diff --git a/day7/d1.cpp b/day7/d1.cpp
new file mode 100644
index 0000000..955dac6
--- /dev/null
+++ b/day7/d1.cpp
@@ -0,0 +1,14 @@
+// 测试单分支结构
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    cout << "请输入一个数: ";
+    int n;
+    cin >> n;
+    if (n % 2 == 0)
+        cout << n << "666" << endl;
+    return 0;
+}
\ No newline at end of file
diff --git a/day7/d10.cpp b/day7/d10.cpp
new file mode 100644
index 0000000..380acbf
--- /dev/null
+++ b/day7/d10.cpp
@@ -0,0 +1,20 @@
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    int i = 1, total1 = 0, total2 = 0;
+    for (; i <= 100; i++)
+    {
+        if (i % 2 == 0)
+            total1 += i;
+        else
+            total2 += i;
+    }
+
+    cout << "1~100的偶数和为: " << total1 << endl;
+    cout << "1~100的奇数和为: " << total2 << endl;
+
+    return 0;
+}
\ No newline at end of file
diff --git a/day7/d11.cpp b/day7/d11.cpp
new file mode 100644
index 0000000..648c3ec
--- /dev/null
+++ b/day7/d11.cpp
@@ -0,0 +1,17 @@
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    int i = 1, total = 0;
+    while (i <= 100)
+    {
+        if (i % 3 == 0)
+            total += i;
+        i++;
+    }
+
+    cout << "1~100的3的倍数和为: " << total << endl;
+    return 0;
+}
\ No newline at end of file
diff --git a/day7/d12.cpp b/day7/d12.cpp
new file mode 100644
index 0000000..9a7d3c0
--- /dev/null
+++ b/day7/d12.cpp
@@ -0,0 +1,21 @@
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    char human_readable[] = "BKMGT"; // 人类可读的单位: 字节、千字节、兆字节、吉字节、太字节
+    int n;
+    int i = 0;
+    cout << "请输入一个数：";
+    cin >> n;
+
+    while (n >= 1024) // 原理: 除以 1024 直到小于 1024
+    {
+        n /= 1024;
+        i++;
+    }
+
+    cout << n << human_readable[i] << endl;
+    return 0;
+}
\ No newline at end of file
diff --git a/day7/d13.cpp b/day7/d13.cpp
new file mode 100644
index 0000000..b625223
--- /dev/null
+++ b/day7/d13.cpp
@@ -0,0 +1,31 @@
+// 输入一个正整数，输出它的二进制表示
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    char arr[32] = "";
+    int len = 0;
+    int n;
+    cout << "请输入一个数：";
+    cin >> n;
+
+    // 逐位取出
+    while (n)
+    {
+        if (n & 1)
+            arr[len++] = '1';
+        else
+            arr[len++] = '0';
+        n >>= 1;
+    }
+
+    // 逆序输出
+    while (len)
+        cout << arr[--len];
+
+    cout << endl;
+
+    return 0;
+}
\ No newline at end of file
diff --git a/day7/d14.cpp b/day7/d14.cpp
new file mode 100644
index 0000000..ad6d3aa
--- /dev/null
+++ b/day7/d14.cpp
@@ -0,0 +1,25 @@
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    char arr[32] = "";
+    int len = 0;
+
+    int n;
+    cout << "请输入一个正整数: ";
+    cin >> n;
+
+    while (n)
+    {
+        arr[len++] = n % 2 + 48; //// 将数字0或1转成 字符'0'或'1'; 48是'0'的ASCII码值
+        n /= 2;
+    }
+
+    while (len)
+        cout << arr[--len];
+
+    cout << endl;
+    return 0;
+}
\ No newline at end of file
diff --git a/day7/d15.cpp b/day7/d15.cpp
new file mode 100644
index 0000000..6b21c37
--- /dev/null
+++ b/day7/d15.cpp
@@ -0,0 +1,22 @@
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    int n;
+    cout << "输入一个正整数: ";
+    cin >> n;
+
+    int isStartShow = 0;
+    for (int i = 31; i >= 0; i--)
+    {
+        if ((n >> i) & 1) // 从最高位开始判断: 如果为 0 则不显示
+            isStartShow = 1;
