PACKAGES, CRATES, MODULES AND PATHS

• A package is a set of crates.
• In a package , we have at most one library crate and zero or more binary crates.
• Library crate are piece of codes that are not executable, they are codes that can be reused among different projects.
• Binary crates are programs you can compile to an executable that you can run.
•  A crate is a set of modules.
• A modules is a set of reusable codes.
• Paths is how you refer to modules inside a crate.
• Binary crates can be placed in src bin folder and in this way you can have multiple binary crates inside the same package,
• A new binary create can be created by using below command:

• cargo new --bin myapp

• You can create a library crate inside the myapp folder, with below command:

• cargo new --lib intutils

• You can go to the lib.rs file in src folder of library crate and add the the following block of code:

• pub mod addition{
     pub fn add(a: i32, b: i32) -> i32 {
        a + b
     }
  }
  
  pun mod subtraction {
     pub fn sub(a: i32, b: i32) -> i32 {
        a - b
     }
  }

• Then you will need to go to the Cargo.toml file add the crate into it like below:

• [package]
  name = "myapp"
  version = "0.1.0"
  edition = "2021"
  
  [dependencies]
  intutils = {path = "intutils"}

• Then you will go to the main.rs in src folder of binary crate and type in normal rust code like below

• #![deny(clippy::all)]
  use intutils::addition::add;
  use intutils::subtraction::sub;
  
  fn main(){
    let add1: i32= add(a:3, b:4);
    let sub1: i32 = sub(a:4, b:4);
    println!("Add: {}", add1);
    println!("Sub: {}", sub1);
  }