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QRC0 Integration Technical Guide

QRC20 Integration Technical Guide
This document explains the basics of interacting with an QRC20 contract with the qtumd CLI command tool.
The full example in PHP: Qrc20.php .
Intro
We recommend that an exchange use one main address to store tokens for all users. Below MAIN_QRC_ADDRESS is the main address.
The address of the QRC20 token contract is TOKEN_CONTRACT_ADDRESS.
gas limit is DEFAULT_GAS_LIMIT, recommended value is 250000
gas price is DEFAULT_GAS_PRICE，recommended value is 0.00000040
TOKEN_DECIMALS is the decimals of the token, which varies per token. Here we set it 8.
We'll use the following utility functions:
​addressToHash160 - Convert base58 address to hash160 address.
​to32bytesArg left-pad hex data to 32 bytes with 0.
​addDecimals multiply the nominal token amount by the number of decimal places.
Running QTUMD
You should remember to enable the indexing service when starting qtumd, using the flags -logevents -txindex.
Interacting With QRC20
In the CLI examples below, please substitute {} with actual addresses and values.
Getting Token Balance
$userAddress is the deposit address
qtum-cli callcontract \
    {TOKEN_CONTRACT_ADDRESS} \
    70a08231{to32bytesArg(addressToHash160($userAddress))}
In the JSON output look for executionResult.output. This is the token balance.
Withdraw
$userAddress is the withdraw address
$amount the withdraw amount in unit token
qtum-cli sendtocontract \
    {TOKEN_CONTRACT_ADDRESS} \
    a9059cbb{to32bytesArg(addressToHash160($userAddress))}{to32bytesArg(addDecimals($amount)) \
    0 \
    {DEFAULT_GAS_LIMIT} \
    {DEFAULT_GAS_PRICE} \
    {MAIN_QRC_ADDRESS}
The command returns the txid of this transaction. You may use it to find information about this transaction (e.g. number of confirmations).
Generate a deposit address
For an exchange, a user may use the same address for both QTUM and other QRC20 tokens.
Use this command to generate a deposit address:
qtum-cli getnewaddress
Deposit and Witdraw Logs
$startingBlock is where you want to start looking (inclursive)
You can start looking from 0, but for better efficiency, you should remember where to start looking.
qtum-cli searchlogs \
    STARTING_BLOCK \
    999999999 \
    '{ "addresses": ["TOKEN_CONTRACT_ADDRESS"]}' \
    '{"topics": ["ddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"]}'
The event type filtered is the Transfer event:
event Transfer(address indexed _from, address indexed _to, uint256 _value)
Look through the logs to filter by to or from addresses.
Checking Confirmations
Given a transaction id $txid:
qtum-cli gettransaction $txid
Use the property confirmations from output.

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QRC20 Token integration

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Raw QRC20 Transaction implementation guide

Last modified 1mo ago