diff --git a/Lecture/lec_define.cpp b/Lecture/lec_define.cpp
new file mode 100644
index 0000000..568dd68
--- /dev/null
+++ b/Lecture/lec_define.cpp
@@ -0,0 +1,11 @@
+#include <iostream>
+using namespace std;
+
+#define PI 3.14159
+
+int main()
+{
+    cout << PI << endl;
+
+    return 0;
+}