diff --git a/day6/d3.cpp b/day6/d3.cpp
new file mode 100644
index 0000000..adfcb43
--- /dev/null
+++ b/day6/d3.cpp
@@ -0,0 +1,14 @@
+// 逻辑与短路
+#include <iostream>
+#include <bitset>
+
+using namespace std;
+
+int main()
+{
+    int a = 3, b = 4;
+    int c = (a<b) && (--a); // a自减1, a = a-1 => a = 2, c = 1
+    int d = (a>b) && (a++); // a++不会执行 => a = 2, d = 0
+    cout << a << "," << b << endl; // 2, 4
+    cout << c << "," << d << endl; // 1, 0
+}
diff --git a/day6/d4.cpp b/day6/d4.cpp
new file mode 100644
index 0000000..1968592
--- /dev/null
+++ b/day6/d4.cpp
@@ -0,0 +1,13 @@
+// 逻辑或短路
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    int a = 4, b = 2;
+    a += b;                        // a = 6
+    a = (a >= b) || b++;           // 6 >= 2 =>1 || b++ 右侧的b++不会执行
+    cout << a << "," << b << endl; // 1,2
+    return 0;
+}
\ No newline at end of file
diff --git a/day6/d5.cpp b/day6/d5.cpp
new file mode 100644
index 0000000..bea31c3
--- /dev/null
+++ b/day6/d5.cpp
@@ -0,0 +1,12 @@
+// 逻辑非测试
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    int a, b;
+    cin >> a >> b;                             // 3 4
+    cout << "!(a > b) = " << !(a > b) << endl; // !0 = 1
+    return 0;
+}
\ No newline at end of file