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I have this smart contract from Hash Lip's github that, from what I can tell should be minting 1 at a time, but is instead minting 2 every time. Code as follows:

Setup code:

// SPDX-License-Identifier: GPL-3.0

// Created by HashLips
// The Nerdy Coder Clones

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

contract TestBoxes is ERC721Enumerable, Ownable {
  using Strings for uint256;

  string public baseURI;
  string public baseExtension = ".json";
  uint256 public cost = 0.01 ether;
  uint256 public maxSupply = 3;  //there should only be 3 minted (I have 3 image files to test)
  uint256 public maxMintAmount = 3;
  bool public paused = false;
  mapping(address => bool) public whitelisted;

And then the part where the contract is minting is as follows. as you can see above, I have set the max as 3, and in the next part, after the constructor executes, it mints 1 NFT for the owner.


  constructor(
    string memory _name,
    string memory _symbol,
    string memory _initBaseURI
  ) ERC721(_name, _symbol) {
    setBaseURI(_initBaseURI);
    mint(msg.sender, 1); //should mint 1 at deployment but mints 2...
  }

  // internal
  function _baseURI() internal view virtual override returns (string memory) {
    return baseURI;
  }

  // public
  function mint(address _to, uint256 _mintAmount) public payable {
    uint256 supply = totalSupply();
    require(!paused);
    require(_mintAmount > 0);
    require(_mintAmount <= maxMintAmount);
    require(supply + _mintAmount <= maxSupply);

    if (msg.sender != owner()) {
        if(whitelisted[msg.sender] != true) {
          require(msg.value >= cost * _mintAmount);
        }
    }

    for (uint256 i = 0; i <= _mintAmount; i++) { //start the index at 0
      _safeMint(_to, supply + i);
    }
  }
Meowsleydale
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  • I don't want to say anything bad about hashlips but you should probably find a different source for your smart contract code. – pguardiario Oct 07 '21 at 08:26

2 Answers2

3

You have a logical error in the for loop within the mint() function.

for (uint256 i = 0; i <= _mintAmount; i++)

Example: _mintAmount is 1 (same as passing from the constructor).

  • First iteration:

    i is 0, which is less or equal 1

    => performs the iteration and executes the _safeMint()

  • Second iteration:

    i is 1, which is less or equal 1

    => it still performs the iteration and executes the _safeMint()

Fix it by changing the condition to i < _mintAmoun (i is less than). Then it will only execute once (for mintAmount value 1).

Petr Hejda
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0
for (uint256 i = 1; i <= _mintAmount; i++)

The way above works the same way.

AFONSO DALVI
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