优化条件 [英] Optimize Conditions

问题描述

我有一个关于if和for或while循环中条件的简单问题. 有什么方法可以让我用更少的代码行来验证这种情况?

I've a simple question about conditions in if, and for or while loops. Is there any way that allows me to verify this condition with fewer lines of code?

if (are_you_sure != "Si" && are_you_sure != "si"
 && are_you_sure != "No" && are_you_sure != "no")

我认为我无法最小化上面的代码，但是我想确定.

I don't think i can minimize the code above, but I would like to be sure.

******编辑******

******EDIT******

感谢您的回答！ 我将下面的代码最小化了上面的代码:

Thanks for the answers! I minimized the code above with the code below:

int main()
{
    string choice;
    string list[4] = {"No", "no", "Yes", "yes"};

    cin >> choice;

    for (int i = 0; i < 4; ++i)
    {
        if (choice == list[i])
        {
            cout << "Is Here!";
            break;
        }
        else
        {
            cout << "\nNot found";
            cout << "\n" << i;
        }
    }
}

它可以帮助我了解其工作原理.

It helps me to understand how it works.

推荐答案

如果您有可以帮助您做到这一点的函数，则可以编写更少的代码，并使代码更具可读性:

You can write a lot less code, and make it more readable, if you have a function that does that for you:

if (none_of( are_you_sure, "Si", "si", "No", "no"))
  // ...

当然，必须编写该函数，但是使用c ++ 17 fold-expressions并不需要太多代码:

Of course, that function has to be written, but it's not too much code with c++17 fold-expressions:

template<typename T, typename ...Opts>
auto none_of(T val, Opts ...opts)
{
    return (... && (val != opts));
}  

这具有一些不错的属性；它可以接受任意数量的参数，并且还可以用于字符串以外的其他类型:

This has some nice properties; it can take any number of arguments, and also be used with types other than strings:

int n = 42;
if (none_of( n, 1, 2, 3))
  // ...

请确保对函数命名正确，因为这会大大影响可读性.

Make sure to name the function well, as that affects readability a lot.

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