Problem set Numbers, Integer Problem 5. Vague questioning.

[delta549]

Problem set:

// Fix errors and panics to make it work
fn main() {
   let v1 = 251_u8 + 8;
   let v2 = i8::checked_add(251, 8).unwrap();
   println!("{},{}",v1,v2);
}

The vagueness of the question here may be a cause for concern for someone new to this concept. The fundamental issue is that:

the literal `251` does not fit into the type `i8` whose range is `-128..=127`

Resolving this error can be handled by either changing the arithmetic to fit within the bounds of a u8/i8. Or by increasing the type to an i16/u16. The question merely asks you to resolve this.

The solution given is:

fn main() {
    let v1 = 247_u8 + 8;
    let v2 = i8::checked_add(119, 8).unwrap();
    println!("{},{}",v1,v2);
 }

Here the solution is to reduce the unsigned integer u8:

• From 251 to 247 = 255 (The maximum value of a u8)
• The signed i8 from (251, 8) to (119, 8) = 127 (The maximum positive value of an i8)

I believe here there should be a specific mention within the comment:
// Fix errors and panics to make it work

To change the values of the integers and not the integer types themselves. Something like:

// Fix errors and panics to make it work. 
// Do this by changing the values to the maximum allowed for an i8 and u8 respectively.

Or

// Fix errors and panics to make it work. Without changing the type!.

Hopefully this will give the learner the specific scope to answer the question and get the solution provided.