol

pragma solidity ^0.4.25;
contract EventFilterTest {
    constructor() public {
        b = 0x12345678901234567890123456789012;
    }
    event Event(uint indexed a, bytes32 b) ;
     event Event2(uint indexed a, bytes32 b) ;

   function foo(uint a) public {
       b =  bytes32(1);
        emit Event(a, b);
        emit Event2(a, b);
    }
    bytes32 b;
}

EventTest.sol

pragma solidity ^0.4.25;
contract SimpleStorage {
    uint public data;
    // event SetX(address indexed _from, uint value);
    event Set(string label, uint value);
    function set(uint x) public {
        data = x;
        // emit SetX(msg.sender, x);
        // emit Set("#####", x);
    }
}

mem_vs_storage.sol

pragma solidity 0.4.25;

contract C {
    uint[] data1;
    uint[] data2;

    function appendOne() public {
        append(data1);
    }

    function appendTwo() public {
        append(data2);
    }

    function append(uint[] storage d) internal {
        d.push(1);
    }
    function getData1() view public returns(uint[]){
        return data1;
    }
    function getData2() view public returns(uint[]){
        return data2;
    }
}

contract C2 {
    uint public someVariable ;
    uint[] public data;

    function f() public {
        uint[] x;
        x.push(2);
        data = x;
    }
}

contract ConstantTest{

uint constant var1=now;
uint var2=now;

function checkConstant() returns(uint,uint){
    return (var1,var2);
}
    function getVar1() returns(uint){ return var1;}
    function getVar2() returns(uint){ return var2;}
} 

sc_balance.sol

pragma solidity 0.4.25;
contract InfoFeed {
    address owner;
    
    constructor(){
        owner = msg.sender;
    }
		    function info() returns (uint ret) { return 42; }
		    function getBalance() public returns (uint) { 
		        return this.balance; 
		    }
		    
		     function kill() public {
               if (owner == msg.sender) { // 检查谁在调用
                  selfdestruct(owner); // 销毁合约
               }
    }
}
		
contract Consumer {
		    InfoFeed public feed; // points to contract on blockchain
		
		    constructor() {
		         // 会触发构造函数！
		        feed = new InfoFeed(); // new instance created; constructor called
		    }
		    function getBalance() public returns (uint) { 
		        return this.balance; 
		    }
		    
		    function doTransfer(uint val) {
		        address(this).transfer(10);
		    }
}
		

sc_send_eth.sol

pragma solidity ^0.4.25;
contract EthToContract {
 
 uint256 public counter = 5; //state variable we assigned earlier
 address public owner = msg.sender; //set owner as msg.sender
 
function add() public {  //increases counter by 1
  counter++;
 }
 
 function subtract() public { //decreases counter by 1
  counter--;
 }
 function getCounter() public constant returns (uint256) {
  return counter;
    } 
 function kill() public { //self-destruct function, 
   if(msg.sender == owner) {
    selfdestruct(owner); 
        }
    }
}