[学习笔记]C++17学习第2天

mdl2999_52pj

#  include  <iostream>
// c++17 c++20

using namespace std;

int main()
{
    //变量 是命名的内存段，只能存储相对应的数据
    // 基本数据类型 包含 整型、浮点型、字符型、布尔型等数值类型 

    //整型 
    int apple_count{52}; // 定义并初始化
    // 浮点型
    double pi {3.1415926}; 
    // 字符
    char ch = 'a';  
    // 布尔型
    bool flag(false);

    cout << apple_count << pi << ch << flag << endl;

}

mdl2999_52pj

#  include <iostream>
// c++17 

using namespace std;

int main()
{
    // 初始化
    int apple_count {15}; 
    int orange_count {}; // 初始化为0
    int total(apple_count + orange_count) ; //括号初始化
    double weight = 2.3; // 赋值号初始化;
    auto baskets = 10.0;  // 类型推断
    const int box {10}; // 固定值
    constexpr double pi { 3.1415926 }; // 固定值 

    cout << total << endl;
    cout << weight << endl;
    cout << baskets << endl; 
    cout << box  << endl;
    cout << pi << endl;
}

mdl2999_52pj

#  include <iostream>
// c++17
using namespace std;

int main()
{
    // 数值计算 
    long width{4};
    long length{5};
    long area{width*length};
    long perimeter{2*width + length * 2};

    cout << "area = " << area << ", perimeter = " << perimeter << endl;
}

mdl2999_52pj

#  include <iostream>
// c++ 17
using namespace std;

int main()
{
    int yards{}, feet{}, inches{};
    cout << "Enter a distance as yards, feet and inches "
        << "with the three values separated by spaces: " << endl;

    cin >> yards >> feet >> inches;

    constexpr int feet_per_yard {3};
    constexpr int inches_per_foot {12};

    int total_inches { inches + feet * inches_per_foot  + yards * feet_per_yard * inches_per_foot };
    cout << "The distances corresponds to " << total_inches << " inches." << endl;

    cout << "Enter a distance in inches: ";   
    cin >> total_inches ;

    inches = total_inches % inches_per_foot;    
    feet = total_inches / inches_per_foot;
    yards = feet / feet_per_yard;
    feet = feet % feet_per_yard;

    cout << "The distance corresponds to " << yards << " yards, " << feet << " feet, " << inches << " inches." << endl;

}

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