Console.Writeline - 为什么缺少输出

Question

C#的绝对新手.试图运行这个程序,输出根本不会显示任何计算.为什么？我并不想通过P,Q,R,S为ADD,SUB,乘,除等,另外,我怎样才能把之间的"请输入数字"和用户名的空间？

string userName;
double  x, y;

Console.WriteLine(" Enter Your Name ");
userName = Console.ReadLine();
Console.WriteLine(" Please Enter A Number "+ userName);
First = Convert.ToDouble(Console.ReadLine());
Console.WriteLine("Please Enter Another Number"+ userName);
Second = Convert.ToDouble(Console.ReadLine());
Console.WriteLine("The addition of Two Numbers is",x,y, x*y);
Console.WriteLine("The substraction of Two Numbers is",x,y,x/y);
Console.WriteLine("The multiplication of Two Numbers is",x,y,x * y);
Console.WriteLine("The division of Two Numbers given is", x,y,x / y);
Console.ReadKey();

Answer 1

当你将其他参数传递到显示输出,你必须告诉WriteLine 哪里把它加入到占位符的格式线条,就像这样:

Console.WriteLine("The product of Two Numbers {0} and {1} is {2}", x, y, x*y);

职位从零开始.第一个附加参数(即x)的打印值将被替换{0}; 的值y将取代{1},和的值x*y将替代{2}在最终输出.

你不必这样做的原因userName是你传递了一个参数:

Console.WriteLine("Please Enter Another Number " + userName);

附加userName到"Please Enter Another Number"字符串的结果作为单个参数传递给WriteLine.您可以使用格式说明符重写它,如下所示:

Console.WriteLine("Please Enter Another Number {0}", userName);