First_DApp.md

First Dapp

For your first DApp nothing more convinient that an Hello World example.

C#

All Smart Contract on C# must be inherited from Framework.SmartContract.

C# template:

using ... // namespaces
namespace Neo.SmartContract
{
    public class Template : Framework.SmartContract
    {
        public static void Main()
        {
            // code
        }
    }
}

As you can see above, every smart contract on C# must have a Main function ( with or without params) as entry point!.

The Storage class handle the read and write inside the blockchain. Now for our first DApp we want to write the word World inside the key Hello.

Information: The smart contract can only change his storage, so everybody can read but only the SC can change. The storage is also a map that we store data ( value ) inside a key.

With all i talked about we can manage the code below:

using Neo.SmartContract.Framework.Services.Neo;

namespace Neo.SmartContract
{
    public class HelloWorld : Framework.SmartContract
    {
        public static void Main()
        {
            Storage.Put(Storage.CurrentContext, "Hello", "World");
        }
    }
}

So is that Simple and our first Dapp using C# is read to use.

The Put method handle the writing and the Get method handle the reading.

Python

In python the script is smaller and very simple.

Python template:

import ... # neo-boa modules

def Main():
    ... # code
    
                                            

Now we can use the method Put and GetContext to write data inside the blockchain using neo.

The first DApp in python is as follows:

from boa.interop.Neo.Storage import Put, GetContext

ctx = GetContext()

def Main():
    Put(ctx, 'Hello', 'World')                                

Back