+        if (isStartShow)
+            cout << ((n >> i) & 1);
+    }
+    cout << endl;
+
+    return 0;
+}
\ No newline at end of file
diff --git a/day7/d16.cpp b/day7/d16.cpp
new file mode 100644
index 0000000..18d53ba
--- /dev/null
+++ b/day7/d16.cpp
@@ -0,0 +1,28 @@
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    string name, pwd; // 用户名和密码
+
+    int n = 3; // 剩余尝试次数
+    while (n--)
+    {
+        cout << "请输入用户名: ";
+        cin >> name;
+        cout << "请输入密码: ";
+        cin >> pwd;
+        if (name == "fly" && pwd == "123")
+        {
+            cout << "登录成功" << endl;
+            break;
+        }
+        else if (n == 0)
+            break;
+        else
+            cout << "用户名或密码错误, 你还有" << n << "次机会" << endl;
+    }
+
+    return 0;
+}
\ No newline at end of file
diff --git a/day7/d17.cpp b/day7/d17.cpp
new file mode 100644
index 0000000..a16bf7f
--- /dev/null
+++ b/day7/d17.cpp
@@ -0,0 +1,28 @@
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    int total = 0;
+
+    // 实现方法 1
+    int i = 100;
+    while (i--)
+    {
+        if (i % 5 == 0)
+            continue;
+        total += i;
+    }
+
+    // 实现方法 2
+    // for (int i = 1; i < 100; i++)
+    // {
+    //     if (i % 5 == 0)
+    //         continue;
+    //     total += i;
+    // }
+
+    cout << "100以内除了5的倍数之外的数之和为: " << total << endl;
+    return 0;
+}
\ No newline at end of file
diff --git a/day7/d18.cpp b/day7/d18.cpp
new file mode 100644
index 0000000..9ef91f4
--- /dev/null
+++ b/day7/d18.cpp
@@ -0,0 +1,37 @@
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    int total = 0;
+
+    // goto 语句的使用
+    // 实现方法 1
+    //     int i = 100;
+    // flag:
+    //     while (i--)
+    //     {
+    //         if (i % 5 == 0)
+    //             goto flag;
+    //         total += i;
+    //     }
+
+    // 实现方法 2
+    int i = 0;
+abc:
+    if (i == 100)
+        goto show;
+
+    i++;
+    if (i % 5 == 0)
+        goto abc;
+
+    total += i;
+    if (i < 100)
+        goto abc;
+
+show:
+    cout << "100以内除了5的倍数之外的数之和为: " << total << endl;
+    return 0;
+}
\ No newline at end of file
diff --git a/day7/d2.cpp b/day7/d2.cpp
new file mode 100644
index 0000000..42eab32
--- /dev/null
+++ b/day7/d2.cpp
@@ -0,0 +1,16 @@
+// 测试双分支结构
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    cout << "请输入一个数: ";
+    int n;
+    cin >> n;
+    if (n % 2 == 0)
+        cout << n << "是偶数" << endl;
+    else
+        cout << n << "是奇数" << endl;
+    return 0;
+}
\ No newline at end of file
diff --git a/day7/d3.cpp b/day7/d3.cpp
new file mode 100644
index 0000000..8c8ea60
--- /dev/null
+++ b/day7/d3.cpp
@@ -0,0 +1,21 @@
+// 测试多分支结构
+#include <iostream>
+#include <cmath> // c++ 数学库: 提供 abs() 函数
+
+using namespace std;
+
+int main()
+{
+    cout << "请输入2个数: ";
+    int a, b;
+    cin >> a >> b;
+
+    if (a >= 0 && b >= 0)
+        cout << "a + b = " << a + b << endl;
+    else if (a < 0 && b < 0)
+        cout << "a * b = " << a * b << endl;
+    else
+    {
+        cout << "a 和 b 差值: " << abs(a - b) << endl;
+    }
+}
\ No newline at end of file
diff --git a/day7/d4.cpp b/day7/d4.cpp
new file mode 100644
index 0000000..3a590f1
--- /dev/null
+++ b/day7/d4.cpp
@@ -0,0 +1,26 @@
+// 嵌套分支
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    int n;
