book: translation of ch04

Update #12

code/4/Makefile

@@ -0,0 +1,14 @@
+#
+# 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
+	clang++ $< -o $@ -std=c++2a -pedantic
+
+clean:
+	rm *.out