錯誤：指數是陣列的C＃中的邊界之外

Question

我使用C＃界面概念圓& square.While給予特定條件if (args[0] == "S")面積有錯誤IndexOutOfRangeException試圖寫小程序：

if (args[0]=="S") 
    fig = new Square(); 
if (args[0]=="C") 
    fig = new Circle(); 

Answer 1

如果args爲空，則會發生這種情況。你不能要求空數組的第一個元素，因爲沒有一個。您應該首先檢查長度：

if (args.Length == 0) 
{ 
    // Maybe exit? Is it valid not to specify any arguments? 
} 
// Either use an "else" here, or if you've quit in the "if" block 
// then you don't need to because you know that there's at least 
// one argument by now