pragma solidity ^0.6.0;

contract UserCrud{
    struct userStruct{
        uint userAge;
        uint index;
        bytes32 userName;
        bytes32 userEmail;
    mapping(address => userStruct) private userStructs;
    address[] private userIndex;

    function insertUser(
    address userAddress,
    uint userAge,
    bytes32 userName,
    bytes32 userEmail) public returns (uint index) {
        userStructs[userAddress].userAge = userAge;
        userStructs[userAddress].userName = userName;
        userStructs[userAddress].userEmail = userEmail;
        userStructs[userAddress].index = userIndex.push(userAddress) - 1; //error in this line

I got this code from an article regarding Solidity CRUD and was doing some modifications, but I'm facing an error as follows:

TypeError: Type tuple() is not implicitly convertible to expected type uint256. userStructs[userAddress].index = userIndex.push(userAddress) - 1;

1 Answer 1


The problems is that since solc v0.6.0 userIndex.push(userAddress) no longer return the length as in previous versions.

You can fix the code with something like this

userStructs[userAddress].index = userIndex.length - 1;
  • It removed the error but gave a Warning: Unused function parameter. Remove or comment out the variable name to silence this warning. bytes32 userEmail) public returns (uint index) { which I can't remove. Sorry I'm new in solidity :(
    – Raman
    Commented Oct 10, 2021 at 7:29
  • @Raman In this question ethereum.stackexchange.com/questions/72486/… you'll find a solution. In most cases it is faster to search the error message.
    – Ismael
    Commented Oct 10, 2021 at 15:49

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