Question

我有一些代码可以检测QListWidget

中选择了哪个标签

int currentTab=ui->tabWidget->currentIndex();

if (currentTab==0)
     {
     // Code here
     }
else if (currentTab==1)
     {
    // Code here
     }
else if (currentTab==2)
     {
     // code here
     }
else if (currentTab==3)
     {
   // code here
     }

如何使用枚举代替if(currentTab==0)或if(currentTab==1)或if(currentTab==2)或if(currentTab==3)

Answer 1

我将按以下方式处理相同的事情（使用枚举类型）：

enum Tabs {
    Tab1,
    Tab2,
    Tab3
};

void foo()
{
    int currentTab = ui->tabWidget->currentIndex();
    switch (currentTab) {
    case Tab1:
        // Handle the case
        break;
    case Tab2:
        // Handle the case
        break;
    case Tab3:
        // Handle the case
        break;
    default:
        // Handle all the rest cases.
        break;
    }
}

Answer 2

使用下面给出的枚举的示例如果你想在两个枚举中使用相同的枚举元素，那么你可以使用enum classes (strongly typed enumerations) C++11。

#include <iostream>
#include <cstdint>

using namespace std;

//enumeration with type and size
enum class employee_tab : std::int8_t {
    first=0 /*default*/, second, third, last /*last tab*/
};

enum class employee_test : std::int16_t {
    first=10 /*start value*/, second, third, last /*last tab*/
};

enum class employee_name : char {
    first='F', middle='M', last='L'
};

int main(int argc, char** argv) {

    //int currentTab=ui->tabWidget->currentIndex();
    employee_tab currentTab = (employee_tab)1;
    switch (currentTab) {
        case employee_tab::first: //element with same name
            cout << "First tab Selected" << endl;
            break;
        case employee_tab::second:
            cout << "Second tab Selected" << endl;
            break;
        case employee_tab::third:
            cout << "Third tab Selected" << endl;
            break;
        case employee_tab::last: //element with same name
            cout << "Fourth tab Selected" << endl;
            break;
    }

    employee_name currentName = (employee_name)'F';
    switch (currentName) {
        case employee_name::first: //element with same name
            cout << "First Name Selected" << endl;
            break;
        case employee_name::middle:
            cout << "Middle Name Selected" << endl;
            break;
        case employee_name::last: //element with same name
            cout << "Last Name Selected" << endl;
            break;
    }

    return 0;
}

<强>输出：
第二个选项卡选择
选择名字

使用枚举而不是硬编码值

2 个答案: