错误：指数是阵列的C＃中的边界之外

Question

我使用C＃界面概念圆& square.While给予特定条件if (args[0] == "S")面积有错误IndexOutOfRangeException试图写小程序：

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

Answer 1

如果args为空，则会发生这种情况。你不能要求空数组的第一个元素，因为没有一个。您应该首先检查长度：

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