diff --git a/day6/d8.cpp b/day6/d8.cpp
new file mode 100644
index 0000000..28a7d8a
--- /dev/null
+++ b/day6/d8.cpp
@@ -0,0 +1,20 @@
+/*
+    0b 1100 0011 << 2   -67
+    0b 0000 1100        12
+
+    将二进制数向左（高位）移动，低位补0.  
+    [注意]左移是包含符号位的.
+*/
+#include <iostream>
+#include <bitset>
+
+using namespace std;
+
+int main()
+{
+    char n = 0b11000011;                                 // 0b 表示二进制表示法 0b11000011 = 195
+    cout << "n = " << bitset<8>(n) << endl;              // n = 11000011
+    n = n << 2;                                          // 建议不要使用 <<= 运算符，因为它会改变 n 的类型   // 0b00001100 = 12  195 << 2 = 12
+    cout << "n = " << bitset<8>(n) << "\t" << (int)n << endl; // n = 00001100
+    return 0;
+}
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