Data Types

Exercises

Boolean

// Something's missing. Fix the code so that it compiles.

fn main() {
    let is_morning = true;
    if is_morning {
        println!("Good morning!");
    }

    let // Finish the rest of this line
    if is_evening {
        println!("Good evening!");
    }
}

fn main() {
  let is_morning = true;
  if is_morning {
      println!("Good morning!");
  }

  let is_evening = true; // can also assign false
  if is_evening {
      println!("Good evening!");
  }
}

Unsigned int

// Do you really have that few friends?
// Assign the correct value to the variable.

fn main() {
    let number_of_friends: u32; // Don't change this line!
    number_of_friends = -1;
    println!("I have {} friends!", number_of_friends);
}

fn main() {
  let number_of_friends: u32;
  number_of_friends = 10; // any integer from 0 to 4294967295 is valid
  println!("I have {} friends!", number_of_friends);
}

Signed int

// Make this program compile by replacing the variable type.

fn main() {
    let number_of_stars: i32;
    // The Milky Way has more stars than can fit in a 32-bit integer type!
    number_of_stars = 400_000_000_000;
    println!("There are about {} stars in the Milky Way galaxy!", number_of_stars);
}

fn main() {
  let number_of_stars: i64;
  number_of_stars = 400_000_000_000;
  println!("There are about {} stars in the Milky Way galaxy!", number_of_stars);
}

Floating point numbers

// Assign the correct data types to the variables.

fn main() {
    let pi2: f32;
    pi2 = 3.14;
    println!("Pi is {}, correct to 2 decimal places.", pi2);

    // What if we want to be more precise with our floating-point numbers?

    let pi15: /* Give this variable a data type! */;
    pi15 = 3.141592653589793;
    println!("Pi is {}, correct to 15 decimal places.", pi15);
}

fn main() {
  let pi2: f32;
  pi2 = 3.14;
  println!("Pi is {}, correct to 2 decimal places.", pi2);

  let pi15: f64;
  pi15 = 3.141592653589793;
  println!("Pi is {}, correct to 15 decimal places.", pi15);
}

char

// Fill in the rest of the line that has code missing!

fn main() {
    let my_first_initial = 'C';

    if my_first_initial.is_alphabetic() {
        println!("Alphabetical!");
    } else if my_first_initial.is_numeric() {
        println!("Numerical!");
    } else {
        println!("Neither alphabetic nor numeric!");
    }

    let // Finish this line like the example! What's your favorite character?
    // Try a letter, try a number, try a special character, try a character
    // from a different language than your own, try an emoji!

    if your_character.is_alphabetic() {
        println!("Alphabetical!");
    } else if your_character.is_numeric() {
        println!("Numerical!");
    } else {
        println!("Neither alphabetic nor numeric!");
    }
}

fn main() {
  let my_first_initial = 'C';

  if my_first_initial.is_alphabetic() {
      println!("Alphabetical!");
  } else if my_first_initial.is_numeric() {
      println!("Numerical!");
  } else {
      println!("Neither alphabetic nor numeric!");
  }

  let your_character = '😃';

  if your_character.is_alphabetic() {
      println!("Alphabetical!");
  } else if your_character.is_numeric() {
      println!("Numerical!");
  } else {
      println!("Neither alphabetic nor numeric!");
  }
}

String types

// Make this program compile without changing the variable type!

fn main() {
    let answer: String = /* Your favorite color here */;
    println!("My current favorite color is {}", answer);
}

fn main() {
  let answer: String = "black".to_string();
  println!("My current favorite color is {}", answer);
}

Arrays

// Create an array with at least 10 elements in it.

fn main() {
    let a = /* Your array here */;

    if a.len() >= 10 {
        println!("Wow, that's a big array!");
    } 
}

fn main() {
  let a = [10, 9, 8, 7, 6, 5, 4, 3, 2, 1];
  
  if a.len() >= 10 {
      println!("Wow, that's a big array!");
  } 
}

Tuples

// Destructure the `cat` tuple so that the println will work.

fn main() {
    let cat = ("Furry McFurson", 3.5);
    let /* Your pattern here */ = cat;

    println!("{} is {} years old.", name, age);
}

fn main() {
  let cat = ("Furry McFurson", 3.5);
  let (name, age) = cat;

  println!("{} is {} years old.", name, age);
}

Type aliasing

// Add a type alias for our dogs so we can store their names and ages.

fn main() {
    type /* Finish this line */

    let dog1: Dog = (String::from("Albert"), 3);
    println!("My dog {} is {} years old.", dog1.0, dog1.1);

    let dog2: Dog = (String::from("Barker"), 5);
    println!("My other dog {} is {} years old.", dog2.0, dog2.1);
}

fn main() {
  type Dog = (String, u8);

  let dog1: Dog = (String::from("Albert"), 3);
  println!("My dog {} is {} years old.", dog1.0, dog1.1);

  let dog2: Dog = (String::from("Barker"), 5);
  println!("My other dog {} is {} years old.", dog2.0, dog2.1);
}