如何估算呼叫智能合約方法的成本？

在乙太坊測試網上成功部署此智能合約後

https://testnet.etherscan.io/address/0x27c042342C9ba937214117e11A4970A6145034cB

是否可以計算呼叫智能合約的給定方法需要多少氣體？

閱讀如何在沒有任何輸入參數的情況下估計函式的氣體？以及使用契約的費用是多少？估計Gas的限制是什麼？它的估計什麼時候會嚴重錯誤？沒有像預期的那樣幫助我…

這是在 geth 控制台命令行上實例化智能合約的方法：

// creation of contract object
var aContract = web3.eth.contract([ { "constant": true, "inputs": [], "name": "queryNumEscrows", "outputs": [ { "name": "", "type": "uint256", "value": "0" } ], "type": "function" }, { "constant": true, "inputs": [ { "name": "escrowId", "type": "uint256" } ], "name": "queryStatus", "outputs": [ { "name": "status", "type": "uint256", "value": "0" } ], "type": "function" }, { "constant": false, "inputs": [ { "name": "seller", "type": "address" }, { "name": "thirdParty", "type": "address" } ], "name": "start1", "outputs": [ { "name": "escrowId", "type": "uint256" } ], "type": "function" }, { "constant": false, "inputs": [ { "name": "escrowId", "type": "uint256" } ], "name": "revoke", "outputs": [ { "name": "amount", "type": "uint256" } ], "type": "function" }, { "constant": false, "inputs": [ { "name": "escrowId", "type": "uint256" } ], "name": "release", "outputs": [ { "name": "amount", "type": "uint256" } ], "type": "function" }, { "constant": false, "inputs": [ { "name": "seller", "type": "address" }, { "name": "thirdParty", "type": "address" } ], "name": "start", "outputs": [ { "name": "", "type": "uint256" } ], "type": "function" }, { "constant": false, "inputs": [], "name": "kill", "outputs": [], "type": "function" } ]);

// initiate contract for an address
var sc = aContract.at('0x27c042342C9ba937214117e11A4970A6145034cB');

// view code
eth.getCode(sc.address);

現在，我想將此交易發送到智能合約，但我想知道它需要多少 gas：

sc.start.sendTransaction("0x90e8682b63d7922a3e942d4bbd4c88095634a17b", "0x47978a69f410d0f61850c92acdb0d4c464d70937", {from:"0x3b877e80b5c0b29d88f3768ed4292b35fdd93a9d", value:"0x3b9aca00"});

為避免此消息：

"Warning! Error encountered during contract execution [Out of gas]".

我想應該使用以下 json-rpc 方法：

https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_estimategas

我在文件中讀到：

When calling SCs => data: DATA - (optional) Hash of the method signature and encoded parameters.

但是不知道如何在數據欄位中編碼方法名稱、參數和 ABI。任何的想法？

或者有沒有其他方法可以解決這個問題？

謝謝。

文件在細節上很簡陋，我花了很長時間才在您的連結的幫助下找出正確的方法，無論如何，這對我有用：

在 Geth 上測試：1.6.7 -stable、web3.js：0.20.2 Parity/v1.7.2 和 Kovan 測試網。

我將使用最小令牌作為範例：

pragma solidity ^0.4.0;

contract minimalToken {

    mapping (address => uint256) public balanceOf;

   function minimalToken(uint256 initialSupply) {
       balanceOf[msg.sender] = initialSupply;
   }

   function transfer(address _to, uint256 _value) {
       require(balanceOf[msg.sender] >= _value);
       require(balanceOf[_to] + _value >= balanceOf[_to]);
       balanceOf[msg.sender] -= _value;
       balanceOf[_to] += _value;
   }
}

我將重點介紹使用 2 個參數（地址、金額）進行傳輸的傳輸方法：

   var contract = web3.eth.contract(contractABI).at("0x8caaa1f263ff14d0276ff1a1a6ed15c51159d6e0");
   var receiverAddress = '0x00Ce6C92856A657979E7728005DBc9acD002Eb09';
   var callData = contract.transfer.getData(receiverAddress, 2000);

   var gasEstimate = web3.eth.estimateGas({
       from: web3.eth.coinbase,
       to: "0x8caaa1f263ff14d0276ff1a1a6ed15c51159d6e0",
       data: callData
   });

   var gasPrice = web3.eth.gasPrice;

   console.log('gas Price: ' + gasPrice);
   console.log('Estimated Transaction gas: ' + gasEstimate);

// gas Price: 21000000000
// Estimated Transaction gas: 34207

讓我失望的一件事是，由於我不包括交易中的**from:**欄位，我不斷收到交易錯誤。

希望這可以幫助。

引用自：https://ethereum.stackexchange.com/questions/9249