Problem setting uint value to zero

Question

I made a little smart contracts with solidity browser, This is my code:

pragma solidity ^0.4.0;

contract Test {
    struct User {
        string name;
        string surname;
        uint active;
    }

    mapping(bytes32 => User) public userRegister;

    function add_user(string _name, string _surname) {
        bytes32 _hc=sha3(_name, _surname);
        User p = userRegister[_hc];  

        p.name=_name;
        p.surname=_surname;
        p.active=1;
    }

    function remove(string _name, string _surname)  {
        bytes32 _hc=sha3(_name, _surname);
        userRegister[_hc].active=0;  
    }

    function active(string _name, string _surname)  {
        bytes32 _hc=sha3(_name, _surname);
        userRegister[_hc].active=1;  
    }
}

When I use "JavaScript VM" everything's fine, but when I compile the contract with Injected Web3 there is a problem.

Adding a user (with add_user) it's all okay, but when i try to remove a user, i get an error: callback contain no result Error: Out of gas

After some test i supposed that error is given when I try to set a uint value to zero.

Then I try to change the 0 in

userRegister[_hc].active=0;

with 9(or other int number)

userRegister[_hc].active=9; 

And all works fine.

So, someone can tell me what's wrong with set a uint value to 0? And how i can re-set a uint variable to zero? Thanks

Answer 1

Summary

This somehow seems to be a problem with Browser Solidity interacting with geth. When I deploy the contract and execute the transactions directly in geth, the contract works as expected.

@PietroR91, please submit your code as an issue in the Browser Solidity github. If you are unable to do so, I can do it later.

---

Details

Environment

The error in Browser Solidity has been verified with the pragma and compiler being ^0.4.0, ^0.4.4 and ^0.4.7.

The geth environment I am using is version 1.5.5-stable on OS/X.

Modified Source Code

Here is your source code, modified by the addition of getUser(...) to check the values of the data in the mapping, and some minor formatting changes:

pragma solidity ^0.4.0;

contract Test {
    struct User {
        string name;
        string surname;
        uint active;
    }

    mapping (bytes32 => User) public userRegister;

    function add_user(string _name, string _surname) {
        bytes32 _hc = sha3(_name, _surname);
        User p = userRegister[_hc];
        p.name = _name;
        p.surname = _surname;
        p.active = 1;
    }

    function remove(string _name, string _surname)  {
        bytes32 _hc = sha3(_name, _surname);
        userRegister[_hc].active = 0;
    }

    function active(string _name, string _surname)  {
        bytes32 _hc=sha3(_name, _surname);
        userRegister[_hc].active = 1;
    }

    function getUser(string _name, string _surname) constant
      returns (string name, string surname, uint256 active) {
        bytes32 _hc = sha3(_name, _surname);
        name = userRegister[_hc].name;
        surname = userRegister[_hc].surname;
        active = userRegister[_hc].active;
    }
}

Browser Solidity - Deploy And Execute add_user(...)

Browser Solidity - Attempt To Execute remove(...)

When attempting to execute remove(...) in Browser Solidity, the message callback contain no result Error: Intrinsic gas too low is displayed.

Browser Solidity - Web3 Deploy

Following is the Web3 Deploy code from Browser Solidity:

var testContract = web3.eth.contract([{"constant":true,"inputs":[{"name":"","type":"bytes32"}],"name":"userRegister","outputs":[{"name":"name","type":"string"},{"name":"surname","type":"string"},{"name":"active","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"_name","type":"string"},{"name":"_surname","type":"string"}],"name":"add_user","outputs":[],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"_name","type":"string"},{"name":"_surname","type":"string"}],"name":"remove","outputs":[],"payable":false,"type":"function"},{"constant":true,"inputs":[{"name":"_name","type":"string"},{"name":"_surname","type":"string"}],"name":"getUser","outputs":[{"name":"name","type":"string"},{"name":"surname","type":"string"},{"name":"active","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"_name","type":"string"},{"name":"_surname","type":"string"}],"name":"active","outputs":[],"payable":false,"type":"function"}]);
var test = testContract.new(
   {
     from: web3.eth.accounts[0], 
     data: '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', 
     gas: '4700000'
   }, function (e, contract){
    console.log(e, contract);
    if (typeof contract.address !== 'undefined') {
         console.log('Contract mined! address: ' + contract.address + ' transactionHash: ' + contract.transactionHash);
    }
 })

Deploying The Contract In geth

I paste the Web3 Deploy code from the previous section into my Dev geth console:

I0106 08:17:04.067480 internal/ethapi/api.go:1045] Tx(0x2ce868c7e3377f4330ef847747b471c5ff27384b67e973fff2c86f3547316db6) created: 0x22718021ba1f0ce28931c3d0653f624c6b409763
null [object Object]
undefined
...
null [object Object]
Contract mined! address: 0x22718021ba1f0ce28931c3d0653f624c6b409763 transactionHash: 0x2ce868c7e3377f4330ef847747b471c5ff27384b67e973fff2c86f3547316db6

