c# - Fizz buzz 程序奇怪的输出？

Question

为什么这会导致 1 2 Fizz 3 ？它不应该导致 1 2 Fizz 吗？!我对这个循环的输出有点困惑..？添加 else if 可以解决这个问题，我的问题是为什么？

for (int i = 1; i <= value; i++)
{
    if (i % 3 == 0)
    {
        ViewBag.Output += "Fizz ";
    }
    if (i % 5 == 0)
    {
        ViewBag.Output += "Buzz ";
    }
    else
    {
        ViewBag.Output += i.ToString() + " ";
    }
}

Answer 1

如果第一个 if 匹配，您不会跳过迭代。因此，当当前 i 未被 5 除时，您有 else 部分 i % 5 if block 评估:

    for (int i = 1; i <= value; i++)
    {
        if (i % 3 == 0)            
            ViewBag.Output += "Fizz ";             

        if (i % 5 == 0)            
            ViewBag.Output += "Buzz ";

        if ((i % 3 != 0) && (i % 5 != 0))
            ViewBag.Output += i.ToString() + " ";            
    }

使用您现在拥有的通用 else block 的替代解决方案:

    for (int i = 1; i <= value; i++)
    {
        if (i % 3 == 0)
        {          
            ViewBag.Output += "Fizz ";

            if (i % 5 == 0)
                ViewBag.Output += "Buzz ";             
        }
        else if (i % 5 == 0)
        {
            ViewBag.Output += "Buzz "
        }
        else // neither divided by 3 nor by 5
        {
           ViewBag.Output += i.ToString() + " ";
        }
    }

还有一个使用字典的解决方案，以避免所有这些额外的 if...else 检查:

var valuesToCheck = new Dictionary<int, string> {
    { 3, "Fizz" },
    { 5, "Buzz" }
};

for (int i = 1; i <= value; i++)
{
     bool divisorFound = false;

     foreach(var kvp in valuesToCheck)
     {
         if (i % kvp.Key == 0)
         {
             divisorFound = true;
             ViewBag.Output += kvp.Value + " ";
         }
     }

     if (!divisorFound)
         ViewBag.Output += i + " ";
}