Revert "fix bug"

This reverts commit bff10a6.

ch11/ex11_3_4.cpp

@@ -15,6 +15,19 @@
 #include <cctype>
 #include <algorithm>
 
+void remove_punct(std::string &s)
+{
+    auto iter = s.begin();
+    while(iter != s.end())
+    {
+        if(std::ispunct(*iter))
+        {
+            iter =  s.erase(iter);
+        }
+        else
+            ++ iter;
+    }
+}
 
 //! Exercise 11.4
 void word_count_pro(std::map<std::string, int> &m)
@@ -23,9 +36,7 @@ void word_count_pro(std::map<std::string, int> &m)
     while(std::cin >> word)
     {
         for(auto& ch : word)    ch = std::tolower(ch);
-        //! Erase-remove idiom
-        //! http://en.wikipedia.org/wiki/Erase-remove_idiom
-        word.erase(std::remove_if(word.begin(), word.end(), ispunct), word.end());
+        remove_punct(word);
         ++m[word];
 
         for (const auto &e : m)