Create ex_23.cpp

ch17/ex_23.cpp

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+/***************************************************************************
+*  @file       main.cpp
+*  @author     Queequeg
+*  @date       26  Nov 2014
+*  @remark     This code is for the exercises from C++ Primer 5th Edition
+*  @note
+***************************************************************************/
+//!
+//! Exercise 17.21
+//! Rewrite your phone number program from 8.3.2 (p. 323) to use the 
+//! valid function defined in this section.
+
+#include<iostream>
+using std::cerr;
+using std::cout;
+using std::cin;
+using std::endl;
+using std::istream;
+using std::ostream;
+
+#include<fstream>
+using std::ifstream;
+using std::ofstream;
+
+#include<sstream>
+using std::istringstream;
+using std::ostringstream;
+
+#include<string>
+using std::string;
+
+#include<vector>
+using std::vector;
+
+#include <regex>
+using std::regex;
+using std::sregex_iterator;
+using std::regex_error;
+
+int main() {
+	try {
+		regex reg("(\\d{4})?([-])?(\\d{5})");
+		string str;
+		while (getline(cin, str)) {
+			for (sregex_iterator b(str.cbegin(), str.cend(), reg), e; b != e; ++b) {
+				if (!(*b)[1].matched) // if if there is only the last 5 digits of index
+					cout << b->str(3);  // show them
+				else
+					cout << b->str();   // show index entirely
+				cout << '\t';
+			}
+		}
+	}
+
+	catch (regex_error re) {
+		cout << re.what() << endl << re.code() << endl;
+	}
+
+	return 0;
+}