> For the complete documentation index, see [llms.txt](https://metaversenw.gitbook.io/metaversenetwork/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://metaversenw.gitbook.io/metaversenetwork/bit.country-metaverse-whitepaper/developers/wasm/create-a-flipper-contract.md).

# Create a Flipper Contract

There are two ways you can create a flipper contract. 

1. Create a contract from scratch
2. Use cargo-contract to generate a flipper contract as example

Let's get started!

### 1. Create from scratch

You can refer to this Flipper contract [code example. ](https://github.com/paritytech/ink/blob/v4.0.0/examples/flipper/lib.rs)

Create new folder, run `cargo init flipper`[ ](https://github.com/paritytech/ink/blob/v4.0.0/examples/flipper/lib.rs)then copy this code to lib.rs

```rust
#![cfg_attr(not(feature = "std"), no_std)]

#[ink::contract]
pub mod flipper {
    #[ink(storage)]
    pub struct Flipper {
        value: bool,
    }

    impl Flipper {
        /// Creates a new flipper smart contract initialized with the given value.
        #[ink(constructor)]
        pub fn new(init_value: bool) -> Self {
            Self { value: init_value }
        }

        /// Creates a new flipper smart contract initialized to `false`.
        #[ink(constructor)]
        pub fn new_default() -> Self {
            Self::new(Default::default())
        }

        /// Flips the current value of the Flipper's boolean.
        #[ink(message)]
        pub fn flip(&mut self) {
            self.value = !self.value;
        }

        /// Returns the current value of the Flipper's boolean.
        #[ink(message)]
        pub fn get(&self) -> bool {
            self.value
        }
    }

    #[cfg(test)]
    mod tests {
        use super::*;

        #[ink::test]
        fn default_works() {
            let flipper = Flipper::new_default();
            assert!(!flipper.get());
        }

        #[ink::test]
        fn it_works() {
            let mut flipper = Flipper::new(false);
            assert!(!flipper.get());
            flipper.flip();
            assert!(flipper.get());
        }
    }

    #[cfg(all(test, feature = "e2e-tests"))]
    mod e2e_tests {
        use super::*;
        use ink_e2e::build_message;

        type E2EResult<T> = std::result::Result<T, Box<dyn std::error::Error>>;

        #[ink_e2e::test]
        async fn it_works(mut client: ink_e2e::Client<C, E>) -> E2EResult<()> {
            // given
            let constructor = FlipperRef::new(false);
            let contract_acc_id = client
                .instantiate("flipper", &ink_e2e::alice(), constructor, 0, None)
                .await
                .expect("instantiate failed")
                .account_id;

            let get = build_message::<FlipperRef>(contract_acc_id.clone())
                .call(|flipper| flipper.get());
            let get_res = client.call_dry_run(&ink_e2e::bob(), &get, 0, None).await;
            assert!(matches!(get_res.return_value(), false));

            // when
            let flip = build_message::<FlipperRef>(contract_acc_id.clone())
                .call(|flipper| flipper.flip());
            let _flip_res = client
                .call(&ink_e2e::bob(), flip, 0, None)
                .await
                .expect("flip failed");

            // then
            let get = build_message::<FlipperRef>(contract_acc_id.clone())
                .call(|flipper| flipper.get());
            let get_res = client.call_dry_run(&ink_e2e::bob(), &get, 0, None).await;
            assert!(matches!(get_res.return_value(), true));

            Ok(())
        }

        #[ink_e2e::test]
        async fn default_works(mut client: ink_e2e::Client<C, E>) -> E2EResult<()> {
            // given
            let constructor = FlipperRef::new_default();

            // when
            let contract_acc_id = client
                .instantiate("flipper", &ink_e2e::bob(), constructor, 0, None)
                .await
                .expect("instantiate failed")
                .account_id;

            // then
            let get = build_message::<FlipperRef>(contract_acc_id.clone())
                .call(|flipper| flipper.get());
            let get_res = client.call_dry_run(&ink_e2e::bob(), &get, 0, None).await;
            assert!(matches!(get_res.return_value(), false));

            Ok(())
        }
    }
}
```

### 2. Use cargo-contract to generate a flipper contract as example

Create a new folder, then cd into your folder and run `cargo contract new flipper`

This command will create a new project folder named flipper

```
flipper
  └─ lib.rs                <-- Contract Source Code
  └─ Cargo.toml            <-- Rust Dependencies and ink! Configuration
  └─ .gitignore
```

### Compile Your Contract

Run the following command in your `flipper` directory to compile your smart contract:

`cargo contract build`

This command will build the following for your contract: a Wasm binary, a metadata file (which contains the contract's ABI) and a `.contract` file which bundles both. This `.contract` file can be used to deploy your contract to a chain. If all goes well, you should see a `target` folder which contains these files:

```
target
  └─ ink
    └─ flipper.contract
    └─ flipper.wasm
    └─ flipper.json
```

Let's take a look at the structure of the `flipper.json`:

```
{
  "source": {...},
  "contract": {...},
  "spec": {
    "constructors": [...],
    "docs": [],
    "events": [],
    "messages": [...],
  },
  "storage": {...},
  "types": [...],
  "version": "4"
}
```

This file describes all the interfaces that can be used to interact with your contract:

* `types` provides the custom **data types** used throughout the rest of the JSON.
* `storage` defines all the **storage** items managed by your contract and how to access them.
* `spec` stores information about the callable functions like **constructors** and **messages** a user can call to interact with the contract. It also has helpful information like the **events** emitted by the contract or any **docs**.