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Simple solidity contract to vote for a candidate and see the results
pragma solidity ^0.6.4;
// We have to specify what version of compiler this code will compile with
contract Voting {
/* mapping field below is equivalent to an associative array or hash.
The key of the mapping is candidate name stored as type bytes32 and value is
an unsigned integer to store the vote count
mapping (bytes32 => uint256) public votesReceived;
/* Solidity doesn't let you pass in an array of strings in the constructor (yet).
We will use an array of bytes32 instead to store the list of candidates
bytes32[] public candidateList;
/* This is the constructor which will be called once when you
deploy the contract to the blockchain. When we deploy the contract,
we will pass an array of candidates who will be contesting in the election
constructor(bytes32[] memory candidateNames) public {
candidateList = candidateNames;
// This function returns the total votes a candidate has received so far
function totalVotesFor(bytes32 candidate) view public returns (uint256) {
return votesReceived[candidate];
// This function increments the vote count for the specified candidate. This
// is equivalent to casting a vote
function voteForCandidate(bytes32 candidate) public {
votesReceived[candidate] += 1;
function validCandidate(bytes32 candidate) view public returns (bool) {
for(uint i = 0; i < candidateList.length; i++) {
if (candidateList[i] == candidate) {
return true;
return false;
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