CPI Basics in Anchor

use anchor_lang::system_program::{self, Transfer};
 
system_program::transfer(
    CpiContext::new(
        ctx.accounts.system_program.to_account_info(),
        Transfer {
            from: ctx.accounts.payer.to_account_info(),
            to: ctx.accounts.recipient.to_account_info(),
        },
    ),
    lamports,
)?;

use anchor_spl::token::{self, Transfer};
 
token::transfer(
    CpiContext::new(
        ctx.accounts.token_program.to_account_info(),
        Transfer {
            from: ctx.accounts.from_ata.to_account_info(),
            to: ctx.accounts.to_ata.to_account_info(),
            authority: ctx.accounts.authority.to_account_info(),
        },
    ),
    amount,
)?;

let seeds = &[b"vault".as_ref(), &[ctx.bumps.vault]];
let signer = &[&seeds[..]];
 
token::transfer(
    CpiContext::new_with_signer(
        ctx.accounts.token_program.to_account_info(),
        accounts,
        signer,
    ),
    amount,
)?;

let cpi_ctx = CpiContext::new(
    ctx.accounts.token_program.to_account_info(),
    transfer_accounts,
);
token::transfer(cpi_ctx.with_signer(signer), amount)?;

pub token_program: Program<'info, Token>,
pub system_program: Program<'info, System>,

// lib.rs
declare_program!(other_program);
 
pub fn call_other(ctx: Context<CallOther>) -> Result<()> {
    other_program::cpi::do_something(
        CpiContext::new(
            ctx.accounts.other_program.to_account_info(),
            other_program::cpi::accounts::DoSomething { /* ... */ },
        ),
    )?;
    Ok(())
}

let mut cpi_ctx = CpiContext::new(program, accounts);
cpi_ctx = cpi_ctx.with_remaining_accounts(ctx.remaining_accounts.to_vec());
other_program::cpi::advanced(cpi_ctx)?;

token::transfer(cpi_ctx, amount)
    .map_err(|_| MyError::TransferFailed)?;