c# - 有关在C#中执行while循环的问题

Question

所以我有此代码，您可以在其中输入“区域代码”，然后输入您希望通话多长时间。基本上，这是一个简单的计算器，它会根据您的区号确定 call 的费用。如果输入无效的区号，我很难弄清楚如何保持循环运行。到目前为止，如果我输入了无效的区号，则整个程序将仅在命令提示符下结束。这是代码:

using System;
using static System.Console;

namespace Chapter6._1
{
    class Program
    {
        static void Main()
        {
            // array info //
            int[] phoneAreacode = { 608, 414, 262, 815, 715, 920 };
            double[] phoneCost = { .05, .10, .07, .24, .16, .14 };
            // declaring variables //
            int x;
            int areaCode;
            double cost = 0;
            int callLength;
            bool validAreacode = false;
            // start of actual code //
            Write("Enter in the area code you want to call: ");
            areaCode = Convert.ToInt32(ReadLine());
            x = 0;
            while (x < phoneAreacode.Length && areaCode != phoneAreacode[x])
                ++x;
            if(x != phoneAreacode.Length)
            {
                validAreacode = true;
                cost = phoneCost[x];
            }
            if (validAreacode)
            {
                Write("Enter in the length of your call: ");
                callLength = Convert.ToInt32(ReadLine());
                double finalCost = callLength * cost;
                WriteLine("Your call to area code " + areaCode + " for " + callLength + " minutes will cost " + finalCost.ToString("C"));
            }
            else
            {
                WriteLine("YOU MUST ENTER A VALID AREA CODE!");
            }
        }
    }
}

Answer 1

您可以在此处执行do-While:

基本上，当您执行do-while时，您将强制完成do上的代码，直到while中的条件完成为止。在您的情况下，您需要在do语句中添加对pohne编号的检查，并且要知道此人是否选择了正确的值，可以执行Array.FindIndex():
这将是您的do-while循环，同时我也更改了x的index尝试将名称用于具有某些含义的变量。 (索引还是不完美)

do
{
    Write("Enter in the area code you want to call: ");
    areaCode = Convert.ToInt32(ReadLine());

    index = Array.FindIndex(phoneAreacode, w => w == areaCode);
    if (index >= 0)
    {
        validAreacode = true;
    }
    else
    {
        WriteLine("YOU MUST ENTER A VALID AREA CODE!");
    }

} while (!validAreacode);

这将是您的整个主要方法:

int[] phoneAreacode = { 608, 414, 262, 815, 715, 920 };
double[] phoneCost = { .05, .10, .07, .24, .16, .14 };
// declaring variables //
int index;
int areaCode;
int callLength;
bool validAreacode = false;
// start of actual code //



do
{
    Write("Enter in the area code you want to call: ");
    areaCode = Convert.ToInt32(ReadLine());

    index = Array.FindIndex(phoneAreacode, w => w == areaCode);
    if (index >= 0)
    {
        validAreacode = true;
    }
    else
    {
        WriteLine("YOU MUST ENTER A VALID AREA CODE!");
    }

} while (!validAreacode);


Write("Enter in the length of your call: ");
callLength = Convert.ToInt32(ReadLine());
double finalCost = callLength * phoneCost[index];
WriteLine("Your call to area code " + areaCode + " for " + callLength + " minutes will cost " + finalCost.ToString("C"));

如您所见，您还可以删除必须循环数组的 while和有效代码的 if-else。假设当代码到达目标点时，该区域是正确的。

尝试删除 if-else的数量是一个好习惯。