？

?是C++中一种可以替换if else的简易语句，例子如下：
int main()
{
int a;
a = 5 > 3 ? 10 : 12;
a > 11 ? a = 11 : a = a * a;
std::cout << a;
}

switch case

一种更为省事的条件筛选器，使用限制是必须控制变量。

#include <iostream>
using namespace std;
void showmenu()
{
	cout << "pls enter 1,2,3,4 or 5:\n"
		"1)alarm             2)report\n"
		"3)alibi             4)comfort\n"
		"5)quit\n";
}
int main() {
	int i;
	showmenu();
	cin >> i;
	while (i != 5)
	{
		switch (i)
		{
		case 1:cout << "\a\n"; break;
		case 2:cout << "report!\n"; break;
		case 3:cout << "The boss was not here\n"; break;
		case 4:cout << "comfort\n"; break;
		default:cout << "not a chance\n";
		}
		cin >> i;
	}

}

可以和枚举一起用

include

enum {red,orange,yellow,green,blue,violet,indigo};

int main() {

using namespace std;
cout << "Enter color code(0-6): ";
int code;
cin >> code;
while (code >= red && code <= indigo)
{
    switch (code)
    {
    case red: cout << "red!\n";
        break;
    case orange:cout << "orange!\n";
        break;
    case yellow: cout << "yellow!\n";
        break;
    case green:cout << "green!\n";
        break;
    case blue: cout << "blue!\n";
        break;
    case violet:cout << "violet!\n";
        break;
    case indigo:cout << "indigo!\n";
        break;
    }
    cout << "Enter color code(0-6): ";
    cin >> code;
}

}