rust count occurrences of a substring

To count the occurrences of a substring in Rust, you can use the matches method from the str type. Here's an example:

fn count_substring_occurrences(string: &str, substring: &str) -> usize {
    string.matches(substring).count()
}

fn main() {
    let string = "Hello, hello, hello!";
    let substring = "hello";
    let count = count_substring_occurrences(string, substring);
    println!("The substring '{}' occurs {} times in the string.", substring, count);
}

In this example, the count_substring_occurrences function takes two parameters: string and substring. It uses the matches method to find all occurrences of the substring in the string and returns the count.

The main function demonstrates how to use the count_substring_occurrences function by counting the occurrences of the substring "hello" in the string "Hello, hello, hello!" and printing the result.

Please let me know if you need further assistance!