A basic Anchor calculator program

anchor_calculator.rs

use anchor_lang::prelude::*;

declare_id!("Fg6PaFpoGXkYsidMpWTK6W2BeZ7FEfcYkg476zPFsLnS");

#[program]
pub mod anchor_calculator {
    use super::*; 

    pub fn add(ctx: Context<Calculator>, a: i64, b: i64) -> Result<()> {
        let result = a + b;
        msg!("Result: {}", result);
        Ok(())
    }

    pub fn subtract(ctx: Context<Calculator>, a: i64, b: i64) -> Result<()> {
        let result = a - b;
        msg!("Result: {}", result);
        Ok(())
    }

    pub fn multiply(ctx: Context<Calculator>, a: i64, b: i64) -> Result<()> {
        let result = a * b;
        msg!("Result: {}", result);
        Ok(())
    }

    pub fn divide(ctx: Context<Calculator>, a: i64, b: i64) -> Result<()> {
        if b == 0 {
            return err!(CalculatorError::DivisionByZero);
        }
        let result = a / b;
        msg!("Result: {}", result);
        Ok(())
    }
}

#[derive(Accounts)]
pub struct Calculator {}

#[error_code]
pub enum CalculatorError {
    #[msg("Division by zero is not allowed.")]
    DivisionByZero,
}