added drill21 for chapter13

Author: trapperdot00

Chapter13/README.md

@@ -64,3 +64,6 @@ Modify the constructor to check that `age` is [0:150) and that `name` doesn't co
 
 ## [Drill 20](drill/20)
 Read a sequence of `Person`s from input (`cin`) into a `vector<Person>`; write them out again to the screen (`cout`). Test with correct and erroneous input.
+
+## [Drill 21](drill/21)
+Change the representation of `Person` to have `first_name` and `second_name` instead of `name`. Make it an error not to supply both a first and a second name. Be sure to fix `>>` and `<<` also. Test.

Chapter13/drill/21/Person.cpp

@@ -0,0 +1,18 @@
+#include "Person.h"
+
+std::istream& operator>>(std::istream& is, Person& rhs) {
+	std::string first_name;
+	std::string last_name;
+	int age = 0;
+	if (is >> first_name >> last_name >> age)
+		rhs = Person{first_name, last_name, age};
+	return is;
+}
+
+std::ostream& operator<<(std::ostream& os, const Person& rhs) {
+	return os << rhs.first_name()
+		<< ' '
+		<< rhs.last_name()
+		<< ' '
+		<< rhs.age();
+}

Chapter13/drill/21/Person.h

@@ -0,0 +1,35 @@
+#ifndef PERSON_H
+#define PERSON_H
+
+#include <string>
+#include <iostream>
+#include <stdexcept>
+
+class Person {
+public:
+	Person() {}
+	Person(const std::string& s1, const std::string& s2, int i)
+		: fn{s1}, ln{s2}, a{i}
+	{
+		static const std::string illegal{";:\"'[]*&^%$#@!"};
+		if (fn.find_first_of(illegal) != std::string::npos)
+			throw std::runtime_error{"first name contains invalid characters"};
+		if (ln.find_first_of(illegal) != std::string::npos)
+			throw std::runtime_error{"last name contains invalid characters"};
+		if (a < 0 || a > 149)
+			throw std::runtime_error{"invalid age"};
+	}
+
+	std::string first_name() const { return fn; }
+	std::string last_name() const { return ln; }
+	int age() const { return a; }
+private:
+	std::string fn;
+	std::string ln;
+	int a;
+};
+
+std::istream& operator>>(std::istream&, Person&);
+std::ostream& operator<<(std::ostream&, const Person&);
+
+#endif

Chapter13/drill/21/main.cpp

@@ -0,0 +1,16 @@
+#include "Person.h"
+
+#include <iostream>
+#include <vector>
+#include <utility>
+
+int main() {
+	std::vector<Person> persons;
+	std::cout << "Enter people:\n";
+	for (Person p; std::cin >> p; )
+		persons.push_back(std::move(p));
+
+	std::cout << "\nPeople:\n";
+	for (const Person& p : persons)
+		std::cout << p << '\n';
+}