# CPI (Anchor) Build examples of CPI (Cross Program Invocation) `factory` program will invoke the `counter` program. Complete all tasks below - Implement the programs - Test locally # Update program id ```shell anchor keys sync ``` # Task 1 - Copy IDL Compile `counter` program ```shell anchor build ``` Create a new folder called `idls` under project root. ```shell mkdir idls ``` Copy `target/idl/counter.json` into `idls` ```shell cp target/idl/counter.json idls/ ``` # Task 2 - Import IDL of the `counter` program into [`lib.rs`](https://github.com/Cyfrin/solana-course/blob/main/apps/cpi/anchor/exercise/programs/factory/src/lib.rs) Import IDL of the `counter` program. ```rust declare_program!(counter); use counter::program::Counter; ``` # Task 3 - Implement [`init`](https://github.com/Cyfrin/solana-course/blob/main/apps/cpi/anchor/exercise/programs/factory/src/lib.rs) - Invoke the function `init` on the `counter` program ```rust let cpi_accounts = counter::cpi::accounts::Init { payer: ctx.accounts.payer.to_account_info(), counter: ctx.accounts.counter.to_account_info(), system_program: ctx.accounts.system_program.to_account_info(), }; let cpi_ctx = CpiContext::new( ctx.accounts.counter_program.to_account_info(), cpi_accounts, ); counter::cpi::init(cpi_ctx)?; ``` - Add `counter_program` into `Init` ```rust pub counter_program: Program<'info, Counter>, ``` # Task 4 - Implement [`inc`](https://github.com/Cyfrin/solana-course/blob/main/apps/cpi/anchor/exercise/programs/factory/src/lib.rs) - Invoke the function `inc` on the `counter` program ```rust let cpi_accounts = counter::cpi::accounts::Inc { counter: ctx.accounts.counter.to_account_info(), }; let cpi_ctx = CpiContext::new( ctx.accounts.counter_program.to_account_info(), cpi_accounts, ); counter::cpi::inc(cpi_ctx)?; ``` - Add `counter_program` into `Inc` ```rust pub counter_program: Program<'info, Counter>, ``` # Build ```shell anchor build ``` # Test ```shell anchor test ```