Seven instructive examples how to use Boost Spirit

regex.cpp

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+// Example how to use C++11 <regex> and Boost.Regex
+
+#include <iostream>
+
+/******************************************************************************/
+// use std::regex to find a date in a string
+
+#include <regex>
+
+void std_regex() {
+    std::string str = "C++ Meetup on 2018-09-12 about String Parsing";
+
+    // simple regex match: "on ####-##-##"
+    std::regex re1("on ([0-9]{4}-[0-9]{2}-[0-9]{2})");
+
+    if (std::regex_search(str, re1)) {
+        std::cout << "std::regex_search() with re1: matched!" << std::endl;
+    }
+    else {
+        std::cout << "std::regex_search() with re1: no match!" << std::endl;
+    }
+
+    if (std::regex_match(str, re1)) {
+        std::cout << "std::regex_match() with re1: matched!" << std::endl;
+    }
+    else {
+        std::cout << "std::regex_match() with re1: no match!" << std::endl;
+    }
+
+    // regex match and std::string captures
+    std::smatch match;
+
+    if (std::regex_search(str, match, re1)) {
+        std::cout << "std::regex_search() with re1: matched!" << std::endl
+                  << "  match.size() = " << match.size() << std::endl
+                  << "  match[0] = " << match[0] << std::endl
+                  << "  match[1] = " << match[1] << std::endl;
+    }
+    else {
+        std::cout << "std::regex_search() with re1: no match!" << std::endl;
+    }
+
+    // Also: std::cmatch for const char* captures
+    const char* cstr = "Hello on 2018-09-13";
+    std::cmatch cmatch;
+
+    if (std::regex_search(cstr, cmatch, re1)) {
+        std::cout << "std::regex_search() with re1: matched!" << std::endl
+                  << "  match.size() = " << cmatch.size() << std::endl
+                  << "  match[0] = " << cmatch[0] << std::endl
+                  << "  match[1] = " << cmatch[1] << std::endl;
+    }
+    else {
+        std::cout << "std::regex_search() with re1: no match!" << std::endl;
+    }
+
+    // use regex_replace and construct a new string
+    std::string result = std::regex_replace(str, re1, "TODAY");
+    std::cout << "std::regex_replace() result = " << result << std::endl;
+}
+
+/******************************************************************************/
+// alternative: use Boost.Regex
+
+#include <boost/regex.hpp>
+
+void boost_regex() {
+    std::string str = "C++ Meetup on 2018-09-12 about String Parsing";
+
+    // simple regex match
+    boost::regex re1("on ([0-9]{4}-[0-9]{2}-[0-9]{2})");
+
+    if (boost::regex_search(str, re1)) {
+        std::cout << "boost::regex_search() with re1: matched!" << std::endl;
+    }
+    else {
+        std::cout << "boost::regex_search() with re1: no match!" << std::endl;
+    }
+
+    if (boost::regex_match(str, re1)) {
+        std::cout << "boost::regex_match() with re1: matched!" << std::endl;
+    }
+    else {
+        std::cout << "boost::regex_match() with re1: no match!" << std::endl;
+    }
+
+    // regex match and std::string captures
+    boost::smatch match;
+
+    if (boost::regex_search(str, match, re1)) {
+        std::cout << "boost::regex_search() with re1: matched!" << std::endl
+                  << "  match.size() = " << match.size() << std::endl
+                  << "  match[0] = " << match[0] << std::endl
+                  << "  match[1] = " << match[1] << std::endl;
+    }
+    else {
+        std::cout << "boost::regex_search() with re1: no match!" << std::endl;
+    }
+
+    // also: boost::cmatch for const char* captures, and regex_replace.
+}
+
+/******************************************************************************/
+// Note: I usually make a "compatibility" include which defines
+
+#if (__cplusplus >= 201103L)
+
+using std::regex_search;
+// ... and other symbols
+
+#else
+
+// or import from Boost
+using boost::regex_search;
+
+#endif
+
+/******************************************************************************/
+
+int main()
+{
+    std_regex();
+    boost_regex();
+
+    return 0;
+}
+
+/******************************************************************************/