diff --git a/1_Colleen/Makefile b/1_Colleen/Makefile
index 2e0a584..cb73354 100644
--- a/1_Colleen/Makefile
+++ b/1_Colleen/Makefile
@@ -61,7 +61,6 @@ else
   RM_OBJS     = rm -rf $(D_OBJS)
 endif
 
-
 # - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - #
 #             .   target: prerequisites   .   $@ : target             #
 #    RULES    .           recipe          .   $< : 1st prerequisite   #
@@ -93,6 +92,32 @@ $(NAME): $(OBJS)
 leaks: $(NAME)
 	valgrind --leak-check=full --show-leak-kinds=all ./$(NAME)
 
+#diff: $(NAME)
+#	@echo $(CYAN)"compare source with output :"$(RESET)
+#	@echo "diff --color --report-identical-files tmp_$(NAME) $(SRCS)"
+#	@diff_output=$$(diff --color --report-identical-files tmp_$(NAME) $(SRCS)); \
+#		diff_exit=$$?; \
+#		diff_color=$(RED); \
+#		if [ "$$diff_exit" -eq 0 ]; then diff_color=$(GREEN); fi; \
+#		echo $$diff_color"$$diff_output"$(RESET);
+
+# old diff version :
+#diff: $(NAME)
+#	@echo $(CYAN)"compare source with output :"$(RESET)
+#	./$(NAME) > tmp_$(NAME)
+#	- diff --color --report-identical-files tmp_$(NAME) $(SRCS)
+#	rm tmp_$(NAME)
+
+diff:
+	@echo $(CYAN)"compare source with output :"$(RESET)
+	- diff --color tmp_$(NAME) $(SRCS); \
+		if [  $$? -eq 0 ]; then echo $(GREEN)"Files $(NAME) and $(SRCS) are identical"$(RESET); fi
+
+#diff:
+#	@echo $(CYAN)"compare source with output :"$(RESET)
+#	$(shell diff --color tmp_$(NAME) $(SRCS) )
+#	@if [  $(.SHELLSTATUS) -eq 0 ]; then echo $(GREEN)"Files $(NAME) and $(SRCS) are identical"$(RESET); fi
+
 clean:
 	$(RM_OBJS)
 
diff --git a/1_Colleen/tmp_Colleen b/1_Colleen/tmp_Colleen
new file mode 100644
index 0000000..6bb97ab
--- /dev/null
+++ b/1_Colleen/tmp_Colleen
@@ -0,0 +1,14 @@
+/*comment outside*/
+#include <stdio.h>
+
+char *second_function() {
+	return "/*comment outside*/%c#include <stdio.h>%c%cchar *second_function() {%c	return %c%s%c;%c}%c%cint main() {%c	/*comment inside*/%c	char *program = second_function();%c	printf(program, 10, 10, 10, 10, 34, program, 34, 10, 10, 10, 10, 10, 10, 10, 10, 10);%c	return 0;%c}%c";
+}
+
+
+int main() {
+	/*comment inside*/
+	char *program = second_function();
+	printf(program, 10, 10, 10, 10, 34, program, 34, 10, 10, 10, 10, 10, 10, 10, 10, 10);
+	return 0;
+}