在C++中，可以使用if-else語句、switch語句或者函數指針等方法來處理多條件選擇。下面是每種方法的簡要說明和示例：

1. if-else語句：

#include <iostream>
using namespace std;

int main() {
    int condition1 = 10;
    int condition2 = 20;
    int condition3 = 30;

    if (condition1 < condition2 && condition1 < condition3) {
        cout << "Condition 1 is the smallest." << endl;
    } else if (condition2 < condition1 && condition2 < condition3) {
        cout << "Condition 2 is the smallest." << endl;
    } else {
        cout << "Condition 3 is the smallest." << endl;
    }

    return 0;
}

2. switch語句：

#include <iostream>
using namespace std;

int main() {
    int condition = 2;

    switch (condition) {
        case 1:
            cout << "Condition is 1." << endl;
            break;
        case 2:
            cout << "Condition is 2." << endl;
            break;
        case 3:
            cout << "Condition is 3." << endl;
            break;
        default:
            cout << "Invalid condition." << endl;
            break;
    }

    return 0;
}

3. 函數指針：

#include <iostream>
using namespace std;

void condition1() {
    cout << "Condition 1 is true." << endl;
}

void condition2() {
    cout << "Condition 2 is true." << endl;
}

void condition3() {
    cout << "Condition 3 is true." << endl;
}

int main() {
    int condition = 2;
    void (*condition_func[])() = {&condition1, &condition2, &condition3};

    if (condition >= 1 && condition <= 3) {
        condition_func[condition - 1]();
    } else {
        cout << "Invalid condition." << endl;
    }

    return 0;
}

這些方法可以根據具體需求選擇使用。if-else語句適用于簡單的條件判斷，switch語句適用于基于離散值的多個條件判斷，而函數指針則適用于更復雜的條件邏輯。