How to Change the Values of a Person in Your Rust Program

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# How to Change the Values of a Person in Your Rust Program

What the reader will be able to do: Modify the `name` and `age` values of a `Human` struct at runtime.

## Prerequisites
- Basic understanding of Rust structs and `fn main()` (from previous tutorials)
- Familiarity with `String` and `u32` types

## Steps

1. **Modify the struct initialization in `main()`**  
   Open `src/main.rs` and change the `person` struct values:
   ```rust
   let person = Human {
       name: String::from("Charlie"),
       age: 35,
   };
   ```

2. **Add user input to dynamically change values**  
   Replace the `main()` function with:
   ```rust
   use std::io;

   fn main() {
       println!("Enter your name:");
       let mut name = String::new();
       io::stdin()
           .read_line(&mut name)
           .expect("Failed to read line");

       println!("Enter your age:");
       let mut age_input = String::new();
       io::stdin()
           .read_line(&mut age_input)
           .expect("Failed to read line");

       let age: u32 = age_input.trim().parse().expect("Please enter a valid number");

       let person = Human {
           name: name.trim().to_string(),
           age,
       };

       println!("Name: {}", person.name);
       println!("Age: {}", person.age);
   }
   ```

3. **Compile and run**  
   Run:
   ```bash
   cargo run
   ```
   Expected interaction:
   ```
   Enter your name:
   David
   Enter your age:
   40
   Name: David
   Age: 40
   ```

## Pitfalls
- Forgetting to call `.trim()` on input strings (leaves newline characters in the output)
- Not handling parsing errors with `.expect()` (causes crashes on invalid input)
- Using `String` instead of `&str` for input (requires explicit conversion)

## To go further
- Learn about Rust's `match` expressions for validating user input
- Explore how to create multiple `Human` instances in a loop