import re
text = "Date: 2025-10-31"
pattern = r"(?P<year>\d{4})-(?P<month>\d{2})-(?P<day>\d{2})" # Python uses ?P<name>
match = re.search(pattern, text)
if match:
    print(f"Year: {match.group('year')}")   # -> Year: 2025
    print(f"Month: {match.group('month')}") # -> Month: 10
    print(f"Day: {match.group('day')}")     # -> Day: 31

import re

text = "My email is example@example.com"
pattern = r"\w+@\w+\.\w+"  # 使用原始字符串 r"..." 避免反斜杠问题

# 查找第一个匹配项
match = re.search(pattern, text)
if match:
    print(f"Found: {match.group(0)}")  # 输出: Found: example@example.com

# 查找所有匹配项
emails = re.findall(pattern, text)
print(f"All emails: {emails}") # 输出: All emails: ['example@example.com']

# 替换
new_text = re.sub(pattern, "[REDACTED]", text)
print(new_text)  # 输出: My email is [REDACTED]

#include <iostream>
#include <string>
#include <regex>

int main() {
    std::string text = "My email is example@example.com";
    std::regex pattern("(\\w+)@(\\w+)\\.(\\w+)"); // C++中反斜杠需要双写

    std::smatch match;
    if (std::regex_search(text, match, pattern)) {
        std::cout << "Full match: " << match[0] << std::endl; // Full match: example@example.com
        std::cout << "User: " << match[1] << std::endl;       // User: example
        std::cout << "Domain: " << match[2] << std::endl;     // Domain: example
    }

    // 替换
    std::string new_text = std::regex_replace(text, pattern, "[REDACTED]");
    std::cout << new_text << std::endl; // My email is [REDACTED]

    return 0;
}

const text = "My email is example@example.com";
const pattern = /\w+@\w+\.\w+/g; // g 是全局匹配标志

// 查找匹配
const match = text.match(pattern);
console.log(match); // 输出: ["example@example.com"]

// 测试是否存在匹配
const hasEmail = pattern.test(text);
console.log(hasEmail); // true (注意：由于 g 标志和 lastIndex，多次调用 test 需重置)

// 替换
const newText = text.replace(pattern, "[REDACTED]");
console.log(newText); // 输出: My email is [REDACTED]

// 捕获组
const complexPattern = /(\w+)@(\w+)\.(\w+)/;
const parts = text.match(complexPattern);
if (parts) {
    console.log(`Full: ${parts[0]}, User: ${parts[1]}, Domain: ${parts[2]}`);
    // Full: example@example.com, User: example, Domain: example
}