if语句中的多个条件 [英] Multiple conditions in if statement

问题描述

无论这里生成什么数字，我总是得到第一个选项(企鹅).我的代码似乎看不到任何问题，其他人看到了什么问题吗?

No matter what number is generated here I always get the first option (penguins). I can't seem to see any problem with my code, anyone else see what's wrong?

{
    srand(time(0));
    prand = (rand() % 20);
    if (prand == 1,5,9,10,14,15,19,20){
        entity = "penguins";
        srand(time(0));
        pquantity = (rand() % 8) + 2;
    }
    else if (prand == 2,6,11,16,18){
        entity = "troll";
        pquantity = 1;
    }
    else if (prand == 3,7,12,17){
        entity = "goblin";
        pquantity = 1;
    }
    else if (prand == 4,8,13){
        entity = "wizard";
        pquantity = 1;
    }
}

推荐答案

代码片段 prand == 1,5,9,10,14,15,19,20 是表达式序列(，通常称为逗号运算符)，其中 first (或 last (取决于语言))仅将 表达式用作 if 语句的条件.对其余的表达式进行评估，并忘记它们的值(请注意，在更复杂的情况下，这可能会导致严重的副作用.)

The code fragment prand == 1,5,9,10,14,15,19,20 is a sequence of expressions (the , is usually know as the comma operator), where the result of the first (or last — depending on language) expression only is used as a condition for the if statement. The remaining expressions are evaluated and their value is forgotten (please note this may lead to serious side effects in more complex situations.)

尚不清楚您使用的是哪种语言，但是在C#中，您可以使用切换语句以实现所需的内容:

It's not very clear what language you are using, but in, say, C# you could use a switch statement to achieve what you want:

switch (prand)
{
    // first set of options
    case 1:
    case 5:
    …
    case 20:
        // your code here
        break;

    // second set of options
    case 2:
    case 6: 
    …
    case 18:
        // your code here
        break;

    default:
        // all other options not listed above
        break;
}

大多数语言都有这样的陈述.有关一般说明，请参见此维基百科文章.

Most languages have such a statement. See this wikipedia article for a general description.

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