taking only a int from a text with int string in Rust-CodePudding

i need to take only the integer from a string like this "Critical: 3\r\n" , note that the value change everytime so i can't search for "3", i need to search for a generic int.

Thanks.

CodePudding user response：

Many ways to do it. There are already some answers. Here is one more approach:

let s = "Critical: 3\r\n";
let s_res = s.split(":").collect::<Vec<&str>>()[1].trim();
println!("s_res = {s_res:?}");   // "3"

In the above code s_res will be a string (&str). To convert that string to an integer, you can do something like this:

let n: isize = s_res.parse().expect("Failed to parse the integer!");    
println!("n = {n}");  // 3

Note that, depending on your needs, you might want to add some extra validations/asserts, in case you expect the pattern might change (for example, the number of colons not to be 1, etc.).

CodePudding user response：

Building on @AlexanderKrauze's comment the most common way to do so is using a regex, which lets you look for any pattern in a String:

let your_text = "Critical: 3\r\n";
let re = Regex::new(r"\d ").unwrap(); // matches any amount of consecutive digits
let result:Option<Match> = re.find(your_text);// returns the match
let number:u32 = result.map(|m| m.as_str().parse::<u32>().unwrap()).unwrap_or(0); // converts to int
print!("{}", number);

would be the code for that. Only one digit is r"\d".

More documentation is found here.

CodePudding user response：

You can use chars to get an iterator over the chars of a string, and then apply filter on that iterator to filter out only digits(is_digit).

fn main() {
    let my_str: String = "Critical: 3\r\n".to_owned();
    let digits: String = my_str.chars().filter(|char| char.is_digit(10)).collect();
    println!("{}", digits)
}