C++:
Using regular expressions
How to:
C++11 introduced support for regular expressions in the standard library, <regex>, offering a robust framework for string searching and manipulation. Here’s a basic example of using regular expressions to search for a pattern within a string:
#include <iostream>
#include <regex>
int main() {
std::string target = "Hello, my email is [email protected]";
std::regex email_pattern(R"(\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}\b)");
if (std::regex_search(target, email_pattern)) {
std::cout << "Email found!" << std::endl;
} else {
std::cout << "No email found." << std::endl;
}
return 0;
}Sample Output
Email found!For more complex manipulations, such as replacing patterns within strings, C++’s regular expressions can be very handy:
#include <iostream>
#include <regex>
int main() {
std::string text = "The rain in Spain falls mainly in the plain.";
std::regex vowel_regex("([aeiou])");
std::string replaced_text = std::regex_replace(text, vowel_regex, "*");
std::cout << replaced_text << std::endl;
return 0;
}Sample Output
Th* r**n *n Sp**n f*lls m**nly *n th* pl**n.For programmers exploring beyond the standard library, the Boost Regex library (boost/regex.hpp) is a popular third-party option offering enhanced regex capabilities and performance optimizations, particularly for complex patterns or extensive data processing:
#include <iostream>
#include <boost/regex.hpp>
int main() {
std::string s = "Boost libraries are fun!";
boost::regex expr("(\\w+)\\s(libraries)"); // Match "Boost libraries"
std::string fmt("GNU \\1"); // Replace with "GNU Boost"
std::string result = boost::regex_replace(s, expr, fmt);
std::cout << result << std::endl;
return 0;
}Sample Output
GNU Boost are fun!These examples scratch the surface of C++’s capabilities with regular expressions, illustrating basic searches, pattern matching, and replacements, either using the standard library or enhanced by Boost’s powerful regex implementation.