diff --git a/extern/Makefile b/extern/Makefile
deleted file mode 100644
index 49ff7ba..0000000
--- a/extern/Makefile
+++ /dev/null
@@ -1,22 +0,0 @@
-CC = gcc
-CFLAGS = -Wall -MMD 
-LDFLAGS = -lm
-SRCS = $(wildcard *.c)
-OBJS = $(SRCS:.c=.o)
-DEPS = $(OBJS:.o=.d)
-TARGET = a.out
-
-all: $(TARGET)
-
-$(TARGET): $(OBJS)
-	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS) 
-
--include $(DEPS)
-
-%.o: %.c
-	$(CC) $(CFLAGS) -c $< -o $@ $(LDFLAGS)
-
-clean:
-	rm -f $(OBJS) $(DEPS) $(TARGET)
-
-
diff --git a/extern/p.c b/extern/p.c
deleted file mode 100644
index fce8568..0000000
--- a/extern/p.c
+++ /dev/null
@@ -1,12 +0,0 @@
-// gcc p.c q.c -lm でビルド
-// ./a.out で実行
-
-#include <stdio.h>
-#include "q.h"
-
-int main(){
-  float d = 1.23;
-  int id = q(d);
-  printf("floor(d) = %d\n", id);
-  return 0;
-}
diff --git a/extern/q.c b/extern/q.c
deleted file mode 100644
index 706d771..0000000
--- a/extern/q.c
+++ /dev/null
@@ -1,8 +0,0 @@
-#include <stdio.h>
-#include <math.h>
-
-int q(float x)
-{
-  printf("d = %f\n", x*2);
-  return floor(x*2); 
-}
diff --git a/extern/q.h b/extern/q.h
deleted file mode 100644
index 771b0f1..0000000
--- a/extern/q.h
+++ /dev/null
@@ -1,5 +0,0 @@
-// q.h
-
-extern int q(float);
-
-
diff --git a/extern_func/Makefile b/extern_func/Makefile
new file mode 100644
index 0000000..99385a7
--- /dev/null
+++ b/extern_func/Makefile
@@ -0,0 +1,31 @@
+CC = gcc
+CFLAGS = -Wall -MMD 
+LDFLAGS = -lm
+SRCS = $(wildcard *.c)
+OBJS = $(SRCS:.c=.o)
+DEPS = $(OBJS:.o=.d)
+PRES = $(OBJS:.o=.i)
+TARGET = a.out
+
+all: $(TARGET)
+
+$(TARGET): $(OBJS)
+	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS) 
+
+-include $(DEPS)
+
+%.o: %.c
+	$(CC) $(CFLAGS) -c $< -o $@ $(LDFLAGS)
+
+# プリプロセスのみ実行して .i ファイルを出力
+pre:
+	@for f in $(SRCS); do \
+		base=$$(basename $$f .c); \
+		$(CC) -E $(CFLAGS) $(DEFS) $(INCDIR) $$f $(LDFLAGS) -o $$base.i; \
+		echo "Preprocessed $$f -> $$base.i"; \
+	done
+
+clean:
+	rm -f $(OBJS) $(DEPS) $(TARGET) $(PRES)
+
+
diff --git a/extern_func/p.c b/extern_func/p.c
new file mode 100644
index 0000000..fce8568
--- /dev/null
+++ b/extern_func/p.c
@@ -0,0 +1,12 @@
+// gcc p.c q.c -lm でビルド
+// ./a.out で実行
+
+#include <stdio.h>
+#include "q.h"
+
+int main(){
+  float d = 1.23;
+  int id = q(d);
+  printf("floor(d) = %d\n", id);
+  return 0;
+}
diff --git a/extern_func/q.c b/extern_func/q.c
new file mode 100644
index 0000000..706d771
--- /dev/null
+++ b/extern_func/q.c
@@ -0,0 +1,8 @@
+#include <stdio.h>
+#include <math.h>
+
+int q(float x)
+{
+  printf("d = %f\n", x*2);
+  return floor(x*2); 
+}
diff --git a/extern_func/q.h b/extern_func/q.h
new file mode 100644
index 0000000..ae59f39
--- /dev/null
+++ b/extern_func/q.h
@@ -0,0 +1,6 @@
+// q.h
+
+extern int q(float);
