Using obj/ for .o files.

Makefile

@@ -9,17 +9,17 @@ MKDIR=mkdir -p
 RM=rm -rf
 
 SRC_FILES := $(wildcard src/*.c)
-OBJ_FILES := $(addprefix src/, $(notdir $(SRC_FILES:.c=.o)))
+OBJ_FILES := $(addprefix obj/, $(notdir $(SRC_FILES:.c=.o)))
 
 all: $(OBJ_FILES)
 	$(MKDIR) bin
-	$(CXX) $(CXXFLAGS) $(LIBS) -o bin/cointoss src/*.o
+	$(CXX) $(CXXFLAGS) $(LIBS) -o bin/cointoss obj/*.o
 
-src/%.o: src/%.c
+obj/%.o: src/%.c
 	$(CXX) $(CXXFLAGS) $(INCLUDES) -c -o $@ $<
 
 clean:
-	$(RM) src/*.o
+	$(RM) obj/*.o
 
 cleanall: clean
 	$(RM) bin

obj/readme.txt

@@ -0,0 +1 @@
+This is where the object output files go. This readme file is a simple hack so that git registers it (git doesn't register empty directories).