int add = 4 + 2;

#include <iostream>

using namespace std;

int main()
{
    float operands, operated;
    /**
     * 设置为固定点表示法（fixed-point notation）浮点数会以固定的小数位数进行输出，不用科学计数法
     * 如果读者的编译器不接受 ios_base::fixed 也可以使用 ios::fixed
     */
    cout.setf(ios_base::fixed, ios_base::floatfield);
    cout << "输入一个数字：";
    cin >> operands;    //操作数
    cout << "输入另一个数字：";
    cin >> operated;    //被操作数

    cout << "operands  = " << operands << "; operated = " << operated << endl;  // 确认输入
    cout << "operands + operated = " << operands + operated << endl;            //加操作
    cout << "operands - operated = " << operands - operated << endl;            //减操作
    cout << "operands * operated = " << operands * operated << endl;            //乘操作
    cout << "operands / operated = " << operands / operated << endl;            //除操作
    return 0;
}

#include <iostream>
namespace MyNamespace
{
    int value = 42;
}

int main()
{
    std::cout << MyNamespace::value << std::endl;
    return 0;
}

#include <iostream>
int main()
{
    int num = 5;
    int result = num++;  // 先使用 num 的值 5 赋给 result，然后 num 再自增为 6
    std::cout << "result: " << result << ", num: " << num << std::endl;
    return 0;
}

#include <iostream>
int main()
{
    int num = 5;
    int result = ++num;  // 先将 num 自增为 6，然后再将 6 赋给 result
    std::cout << "result: " << result << ", num: " << num << std::endl;
    return 0;
}

#include <iostream>
int main()
{
    int a = 10;
    int b = 3;
    int result = a / b * 2;  // 先进行除法运算 10 / 3 = 3，再进行乘法运算 3 * 2 = 6
    std::cout << "result: " << result << std::endl;
    return 0;
}

#include <iostream>
int main()
{
    int a = 10;
    int b = 3;
    int result = a + b * 2;  // 先进行乘法运算 3 * 2 = 6，再进行加法运算 10 + 6 = 16
    std::cout << "result: " << result << std::endl;
    return 0;
}

#include <iostream>
int main()
{
    int a = 10;
    int b = 3;
    bool result = a > b;  // 比较 a 是否大于 b，结果为 true
    std::cout << "result: " << std::boolalpha << result << std::endl;
    return 0;
}

#include <iostream>
int main()
{
    int a = 10;
    int b = 3;
    bool result = a == b;  // 判断 a 是否等于 b，结果为 false
    std::cout << "result: " << std::boolalpha << result << std::endl;
    return 0;
}

#include <iostream>
int main()
{
    bool a = true;
    bool b = false;
    bool result = a && b;  // 逻辑与运算，结果为 false
    std::cout << "result: " << std::boolalpha << result << std::endl;
    return 0;
}

#include <iostream>
int main()
{
    bool a = true;
    bool b = false;
    bool result = a || b;  // 逻辑或运算，结果为 true
    std::cout << "result: " << std::boolalpha << result << std::endl;
    return 0;
}

#include <iostream>
int main()
{
    int a = 10;
    int b = 3;
    int result = (a > b) ? a : b;  // 如果 a 大于 b，则结果为 a，否则为 b
    std::cout << "result: " << result << std::endl;
    return 0;
}

#include <iostream>
int main()
{
    int a = 10;
    a += 5;  // 等价于 a = a + 5，将 a 的值更新为 15
    std::cout << "a: " << a << std::endl;
    return 0;
}

#include <iostream>
int main()
{
    int a = 10 - 3 - 2;  // 先计算 10 - 3 = 7，再计算 7 - 2 = 5
    std::cout << "a: " << a << std::endl;
    return 0;
}

#include <iostream>
int main()
{
    int a, b, c;
    a = b = c = 10;  // 先将 10 赋给 c，再将 c 的值赋给 b，最后将 b 的值赋给 a
    std::cout << "a: " << a << ", b: " << b << ", c: " << c << std::endl;
    return 0;
}

#include <iostream>
int main()
{
    double a = 7.0;
    double b = 2.0;
    double result = a / b;
    std::cout << "浮点数除法结果: " << result << std::endl;
    return 0;
}

#include <iostream>
int main()
{
    int a = 7;
    double b = 2.0;
    double result = a / b;
    std::cout << "混合类型除法结果: " << result << std::endl;
    return 0;
}

#include <iostream>
int main()
{
    int a = 7;
    int b = 0;
    // 以下代码会导致未定义行为，不要这样做
    // int result = a / b;
    // std::cout << result << std::endl;

    double c = 7.0;
    double d = 0.0;
    double result2 = c / d;
    std::cout << "浮点数除以零结果: " << result2 << std::endl;
    return 0;
}

#include <iostream>

using namespace std;

int main()
{
    // 定义总厘米长度
    int totalCentimeters = 235;

    // 使用整数除法计算米数
    int meters = totalCentimeters / 100;

    // 使用求模操作符计算剩余的厘米数
    int remainingCentimeters = totalCentimeters % 100;

    // 输出转换结果
    cout << totalCentimeters << " 厘米等于 " << meters << " 米 " << remainingCentimeters << " 厘米" << endl;

    return 0;
}

// 1. 基本算术运算练习
int a = 15, b = 4;
// 计算并输出：a+b, a-b, a*b, a/b, a%b

// 2. 优先级验证
int result1 = 3 + 4 * 5;     // 验证乘法优先级高于加法
int result2 = (3 + 4) * 5;  // 验证括号改变优先级

// 3. 混合类型运算
int x = 7;
double y = 2.5;
// 尝试各种组合，观察类型转换规则

// 4. 求模应用扩展
// 将秒数转换为小时、分钟、秒格式
int totalSeconds = 3665;
// 使用除法和求模进行转换