[学习笔记]C++17学习第5天

mdl2999_52pj

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

int main()
{
    // 运算优先级 略
    // 位运算
    unsigned short number {16387};
    auto result { static_cast<unsigned short>(number << 2)} ;

    cout << "number = " << number << " number << 2 = " << result << endl;

    number = 16387;

    cout << "number = " << number ;

    number >>= 2;
    cout << " number >> 2 = " << number << endl; 

    number = 16387;
    cout << "number << 2 = " << (number<<2) << endl; 
}

mdl2999_52pj

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

int main()
{
    //位运算

    // 字体
    //  00000110      0       1      0     01100
    //  样式＝6    未使用    斜体  非粗体  点数＝12 
    unsigned short font {0b00'000'110'0'10'01100};  //
    unsigned short size_mask {0b11111};
    unsigned short style_mask {0xff00};

    auto size { static_cast<unsigned short>( font & size_mask ) };
    auto style{ static_cast<unsigned short>( (font & style_mask)>>8 ) };

    cout << "font size = " << size << endl;
    cout << "font style = " << style << endl;

    auto bold {static_cast<unsigned short>(1U<<5)};  // 粗体 
    auto italic {static_cast<unsigned short>(1U<<6)}; // 斜体

    cout << "font bold = " << (font & bold) << endl;
    cout << "font italic = " << (font & italic) << endl;  

    // 设置粗体
    font |= bold;
    // 清楚斜体
    font &= ~italic;
    cout << "font bold = " << (font & bold) << endl;
    cout << "font italic = " << (font & italic) << endl;

}

nanaqilin

楼主今天这段代码还是比简单的，楼主加油

mdl2999_52pj

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

int main()
{
    //枚举类型
    enum class Day {Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday};
    Day yesterday {Day::Monday}, today {Day::Tuesday}, tomorrow{Day::Wednesday};
    const Day poets_day {Day::Friday};

    enum class Punctuation : char {Comma=',', Exclamation='!', Question='?'};
    Punctuation  ch {Punctuation::Comma};

    cout << "Yesterday's value is " << static_cast<int>(yesterday)
        << static_cast<char>(ch) << " but poets day's is " << static_cast<int>(poets_day)
        << static_cast<char>(Punctuation::Exclamation) << endl;

    today = Day::Thursday;
    ch = Punctuation::Question;
    tomorrow = poets_day;

    cout << "Is today's value(" <<static_cast<int>(today) << ") the same as poets_day("
        <<static_cast<int>(poets_day) << ')' << static_cast<char>(ch) << endl;

    cout << static_cast<int>(tomorrow) << endl;
}

mdl2999_52pj

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

int main()
{

    // 练习题，提示输入两个整数，存储在a和b中，
    // 不使用第三个变量，交换两个数的值，并输出 

    cout << "Enter two integers:";
    int a,b;
    cin >> a >> b;
    cout << "a = " << a << " and b = " << b << endl;
    a = a^b;
    b = a^b;
    a = a^b;
    cout << "Now swap(a,b)\n";
    cout << "a = " << a << " and b = " << b << endl;
}

mdl2999_52pj

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

int main()
{
    char letter{};
    cout << "Enter a letter: ";
    cin >> letter;

    if (isupper(letter)) 
        cout << "You entered an uppercase letter.\n";
    else if (islower(letter)) 
        cout << "You entered a lowercase letter.\n";
    else
        cout << "You dit not enter a letter.\n";
}

croyance

唉 c++是最基础的，楼主加油啊