+    cout << "请输入一个整数: ";
+    cout << "请输入一个整数: ";
+    cin >> n;
+
+    if (n % 3 == 0 || n % 5 == 0)
+    {
+        // n 能被 3 或 5 整除
+        if (n % 3 == 0)
+            cout << "Fizz";
+        if (n % 5 == 0)
+            cout << "Buzz";
+        cout << endl;
+    }
+    else
+        cout << n << endl;
+
+    return 0;
+}
\ No newline at end of file
diff --git a/day7/d5.cpp b/day7/d5.cpp
new file mode 100644
index 0000000..a35a307
--- /dev/null
+++ b/day7/d5.cpp
@@ -0,0 +1,48 @@
+// 测试switch分支
+#include <iostream>
+#include <cmath>
+
+using namespace std;
+
+int main(int argc, char const *argv[])
+{
+    int n;
+    cout << "输入您的成绩:" << endl;
+    cin >> n;
+
+    switch (n)
+    {
+    case 100:
+        cout << "你是最优秀的 ";
+    case 99:
+    case 98:
+    case 97:
+    case 96:
+    case 95:
+    case 94:
+    case 93:
+    case 92:
+    case 91:
+    case 90:
+        cout << "A";
+        break;
+
+    case 89:
+    case 88:
+    case 87:
+    case 86:
+    case 85:
+    case 84:
+    case 83:
+    case 82:
+    case 81:
+    case 80:
+        cout << "B";
+        break;
+    default:
+        cout << "D";
+        break;
+    }
+    cout << endl;
+    return 0;
+}
\ No newline at end of file
diff --git a/day7/d6.cpp b/day7/d6.cpp
new file mode 100644
index 0000000..aada8e3
--- /dev/null
+++ b/day7/d6.cpp
@@ -0,0 +1,30 @@
+// 输入0，1，2三个数值，分别代表玩家的角色，0代表`亚索`、1代表`盲僧`、2代表`提莫`，输出“您选择的角色为 xxx”。
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    short n;
+    cout << "请选择角色: 0-亚索, 1-盲僧, 2-提莫";
+    cin >> n;
+    cout << "您选择的角色为: ";
+    switch (n)
+    {
+
+    default:
+        cout << "选择错误";
+        break;
+    case 0:
+        cout << "亚索";
+        break;
+    case 1:
+        cout << "盲僧";
+        break;
+    case 2:
+        cout << "提莫";
+        break;
+    }
+    cout << endl;
+    return 0;
+}
\ No newline at end of file
diff --git a/day7/d7.cpp b/day7/d7.cpp
new file mode 100644
index 0000000..e4f139c
--- /dev/null
+++ b/day7/d7.cpp
@@ -0,0 +1,24 @@
+// for循环测试: 使用位运算符实现以下条件：判断一个数的二进制表示中有多少个 1
+#include <iostream>
+#include <cmath>
+
+using namespace std;
+
+int main()
+{
+    int n = 0;
+    cout << "请输入一个整数: ";
+    cin >> n;
+
+    int count = 0; // 统计 1 的个数
+    int temp = 0;  // 临时变量
+    for (int i = 0; temp < n; i++)
+    {
+        temp = 1 << i;
+        if ((n & temp) == temp)
+            count++;
+    }
+
+    cout << n << " 的二进制表示中有 " << count << " 个 1" << endl;
+    return 0;
+}
\ No newline at end of file
diff --git a/day7/d8.cpp b/day7/d8.cpp
new file mode 100644
index 0000000..2018b85
--- /dev/null
+++ b/day7/d8.cpp
@@ -0,0 +1,21 @@
+// 输入一个数，输出小于这个数所有偶数
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    int n;
+    cout << "请输入一个数：";
+    cin >> n;
+    int i = 0;
+    while (i < n)
+    {
+        if (i % 2 == 0)
+            cout << i << "\t";
+        i++;
+    }
+    cout << endl;
+
+    return 0;
+}
\ No newline at end of file
diff --git a/day7/d9.cpp b/day7/d9.cpp
new file mode 100644
index 0000000..9b495f5
--- /dev/null
+++ b/day7/d9.cpp
@@ -0,0 +1,13 @@
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    int i = 1, total = 0;
+    for (; i <= 100; i++)
+        total += i;
+
+    cout << "1~100的和为: " << total << endl;
+    return 0;
+}
\ No newline at end of file