Data Location Assignment

SAINTPATRICK · January 30, 2023, 12:14am

change memory to storage

Stormingfox · January 30, 2023, 12:19am

Chatgpt gave me this:

    function updateBalance(uint id, uint balance) public {
         users[id].balance = balance;
    }

However setting the memory data location to storage, makes overall more sense to me:

function updateBalance(uint id, uint balance) public {
         User storage user = users[id];
         user.balance = balance;
    }

The first example costs slightly less in gas fees however, which makes sense.

Stormingfox · January 30, 2023, 12:22am

Do you need help solving the problem?
I can see that this is just the original code.

krille1 · February 7, 2023, 4:28pm

Hi guys!

So I solved the assignment by changing data location to storage in the updateBalance function

pragma solidity 0.8.7;

contract MemoryAndStorage {

    mapping(uint => User) users;

    struct User{

        uint id;

        uint balance;

    }

    function addUser(uint id, uint balance) public {

        users[id] = User(id, balance);

    }

    function updateBalance(uint id, uint balance) public {

         User storage user = users[id];

         user.balance = balance;

    }

    function getBalance(uint id) view public returns (uint) {

        return users[id].balance;

    }

}

mariustoft · February 8, 2023, 1:30pm

I solved it in 2 ways:
1: Replacing memory with storage.

pragma solidity 0.8.17;
contract MemoryAndStorage {

    mapping(uint => User) users;

    struct User{
        uint id;
        uint balance;
    }

    function addUser(uint id, uint balance) public {
        users[id] = User(id, balance);
    }

    function updateBalance(uint id, uint balance) public {
         User storage user = users[id];
         user.balance = balance;
    }

    function getBalance(uint id) view public returns (uint) {
        return users[id].balance;
    }

}

2: Reusing code from function addUser. Thus adding user with that number with the desired balance.

pragma solidity 0.8.17;
contract MemoryAndStorage {

    mapping(uint => User) users;

    struct User{
        uint id;
        uint balance;
    }

    function addUser(uint id, uint balance) public {
        users[id] = User(id, balance);
    }

    function updateBalance(uint id, uint balance) public {
         users[id] = User(id, balance);
    }

    function getBalance(uint id) view public returns (uint) {
        return users[id].balance;
    }

}

Tony_Siu · February 21, 2023, 1:25pm

pragma solidity 0.7.5;
contract MemoryAndStorage {

    mapping(uint => User) users;

    struct User{
        uint id;
        uint balance;
    }

    function addUser(uint id, uint balance) public {
        users[id] = User(id, balance);
    }

    function updateBalance(uint id, uint balance) public {
         users[id].balance = balance;
    }

    function getBalance(uint id) view public returns (uint) {
        return users[id].balance;
    }

}

EngrPips · March 2, 2023, 11:06pm

this is my solution

pragma solidity 0.7.5;
contract MemoryAndStorage {

mapping(uint => User) users;

struct User{
    uint id;
    uint balance;
}

function addUser(uint id, uint balance) public {
    users[id] = User(id, balance);
}

function updateBalance(uint id, uint balance) public {
     User memory user = users[id];
     user.balance = balance;
    users[id] = user;
}

function getBalance(uint id) view public returns (uint) {
    return users[id].balance;
}

}

kingofnowhere · March 5, 2023, 8:12am

pragma solidity 0.7.5;
contract MemoryAndStorage {

    mapping(uint => User) users;

    struct User{
        uint id;
        uint balance;
    }

    function addUser(uint id, uint balance) public {
        users[id] = User(id, balance);
    }

    function updateBalance(uint id, uint balance) public {
         users[id].balance = balance;
    }

    function getBalance(uint id) view public returns (uint) {
        return users[id].balance;
    }

}

emmanuelcooke · March 16, 2023, 11:41am

pragma solidity =< 0.8.17;

contract MemoryAndStorage {

mapping(uint --> User) users;

struct User{

    uint id;

    uint balance;

}

function addUser(uint id, uint balance) public {

    users[id] = User(id, balance);

}

function updateBalance(uint id, uint balance) memory public {

    User user = users[id];

    user balance = balance;

}

function getBalance(uint id) view public returns (uint) {

    return users[id] balance;

}

}

giriniem · March 18, 2023, 11:16am

pragma solidity 0.7.5;
contract MemoryAndStorage {

mapping(uint => User) users;

struct User{
uint id;
uint balance;
}

function addUser(uint id, uint balance) public {
users[id] = User(id, balance);
}

function updateBalance(uint id, uint balance) public {
User storage user = users[id];
user.balance = balance;
}

function getBalance(uint id) view public returns (uint) {
return users[id].balance;
}

