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Solidity Hello World Voting DApp
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pragma solidity ^0.4.18; | |
// 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 => uint8) 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 | |
*/ | |
function Voting(bytes32[] candidateNames) public { | |
candidateList = candidateNames; | |
} | |
// This function returns the total votes a candidate has received so far | |
function totalVotesFor(bytes32 candidate) view public returns (uint8) { | |
require(validCandidate(candidate)); | |
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 { | |
require(validCandidate(candidate)); | |
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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