prepare for c++17

code/2/2.2.cpp

@@ -0,0 +1,34 @@
+//
+// 2.2.cpp
+// c++1x tutorial
+//
+// created by changkun at shiyanlou.com
+//
+// constexpr
+
+#include <iostream>
+#define LEN 10
+
+constexpr int len_foo() {
+    return 5;
+}
+
+constexpr int fibonacci(const int n) {
+    return n == 1 || n == 2 ? 1 : fibonacci(n-1)+fibonacci(n-2);
+}
+
+int main() {
+    char arr_1[10];
+    
+    char arr_2[LEN];
+    
+    const int len = 10;
+    char arr_3[len];
+    
+    char arr_5[len_foo()+5];
+    
+    std::cout << fibonacci(10) << std::endl;
+    // 1, 1, 2, 3, 5, 8, 13, 21, 34, 55
+    
+    return 0;
+}