+
+// int q(float); プロトタイプ宣言でも同じ
+
diff --git a/extern_variable/Makefile b/extern_variable/Makefile
new file mode 100644
index 0000000..99385a7
--- /dev/null
+++ b/extern_variable/Makefile
@@ -0,0 +1,31 @@
+CC = gcc
+CFLAGS = -Wall -MMD 
+LDFLAGS = -lm
+SRCS = $(wildcard *.c)
+OBJS = $(SRCS:.c=.o)
+DEPS = $(OBJS:.o=.d)
+PRES = $(OBJS:.o=.i)
+TARGET = a.out
+
+all: $(TARGET)
+
+$(TARGET): $(OBJS)
+	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS) 
+
+-include $(DEPS)
+
+%.o: %.c
+	$(CC) $(CFLAGS) -c $< -o $@ $(LDFLAGS)
+
+# プリプロセスのみ実行して .i ファイルを出力
+pre:
+	@for f in $(SRCS); do \
+		base=$$(basename $$f .c); \
+		$(CC) -E $(CFLAGS) $(DEFS) $(INCDIR) $$f $(LDFLAGS) -o $$base.i; \
+		echo "Preprocessed $$f -> $$base.i"; \
+	done
+
+clean:
+	rm -f $(OBJS) $(DEPS) $(TARGET) $(PRES)
+
+
diff --git a/extern_variable/data.c b/extern_variable/data.c
new file mode 100644
index 0000000..0377d2f
--- /dev/null
+++ b/extern_variable/data.c
@@ -0,0 +1,4 @@
+// data.c
+
+int shared_var = 173;
+
diff --git a/extern_variable/main.c b/extern_variable/main.c
new file mode 100644
index 0000000..510445e
--- /dev/null
+++ b/extern_variable/main.c
@@ -0,0 +1,9 @@
+// main.c
+#include <stdio.h>
+
+extern int shared_var;
+
+int main(void){
+  printf("shared_var = %d\n", shared_var);
+  return 0;
+}
diff --git a/static_variable/Makefile b/static_variable/Makefile
new file mode 100644
index 0000000..99385a7
--- /dev/null
+++ b/static_variable/Makefile
@@ -0,0 +1,31 @@
+CC = gcc
+CFLAGS = -Wall -MMD 
+LDFLAGS = -lm
+SRCS = $(wildcard *.c)
+OBJS = $(SRCS:.c=.o)
+DEPS = $(OBJS:.o=.d)
+PRES = $(OBJS:.o=.i)
+TARGET = a.out
+
+all: $(TARGET)
+
+$(TARGET): $(OBJS)
+	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS) 
+
+-include $(DEPS)
+
+%.o: %.c
+	$(CC) $(CFLAGS) -c $< -o $@ $(LDFLAGS)
+
+# プリプロセスのみ実行して .i ファイルを出力
+pre:
+	@for f in $(SRCS); do \
+		base=$$(basename $$f .c); \
+		$(CC) -E $(CFLAGS) $(DEFS) $(INCDIR) $$f $(LDFLAGS) -o $$base.i; \
+		echo "Preprocessed $$f -> $$base.i"; \
+	done
+
+clean:
+	rm -f $(OBJS) $(DEPS) $(TARGET) $(PRES)
+
+
diff --git a/static_variable/data.c b/static_variable/data.c
new file mode 100644
index 0000000..a4163a2
--- /dev/null
+++ b/static_variable/data.c
@@ -0,0 +1,8 @@
+// data.c
+
+static int internal_var = 876;
+
+int  get_internal_var(){
+  return internal_var;
+}
+
diff --git a/static_variable/main.c b/static_variable/main.c
new file mode 100644
index 0000000..1ced750
--- /dev/null
+++ b/static_variable/main.c
@@ -0,0 +1,12 @@
+// main.c
+#include <stdio.h>
+
+// extern int internal_var;
+extern int get_internal_var();
+
+int main(void){
+  // printf("internal_var = %d\n", internal_var);
+  printf("internal_var = %d\n", get_internal_var() );
+  return 0;
+}
+