diff --git a/day5/d5.cpp b/day5/d5.cpp
new file mode 100644
index 0000000..7ca3386
--- /dev/null
+++ b/day5/d5.cpp
@@ -0,0 +1,25 @@
+// sizeof测试
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    char c = 'a';
+    cout << c << endl;
+    cout << sizeof(c) << endl;
+
+    short x = '1';
+    cout << x << endl;
+    cout << sizeof(x) << endl;
+
+    int z = 1;
+    cout << z << endl;
+    cout << sizeof(z) << endl;
+
+    bool y = true;
+    cout << y << endl;
+    cout << sizeof(y) << endl;
+
+    return 0;
+}
\ No newline at end of file