# Program Examples

### :space_invader: Welcome, Solana Developer. :space_invader:   
   
Do you ever think to yourself: *"OK, but how do I do this on-chain?"*   
   
Or maybe you're in a hackathon right now, the clock's ticking, and you need to get a program off the ground *fast*.   
   
We present to you this list of curated examples for a wide range of use cases implemented using **on-chain programs**.   
   
### :link: All on-chain. :crab: All Rust. :muscle: All the time. 

## Some Basic Concepts to Know
Most system-level operations on Solana involve already-existing Solana programs.   
   
For example, to create a **system account** you use the **system program** and to create a **token mint** you use the **token program**.   
   
So, you'll notice that these operations are in fact conducting what's called a **cross-program invocation** - which is a fancy way of saying it calls other Solana programs to do business. You can see this in action whenever you see `invoke` or `invoke_signed` in the `native` examples, or `CpiContext` in the `anchor` examples.   
   
Deciding when to use cross-program invocation instead of invoking the programs directly from the client is completely up to you as the builder. It depends on how your application is designed.
- Maybe you want to add some checks - such as minimum balance required, allowed ownership, etc.
- Maybe you want to assert that an account has a certain data type.
- Perhaps you want to send only one transaction from your client for a handful of sequential operations.
- The list goes on.
Regardless of what you may want to add on top of existing Solana programs, the number one use case for writing your own program is for using accounts with a **Program Derived Address (PDA)**. Crack open the `pdas` folder to see why.

## Navigating this Repo

:file_folder: Each example contains two folders:
- `native` - Written using Solana's native Rust crates and vanilla Rust.
- `anchor` - Written using Anchor's `anchor_lang` Rust crate and the associated Anchor framework to build & deploy.

:wrench: How to build & run:
- Before running anything in any folder make sure you pull in the dependencies with `yarn install`.
- `native` - Use `cicd.sh` to build & deploy the program. Run `yarn run test` to test it.
- `anchor` - Use `anchor build && anchor deploy` to build & deploy the program. Run `anchor run test` to test it.