QZdY6rvk

1pragma solidity ^0.4.18;
2
3    /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
4    File Name: voting.sol
5    Author: Rakesh Kumar Kanduri
6    Date: 05-Jul-2019
7    Note: Written for Solidity version 0.4.18 and above that doesn't break functionality
8    * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
9    
10contract Voting {
11    // an event that is called whenever a Candidate is added so the frontend could
12    // appropriately display the candidate with the right element id (it is used
13    // to vote for the candidate, since it is one of arguments for the function
14    //"vote")
15    event AddedCandidate(uint candidateID);
16    
17    // describes a Voter, which has an id and the ID of the candidate they voted for
18    address owner;
19    
20    function Voting() public {
21        owner=msg.sender; 
22    }
23    
24    modifier onlyOwner {
25        // describes a Candidate
26        require(msg.sender == owner);
27        _;
28    }
29    
30    struct Voter {
31        uint candidateIDVote; // this flag will help authorization of voter
32        bool isAuthorized;
33        bool hasVoted;  // this flag will help to keep track of 1 voter - 1 vote
34    }
35
36    // describes a Candidate
37    struct Candidate {
38        string name;
39        string party;
40        uint noOFVotes;
41        bool doesExist; // "bool doesExist" is to check if this Struct exists
42    }
43    
44    // This is so that we can keep track of the candidates
45    // These state variables are used keep track of the number of Candidates/Voters and used to as a way to index them
46    
47    uint numCandidates; // declares a state variable - number Of Candidates
48    uint numVoters; // declares a state variable - number Of Voters
49    uint numOfVotes; // declares a state variable - number Of Votes
50    
51    // Think of these as a hash table, with the key as a uint and value of
52    // the struct Candidate/Voter. These mappings will be used in the majority of our transactions/calls
53    // These mappings will hold all the candidates and Voters respectively
54    mapping (uint => Candidate) candidates;
55    mapping (address => Voter) voters;
56
57    /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
58    These functions perform transactions, editing the mappings
59    * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
60    
61    function addCandidate(string name, string party) onlyOwner public {
62        // candidateID is the return variable
63        uint candidateID = numCandidates++;
64        // Create new Candidate Struct with name and saves it to storage.
65        candidates[candidateID] = Candidate(name,party,0,true);
66        AddedCandidate(candidateID);
67    }
68    
69    function vote(uint candidateID) public {
70        // checks if the struct exists for that candidate
71        require(!voters[msg.sender].hasVoted);// this statement is to check if this voter has not voted already 
72        require(voters[msg.sender].isAuthorized);// this statement is to check if this voter is authorized to vote
73        if (candidates[candidateID].doesExist == true) {
74            voters[msg.sender] = Voter(candidateID, true, true);
75            candidates[candidateID].noOFVotes++;
76            numOfVotes++;
77            numVoters++;
78        }
79    }
80    
81    function Authorize(address _Voter) onlyOwner public {
82        voters[_Voter].isAuthorized = true;
83    }
84    
85    /* * * * * * * * * * * * * * * * * * * * * * * * * *
86    Getter Functions, marked by the key word "view"
87    * * * * * * * * * * * * * * * * * * * * * * * * * */
88    
89    // finds the total amount of votes for a specific candidate by looping
90    //through voters
91    function totalVotes(uint candidateID) view public returns (uint) {
92        return candidates[candidateID].noOFVotes;
93    }
94    
95    function getNumOfCandidates() public view returns(uint) {
96        return numCandidates;
97    }
98    
99    function getNumOfVoters() public view returns(uint) {
100        return numVoters;
101    }
102    
103    // returns candidate information, including its ID, name, and party
104    function getCandidate(uint candidateID) public view returns(uint,string,string,uint) {
105        return (candidateID,candidates[candidateID].name,candidates[candidateID].party,candidates[candidateID].noOFVotes);
106    } 
107    
108}