ex17_19_20.cpp

/***************************************************************************
*  @file       main.cpp
*  @author     Queequeg
*  @date       26  Nov 2014
*  @remark     This code is for the exercises from C++ Primer 5th Edition
*  @note       There are some bugs in gcc(include the latest version 4.9.2) 
*              to handle regular expression.To compile this program, please
*			   turn to other compilers such as msvs2013 and clang.
***************************************************************************/
//
// Exercise 17.19
// Why is it okay to call m[4].str() without first checking whether m[4] 
// was matched?
// We expect that the two delimiters in m[4] and m[6] are the same. 
// If m[4](or m[6]) is mismatched, m[4].str()(or m[6].str() respectively) 
// returns an empty string which can also be compared with the other
// delimiter. 

//
// Exercise 17.20
// Write your own version of the program to validate phone numbers.

#include <iostream>
using std::cout;
using std::cin;
using std::endl;

#include <string>
using std::string;

#include <regex>
using std::regex;
using std::sregex_iterator;
using std::smatch;

bool valid(const smatch& m);

int main()
{
	string phone = "(\\()?(\\d{ 3 })(\\))?([-. ])?(\\d{ 3 })([-. ]?)(\\d{ 4 })";
	regex r(phone);
	smatch m;
	string s;
	bool valid_record;
	// read each record from the input file
	while (getline(cin, s))
	{
		valid_record = false;
		// for each matching phone number
		for (sregex_iterator it(s.begin(), s.end(), r), end_it; it != end_it; ++it)
		{
			valid_record = true;
			// check whether the number's formatting is valid
			if (valid(*it))
				cout << "valid phone number: " << it->str() << endl;
			else
				cout << "invalid phone number: " << it->str() << endl;
		}

		if (!valid_record)
			cout << "invalid record!" << endl;
	}
	return 0;
}

bool valid(const smatch& m)
{
	// if there is an open parenthesis before the area code
	if (m[1].matched)
		// the area code must be followed by a close parenthesis
		// and followed immediately by the rest of the number or a space
		return m[3].matched && (m[4].matched == 0 || m[4].str() == " ");
	else
		// then there can't be a close after the area code
		// the delimiters between the other two components must match
		return !m[3].matched && m[4].str() == m[6].str();
}