}

gilbmporto · March 22, 2023, 7:25pm

There goes my simple solution:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.2;

contract MemoryAndStorage {

    mapping(uint => User) users;

    struct User{
        uint id;
        uint balance;
    }

    function addUser(uint id, uint balance) public {
        users[id] = User(id, balance);
    }

    function updateBalance(uint id, uint balance) public {
        require(users[id].id != 0, "This user doesn't exist");
        users[id].balance = balance;
    }

    function getBalance(uint id) view public returns (uint) {
        return users[id].balance;
    }

}

Ghosty126 · May 9, 2023, 3:10pm

function updateBalance(uint id, uint balance) public {
         User storage user = users[id];
         user.balance = balance;
    }

Mihir · June 8, 2023, 2:56pm

function updateBalance(uint id, uint balance) public {

         //User memory user = users[id];

         users[id].balance = balance;

    }

Ahmad_Abd_Allah · June 14, 2023, 2:11pm

// SPDX-License-Identifier: MIT
pragma solidity 0.8.20;

contract MemoryAndStorage {

mapping(uint => User) users;

    struct User{
        uint id;
        uint balance;
    }

    function addUser(uint id, uint balance) public {
        users[id] = User(id, balance);
    }

    function updateBalance(uint id, uint balance) public {
         User storage user = users[id];
         user.balance = balance;
    }

    function getBalance(uint id) view public returns (uint) {
        return users[id].balance;
    }

paradox · August 11, 2023, 4:17pm

Replace lines 17 and 18 with this: users[id].balance = balance

MauricioNoriega · October 25, 2023, 10:15pm

I simply changed the memory variable to storage so it’s so longer a temporary storage in memory.

pragma solidity 0.7.5;
contract MemoryAndStorage {

    mapping(uint => User) users;

    struct User{
        uint id;
        uint balance;
    }

    function addUser(uint id, uint balance) public {
        users[id] = User(id, balance);
    }

    function updateBalance(uint id, uint balance) public {
         User storage user = users[id];
         user.balance = balance;
    }

    function getBalance(uint id) view public returns (uint) {
        return users[id].balance;
    }

}

MrSeven · December 8, 2023, 3:53am

Here is my solution. Basically, just changing ‘memory’ to ‘storage’ does the trick.

// SPDX-License-Identifier: MIT
pragma solidity 0.7.5;
contract MemoryAndStorage {

    mapping(uint => User) users;

    struct User{
        uint id;
        uint balance;
    }

    function addUser(uint id, uint balance) public {
        users[id] = User(id, balance);
    }

    function updateBalance(uint id, uint balance) public {
         User storage user = users[id];
         user.balance = balance;
    }

    function getBalance(uint id) view public returns (uint) {
        return users[id].balance;
    }

}

Creator3168 · March 29, 2024, 5:01pm

pragma solidity 0.7.5;
contract MemoryAndStorage {

mapping(uint => User) users;

struct User{
    uint id;
    uint balance;
}

function addUser(uint id, uint balance) public {
    users[id] = User(id, balance);
}

function updateBalance(uint id, uint balance) public {
     User storage user = users[id];
     user.balance = balance;
}

function getBalance(uint id) view public returns (uint) {
    return users[id].balance;
}

}

Leo · April 15, 2024, 1:55pm

pragma solidity 0.8.24;

contract MemoryAndStorage {

    mapping(uint => User) users;

    struct User{

        uint id;

        uint balance;

    }

    function addUser(uint id, uint balance) public {

        users[id] = User(id, balance);

    }

    function updateBalance(uint id, uint balance) public {

         users[id].balance = balance;

    }

    function getBalance(uint id) view public returns (uint) {

        return users[id].balance;

    }

}
        uint balance;
    }

    function addUser(uint id, uint balance) public {
        users[id] = User(id, balance);
    }

    function updateBalance(uint id, uint balance) public {
         users[id].balance = balance;
    }

    function getBalance(uint id) view public returns (uint) {
        return users[id].balance;
    }

}

withjords · May 25, 2024, 4:33am

pragma solidity 0.7.5;
contract MemoryAndStorage {

    mapping(uint => User) users;

    struct User{
        uint id;
        uint balance;
    }

    function addUser(uint id, uint balance) public {
        users[id] = User(id, balance);
    }

    function updateBalance(uint id, uint balance) public {
         User storage user = users[id];
         user.balance = balance;
    }

    function getBalance(uint id) view public returns (uint) {
        return users[id].balance;
    }

}