Solidity – Maximum Value an Int and Uint Can Store

To convert one type to another, use uint(x) or int(x). The rules are basically the same as in C, where the first bit of the uint becomes the sign.

For example:

if (int(a - b) < c) doSomething();

is likely what you want, as the numbers will be subtracted, then converted.

The type(x) syntax is used for all kinds of casting, such as truncating a number (uint8(someUint)), converting to and from odd types (bytes32(someUint)), or even casting a given address to a specific contract type (someContract(someAddress)).

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: