Passing a string by reference and manipulate the string

Question

I am trying to pass a string by reference and manipulate the string in the function:

fn manipulate(s: &mut String) {                                                                                                                                                                                                          
  // do some string manipulation, like push
  s.push('3');  // error: type `&mut collections::string::String` 
                // does not implement any method in scope named `push`
}

fn main() {
  let mut s = "This is a testing string".to_string();
  manipulate(&s);          
  println!("{}", s);       
}

I have looked at examples on borrowing and mutibility. Also tried (*s).push('3'), but got

error: type `collections::string::String` does not implement any method in scope named `push`

I'm sure there's something obvious I'm missing or perhaps more reference material to read, but I'm not sure how to proceed. Thanks!

Answer 1

Your code works with a slight modification on the newest version of rustc.

fn manipulate(s: &mut String) {                                                                                                                                                                                                          
  s.push('3');
}

fn main() {
  let mut s = "This is a testing string".to_string();
  manipulate(&mut s);          
  println!("{}", s);       
}