Rust Lifetimes

Lifetimes define the duration for which an reference is going to be valid
All references in Rust have a lifetimes which is inferred implicitly
Sometimes lifetimes (similar to datatypes) cannot be implied so we need to mention the lifetimes explicitly

With lifetimes the goal to be prevent dangling references

fn main() {
    let r;
 
    {
        let x = 5;
        r = &x;
    }
 
    println!("r: {}", r);
}

In the above code the variable r is assigned a reference to the value of x in the inner scope
So when we reach the print statement which is in the other scope the variable r does not have a valid value.