错误：索引超出了c＃

Question

我正在尝试使用c＃接口概念编写小型程序用于circle＆amp;区域。 square.While给出具体条件if (args[0] == "S")时出现错误IndexOutOfRangeException：

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。你应该先检查长度：

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