Fixed an infinite loop bugs in 9_43_44.

1. reference: Mooophy/Cpp-Primer#206
2. gcc cannot support c++11 feature(cann't return iterator from
string::insert)

ch09/ex9_43.cpp

@@ -9,29 +9,31 @@
 //          Using iterators, and the insert and erase functions replace
 //          all instances of oldVal that appear in s by newVal.
 //          Test your function by using it to replace common abbreviations,
-//          such as “tho” by “though” and “thru” by “through”.
+//          such as "tho" by "though" and "thru" by "through".
+//  @Compile    Gcc can't support return iterator of string::insert. Please use clang or VS2013
 
 #include <iostream>
 #include <string>
 
-using std::cout; using std::endl; using std::string;
+using std::cout; using std::endl; using std::string; using std::prev;
 
-void func(string &s, const string &oldVal, const string &newVal)
-{
-    for (string::size_type i=0; i!=s.size(); ++i)
-        if (s.substr(i, oldVal.size()) == oldVal)
-            {
-                s.erase(i, oldVal.size());
-                s.insert(i, newVal);
-            }
+void Replace(string &s, string const& oldVal, string const& newVal) {
+    auto val_size = oldVal.size();
+    if (s.size() < val_size) return;
+
+    for (auto iter = s.begin(), end = prev(s.end(), val_size - 1); iter != end; ++iter) {
+        if (string{iter, iter + val_size} == oldVal) {
+            iter = s.earse(iter, iter + val_size);
+            iter = s.insert(iter, newVal.cbegin(), newVal.cend()); // gcc 4.9 bug (see http://stackoverflow.com/questions/29690369)
+            iter += newVal.size();
+        }
+    }
 }
 
 int main()
 {
     string str{"To drive straight thru is a foolish, tho courageous act."};
-    func(str, "tho", "though");
-    func(str, "thru", "through");
+    Replace(str, "tho", "though");
+    Replace(str, "thru", "through");
     cout << str << endl;
-
-    return 0;
 }

ch09/ex9_44.cpp

@@ -11,21 +11,21 @@
 #include <iostream>
 #include <string>
 
-using std::cout; using std::endl; using std::string;
+using std::cout; using std::endl; using std::string; using std::prev;
 
-void func(string &s, const string &oldVal, const string &newVal)
+void Replace(string& s, string const& oldVal, string const& newVal)
 {
-    for (string::size_type i=0; i!=s.size(); ++i)
-        if (s.substr(i, oldVal.size()) == oldVal)
-            s.replace(i, oldVal.size(), newVal);
+    for ( string::size_type i = 0; i != s.size(); ++i )
+        if ( s.substr( i, oldVal.size() ) == oldVal ) {
+            s.replace( i, oldVal.size(), newVal );
+            i += newVal.size() - 1;
+        }
 }
 
 int main()
 {
     string str{"To drive straight thru is a foolish, tho courageous act."};
-    func(str, "tho", "though");
-    func(str, "thru", "through");
+    Replace( str, "tho", "though" );
+    Replace( str, "thru", "through" );
     cout << str << endl;
-
-    return 0;
 }