What are regular expressions, and what are their advantages and disadvantages to consider?

Regular expressions (regex) are patterns for searching and processing strings, allowing efficient finding, replacing, or validating text according to specified rules.

Advantages:

• Allow compact description of complex search patterns.
• Universal and supported in many programming languages.
• Can significantly speed up text processing compared to manual parsing.

Disadvantages:

• Complex expressions are hard to read and maintain.
• Can be slow if used improperly (e.g., excessive backtracking).
• Not always suitable for parsing nested or context-dependent structures.

Example in Java:

import java.util.regex.*;

public class RegexExample {
    public static void main(String[] args) {
        String text = "Email: example@test.com";
        String pattern = "[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,}";

        Pattern r = Pattern.compile(pattern);
        Matcher m = r.matcher(text);

        if (m.find()) {
            System.out.println("Found email: " + m.group(0));
        } else {
            System.out.println("Email not found");
        }
    }
}