see #2: code updates

code/2/2.01.nullptr.cpp

@@ -4,6 +4,7 @@
 // modern cpp tutorial
 //
 // created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
 //
 
 #include <iostream>

code/2/2.02.constexpr.cpp

@@ -4,6 +4,7 @@
 // modern cpp tutorial
 //
 // created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
 //
 
 #include <iostream>

code/2/2.03.if.switch.cpp

@@ -4,6 +4,7 @@
 // modern cpp tutorial
 //
 // created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
 //
 
 #include <iostream>
@@ -13,13 +14,12 @@
 int main() {
     std::vector<int> vec = {1, 2, 3, 4};
 
-    // before c++17, can be simplefied by using `auto`
+    // after c++17, can be simplefied by using `auto`
     const std::vector<int>::iterator itr = std::find(vec.begin(), vec.end(), 2);
     if (itr != vec.end()) {
         *itr = 3;
     }
 
-    // after c++17, can be simplefied by using `auto`
     if (const std::vector<int>::iterator itr = std::find(vec.begin(), vec.end(), 3);
         itr != vec.end()) {
         *itr = 4;

code/2/2.04.initializer.list.cpp

@@ -4,6 +4,7 @@
 // modern cpp tutorial
 //
 // created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
 //
 
 #include <iostream>

code/2/2.05.structured.binding.cpp

@@ -4,6 +4,7 @@
 // modern cpp tutorial
 //
 // created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
 //
 
 #include <iostream>

code/2/2.06.auto.cpp

@@ -4,6 +4,7 @@
 // modern cpp tutorial
 //
 // created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
 //
 
 #include <initializer_list>

code/2/2.07.decltype.cpp

@@ -4,6 +4,7 @@
 // modern cpp tutorial
 //
 // created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
 //
 
 #include <iostream>

code/2/2.08.tail.return.type.cpp

@@ -4,6 +4,7 @@
 // modern cpp tutorial
 //
 // created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
 //
 
 #include <iostream>

code/2/2.09.decltype.auto.cpp

@@ -4,6 +4,7 @@
 // modern cpp tutorial
 //
 // created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
 //
 
 template<int i>

code/2/2.10.if.constexpr.cpp

@@ -4,6 +4,7 @@
 // modern cpp tutorial
 //
 // created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
 //
 
 #include <iostream>

code/2/2.11.for.loop.cpp

@@ -4,6 +4,7 @@
 // modern cpp tutorial
 //
 // created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
 //
 
 #include <iostream>

code/2/2.12.external.template.cpp

@@ -4,6 +4,7 @@
 // modern cpp tutorial
 //
 // created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
 //
 
 #include <iostream>

code/2/2.13.alias.template.cpp

@@ -4,6 +4,7 @@
 // modern cpp tutorial
 //
 // created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
 //
 
 #include <iostream>

code/2/2.14.default.template.param.cpp

@@ -4,6 +4,7 @@
 // modern cpp tutorial
 //
 // created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
 //
 
 #include <iostream>

code/2/2.15.variadic.template.param.cpp

@@ -4,6 +4,7 @@
 // modern cpp tutorial
 //
 // created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
 //
 
 #include <iostream>

code/2/2.16.fold.expression.cpp

@@ -4,6 +4,7 @@
 // modern cpp tutorial
 //
 // created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
 //
 
 #include <iostream>

code/2/2.18.non.type.template.auto.cpp

@@ -4,6 +4,7 @@
 // modern cpp tutorial
 //
 // created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
 //
 
 #include <iostream>

code/2/Makefile

@@ -1,3 +1,10 @@
+#
+# modern cpp tutorial
+#
+# created by changkun at changkun.de
+# https://github.com/changkun/modern-cpp-tutorial
+#
+
 all: $(patsubst %.cpp, %.out, $(wildcard *.cpp))
 
 %.out: %.cpp Makefile

code/2/todo/2.7.cpp

@@ -3,6 +3,7 @@
 // modern c++ tutorial
 //
 // created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
 //
 // 面向对象增强
 

code/2/todo/2.8.cpp

@@ -3,6 +3,7 @@
 // modern c++ tutorial
 //
 // created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
 //
 // 强类型枚举