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pragma solidity ^0.5.0;

contract A {
    uint public a;
    
    //A constructor set asinternalcauses the contract to be marked asabstract
    constructor(uint _a) internal {
        a = _a;
    }
}

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pragma solidity ^0.5.0;

contract Sharer {
    function sendHalf(address payable addr) public payable returns (uint balance){
        require(msg.value % 2 == 0, "Even value reqired.");
        uint balanceBeforeTransfer = address(this).balance;
        addr.transfer(msg.value / 2);
        // Since transfer throws an exception on failure and
        // cannot call back here, there should be no way for us to
        // still have half of the money.

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pragma solidity >0.4.23 <0.6.0;

contract C {
    uint[] data;
    
    function f() public pure returns(uint, bool, uint){
        return (7, true, 2);
    }
    
    function g() public {

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pragma solidity >=0.4.0 <0.6.0;
contract UnitExample {
    
    function test() public {
        assert(1 wei == 1);
        assert(1 szabo == 1e12);
        assert(1 finney == 1e15);
        assert(1 ether == 1e18);
        
        //The suffix years has been removed in version 0.5.0 due to::

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pragma solidity >=0.4.0 <0.6.0;
contract ConversionExample {
    
    function test() public {
        int8 y = -3;
        uint x =uint(y); //0xfffff..fd
        
        uint32 a = 0x12345678;
        uint16 b = uint16(a);// b will be 0x5678 now
        

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pragma solidity >=0.4.0 <0.6.0;
contract DeleteExample {
    uint data;
    uint[] dataArray;
    
    function f() public {
        uint x = data;
        delete x; //sets x to 0, does not affect data
        delete data; // sets data to 0, does not affect x
        uint[] storage y = dataArray;

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pragma solidity >=0.4.0 <0.6.0;
/// @dev Models a uint -> uint mapping where it is possible to iterate over all keys.
library IterableMapping
{
  struct itmap
  {
    mapping(uint => IndexValue) data;
    KeyFlag[] keys;
    uint size;
  }

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pragma solidity >=0.4.11 <0.6.0;
contract CrowFunding {
    // Defines a new type with two fields
    struct Funder {
        address addr;
        uint amount;
    }
    struct Campaign {
        address payable beneficiary;
        uint fundingGoal;

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pragma solidity >=0.4.0 <0.6.0;
contract C {
    uint[] x;
    // the data location of x is storage
    // the data location of memoryArray is memory
    function f(uint[] memory memoryArray) public{
        x = memoryArray; // works, copies the whole array to storage
        uint[] storage y = x; // works, assigns a pointer, data location of y is storage
        //y[7]; // fine, returns the 8th element
        //y.length = 2;   // fine, modifies x through y

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pragma solidity >=0.4.16 <0.6.0;

contract Oracle{
    struct Request{
        bytes data;
        function(uint) external callback;
    }
    Request[] requests;
    event NewRequest(uint);
    event Reply(uint);