使用正则表达式从字符串中提取4位数字？

import re

string = "This is a string with 1234 and 5678."
matches = re.findall(r'\b\d{4}\b', string)
print(matches)  # Output: ['1234', '5678']

const string = "This is a string with 1234 and 5678.";
const regex = /\b\d{4}\b/g;
const matches = string.match(regex);
console.log(matches);  // Output: ['1234', '5678']

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Main {
    public static void main(String[] args) {
        String string = "This is a string with 1234 and 5678.";
        Pattern pattern = Pattern.compile("\\b\\d{4}\\b");
        Matcher matcher = pattern.matcher(string);
        
        while (matcher.find()) {
            System.out.println(matcher.group());
        }
        // Output: 1234
        //         5678
    }
}