Address Types

One type, which is very specific to Ethereum and Solidity, is the type “address”.

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Ethereum supports transfer of Ether and communication between Smart Contracts. Those reside on an address. Addresses can be stored in Smart Contracts and can be used to transfer Ether from the Smart Contract to to an address stored in a variable.

That’s where variables of the type address come in.

In general, a variable of the type address holds 20 bytes. That’s all that happens internally. Let’s see what we can do with Solidity and addresses.

Smart Contract Example

Let’s create a new Smart Contract to have an example.

// SPDX-License-Identifier: GPL-3.0
pragma solidity 0.8.1;
 
contract AddressExample {
    address public myAddress;
    
    function setAddress(address _address) public {
        myAddress = _address;
    }
    
    function getBalanceOfAccount() public view returns(uint) {
        return myAddress.balance;
    }
}

Deploy the Smart Contract with Remix to the JavaScript VM:

Let’s run the Smart Contract and get the balance of addresses programatically.

Run the Smart Contract

What we’re going to do is to access the address in the accounts-list programatically from within the Smart Contract. We will:

1. Copy the Address from the Accounts-List
2. Update the “myAddress” variable in the Smart Contract
3. Get the Balance of the address stored

Let’s copy your first address from the Accounts-List. Click the little “copy” icon next to your Account:

Then paste it into the input field next to “setAddress” and then click the “setAddress” button:

When you hit the “myAddress” button, it should show you your address:

Now, let’s check the balance, click on “getBalanceOfAccount” button and it should show you the balance in Wei:

Your balance will be very similar to the one in the picture above, probably around 99.999999-some Ether. Why not 100 Ether, or where do the Ether come from? The JavaScript VM is a simulated environment that will “give” you 100 Ether to play. Every transaction costs a little bit of Ether in Gas-Costs, which we will cover later.

Later on you will see how a Smart Contract can manage Ether which are sent to the address of the Smart Contract. Let’s discuss an example using Strings next!