finished 17.3.1.

ch17/README.md

@@ -90,4 +90,22 @@ Because `std::accumulate`'s third parameter is the initial value of the sum. It'
 
 > Write an integral object that contains the correct answers for the true/false quiz. Use it to generate grades on the quiz for the data structure from the previous two exercises.
 
-[Test `QuizResponses` class](ex17_11_quiz_responses_test.cpp)
+[Test `QuizResponses` class](ex17_11_quiz_responses_test.cpp)
+
+## Exercise 17.14
+
+> Write several regular expressions designed to trigger various errors. Run your program to see what output your compiler generates for each error.
+
+[Try error code 1](ex17_14.cpp)
+
+## Exercise 17.15
+
+> Write a program using the pattern that finds words that violate the “i before e except after c” rule. Have your program prompt the user to supply a word and indicate whether the word is okay or not. Test your program with words that do and do not violate the rule.
+
+[I before E except after C rule](ex17_15.cpp)
+
+## Exercise 17.16
+
+> What would happen if your regex object in the previous program were initialized with "[^c]ei"? Test your program using that pattern to see whether your expectations were correct.
+
+`[^c]ei` says we want any such letter that is followed by the letters 'ei', This pattern describes strings containing exactly **three** characters. The test words in [ex17_15](ex17_15.cpp) will all fail.

ch17/ex17_14.cpp

@@ -0,0 +1,20 @@
+#include <exception>
+#include <iostream>
+#include <regex>
+#include <string>
+
+using std::regex;
+
+int main()
+{
+    try {
+        regex r("[[:alnum]+\\.(cpp|cxx|cc)$", regex::icase);
+    }
+    catch (std::regex_error e) {
+        std::cout << e.what() << "\ncode:" << e.code() << std::endl;
+    }
+}
+
+// output
+// Unexpected end of character class.
+// code:1

ch17/ex17_15.cpp

@@ -0,0 +1,38 @@
+#include <exception>
+#include <iostream>
+#include <regex>
+#include <string>
+
+using std::regex;
+
+//! @check https://en.wikipedia.org/wiki/I_before_E_except_after_C
+int main()
+{
+    try {
+        regex r("[[:alpha:]]*(cie|[^c]ei)[[:alpha:]]*");
+        std::string word;
+        while (std::cout << "Enter a word, or q to quit: ", std::cin >> word) {
+            if (word == "q") break;
+            std::smatch result;
+            if (std::regex_search(word, result, r))
+                std::cout << "Violate the rule: 'i before e except after c'"
+                          << std::endl;
+            else
+                std::cout << word + " is okay." << std::endl;
+        }
+    }
+    catch (std::regex_error e) {
+        std::cout << e.what() << "\ncode:" << e.code() << std::endl;
+    }
+}
+
+//! @test
+// Enter a word, or q to quit: believe
+// believe is okay.
+// Enter a word, or q to quit: receive
+// receive is okay.
+// Enter a word, or q to quit: species
+// Violate the rule: 'i before e except after c'
+// Enter a word, or q to quit: seize
+// Violate the rule: 'i before e except after c'
+// Enter a word, or q to quit: q