Lifetimes

Question 1

What is lifetime in Rust?

Answer 1

A lifetime is a construct the compiler (or more specifically, its borrow checker) uses to ensure all borrows are valid. Specifically, a variable’s lifetime begins when it is created and ends when it is destroyed. While lifetimes and scopes are often referred to together, they are not the same.

Question 2

Lifetime function constraints:

Answer 2

any reference must have an annotated lifetime.
any reference being returned must have the same lifetime as an input or be static.

Question 3

What does ‘static’ indicates

Answer 3

As a reference lifetime ‘static indicates that the data pointed to by the reference lives for the remaining lifetime of the running program. It can still be coerced to a shorter lifetime

Question 4

How to make variables ‘static’

Answer 4

There are two common ways to make a variable with ‘static lifetime, and both are stored in the read-only memory of the binary:

Make a constant with the static declaration.
Make a string literal which has type: &’static str.