Check if a string is empty or blank

Question

What's the proper way to check if a string is empty or blank for a) &str b) String? I used to do it by "aaa".len() == 0, but there should another way as my gut tells me?

Answer 1

Both &str and String have a method called is_empty:

• Documentation for &str::is_empty
• Documentation for String::is_empty

This is how they are used:

assert_eq!("".is_empty(), true); // a) assert_eq!(String::new().is_empty(), true); // b) 

Answer 2

Empty or whitespace only string can be checked with:

s.trim().is_empty() 

where trim() returns a slice with whitespace characters removed from beginning and end of the string (https://doc.rust-lang.org/stable/std/primitive.str.html#method.trim).