Executing The Functions In geth

I then executed the following functions in geth:

> test.add_user("test_name", "test_surname", {from: eth.accounts[0], gas: 400000});
I0106 08:19:07.999559 internal/ethapi/api.go:1047] Tx(0xda430dd968ce3537ed29b4e57ff6f10a4feb6fb674ac1f50ac5684368b9415c1) to: 0x22718021ba1f0ce28931c3d0653f624c6b409763
"0xda430dd968ce3537ed29b4e57ff6f10a4feb6fb674ac1f50ac5684368b9415c1"
...
> eth.getTransactionReceipt("0xda430dd968ce3537ed29b4e57ff6f10a4feb6fb674ac1f50ac5684368b9415c1")
{
  blockHash: "0x02e8f2b1385bafb4336a8057640967763e05ad430c47a169ce0512f5e3bc9859",
  blockNumber: 5878,
  contractAddress: null,
  cumulativeGasUsed: 85340,
  from: "0x000d1009bd8f0b1301cc5edc28ed1222a3ce671e",
  gasUsed: 85340,
  logs: [],
  logsBloom: "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
  root: "0x28b34cf11c24cc9dc72ea47539b556ce8266fa5d4bed8910da24783019e6f9cb",
  to: "0x22718021ba1f0ce28931c3d0653f624c6b409763",
  transactionHash: "0xda430dd968ce3537ed29b4e57ff6f10a4feb6fb674ac1f50ac5684368b9415c1",
  transactionIndex: 0
}

Checking the function got executed correctly:

> test.getUser("test_name", "test_surname");
["test_name", "test_surname", 1]

Let's now execute the remove(...) function with the problem:

> test.remove("test_name", "test_surname", {from: eth.accounts[0], gas: 400000});
I0106 08:22:30.226885 internal/ethapi/api.go:1047] Tx(0x684c27aac5ff70c97c374646de9ec376ad2a2b67c7e0205445ed208b1b95b30b) to: 0x22718021ba1f0ce28931c3d0653f624c6b409763
"0x684c27aac5ff70c97c374646de9ec376ad2a2b67c7e0205445ed208b1b95b30b"
...
> eth.getTransactionReceipt("0x684c27aac5ff70c97c374646de9ec376ad2a2b67c7e0205445ed208b1b95b30b")
{
  blockHash: "0x895f68c8d0aa3adf2ec86e22ddc4f7ca9b185252258374430ff96988646ae7a0",
  blockNumber: 5899,
  contractAddress: null,
  cumulativeGasUsed: 14828,
  from: "0x000d1009bd8f0b1301cc5edc28ed1222a3ce671e",
  gasUsed: 14828,
  logs: [],
  logsBloom: "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
  root: "0x4f21b21ed39fc110bc8c2e9e5ac3be3576c1733c59660f728bd180273dd16210",
  to: "0x22718021ba1f0ce28931c3d0653f624c6b409763",
  transactionHash: "0x684c27aac5ff70c97c374646de9ec376ad2a2b67c7e0205445ed208b1b95b30b",
  transactionIndex: 0
}

Checking the function got executed correctly:

> test.getUser("test_name", "test_surname");
["test_name", "test_surname", 0]

---

An Interesting Observations

If I modify remove(...) to add the following:

function remove(string _name, string _surname)  {
    bytes32 _hc = sha3(_name, _surname);
    userRegister[_hc].name = _name;
    userRegister[_hc].surname = _surname;
    userRegister[_hc].active = 0;
}

I am able to execute the function in Browser Solidity, but the returned from getUser(...) shows that the value of active is not modified from 1 to 0.

Executing The Modified remove(...) function in Browser Solidity

The following screen shows the remove(...) function being successfully executed in Browser Solidity:

Following is the transaction receipt in geth:

> eth.getTransactionReceipt("0x59734b415f6e1094f57b07579cfaba53325321f1cee9512c84c4b257ed222d3c")
{
  blockHash: "0x91949c01a0bf15a8d8cf558b9e9afcda686855669960c5aaf46069d9d75d5c82",
  blockNumber: 5949,
  contractAddress: null,
  cumulativeGasUsed: 85468,
  from: "0x000d1009bd8f0b1301cc5edc28ed1222a3ce671e",
  gasUsed: 85468,
  logs: [],
  logsBloom: "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
  root: "0x2bf9db658636a8de8af1d4f171c8b8ea97d11bf55592d0fce67b69f3947719a6",
  to: "0x49472fa49f6e3e84c0c038416f000eaeddb5c891",
  transactionHash: "0x59734b415f6e1094f57b07579cfaba53325321f1cee9512c84c4b257ed222d3c",
  transactionIndex: 0
}

The following screen shows the second invocation of getUser(...) where the results are unchanged. active is still 1 instead of the expected 0: