Anchor Program Basics

Anchor program structure and instruction handlers. Results appear in the same fence: same-line // comments when short, multiline // blocks below the sample when not.

declare_id

Program id constant from keypair.

// declare_id!("Fg6PaFpoGXkYsidMpWTK6W2BeZ7FEfcYkg476zPFsLnS");

#[program]

Module of instruction handlers.

// #[program]
// pub mod my_program {
//   pub fn initialize(ctx: Context<Initialize>) -> Result<()> { Ok(()) }
// }

Context Accounts

Handler receives Context<T> with validated accounts.

// pub fn ix(ctx: Context<MyIx>, amount: u64) -> Result<()> { ... }

Accounts Derive

#[derive(Accounts)] builds validators.

// #[derive(Accounts)]
// pub struct Initialize<'info> { ... }

Result

Anchor Result alias over ProgramResult with error conversion.

// Ok(()) // success

Init Account

init constraint creates account.

// #[account(init, payer = user, space = 8 + 32)]

Mut Signer

Signer and mut constraints.

// #[account(mut)]
// pub user: Signer<'info>

System Program

Program account type for system program.

// pub system_program: Program<'info, System>

Instruction Data

Handler args after Context are instruction data.

// pub fn set(ctx: Context<Set>, value: u64) -> Result<()>

State Write

Write through account account data wrappers.

// ctx.accounts.state.value = value;

Program Module Name

IDL names follow module/handlers.

// anchor build generates IDL/types

Cfg Feature Cpi

Optional cpi feature for CPI helpers.

// cpi = ["no-entrypoint"] patterns in Cargo.toml

Entry Silence

no-entrypoint feature for use as CPI crate.

// [features] no-entrypoint = []

Space Disc

8 byte discriminator + space for fields.

// space = 8 + std::mem::size_of::<MyState>()

Owner Check

Anchor checks account owner vs expected program.

// #[account(has_one = authority)]

Related

• Anchor Accounts Constraints - account validation
• Program Errors and Logs - error macros
• PDAs and Seeds - seeds in accounts

Stack versions: This page was written for Agave 4.1.1, Solana CLI 3.0.10, Anchor 0.32.1, Rust 1.91.1, and @solana/kit 7.0.0.