控制台应用程序c#循环

您的问题是您读入数据一次，然后继续循环而没有获得任何新数据。如果你移动

Console.Write("Please enter the diameter of your pizza (0 to end program): ");  // get user to input diameter
diameter = Convert.ToDouble(Console.ReadLine()); // read a line of text (string) from the keyboard,

内的循环，它应该解决你的问题

移动这两行:

Console.Write("Please enter the diameter of your pizza (0 to end program): ");  // get user to input diameter
            diameter = Convert.ToDouble(Console.ReadLine()); // read a line of text (string) from the keyboard,

内部的do/while循环。

你的代码变成:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace SOHelp
{
    class Program
    {
        static void Main(string[] args)
        {
              //DECLARATIONS
        double circleArea;  // area of pizza
        double diameter; // diameter of the pizza
        double areaOfSlice; // area of the slices
        double radius; // half the diameter of the pizza
        double slices = 0; // number of pizza slices
        string message = ""; // a string to hold a message to the user
        const int DIAMETER_RANGE_MASSIVE = 36;
        const int DIAMETER_RANGE_EXTRA_LARGE = 30;
        const int DIAMETER_RANGE_LARGE = 24;
        const int DIAMETER_RANGE_MED = 16;
        const int DIAMETER_RANGE_LOW = 12; // Low end on range scale for diameter
        const int SLICES_LOW_DIAMETER = 8; // number of pizza slices based on diameter
        const int SLICES_MID_DIAMETER = 12; // number of pizza slices based on diameter
        const int SLICES_HIGH_DIAMETER = 16; // number of pizza slices based on diameter
        const int SLICES_GIANT_DIAMETER = 24; // number of pizza slices based on diameter        
        bool needInput = true;
        const int END_PROGRAM = 0;


        // INPUT
        // Prompt for and get keyboard input

        // convert that string to an double,
        // assign the resulting value to diameter
        // PROCESSING
        // determine if diameter meets requirements of 12" to 36"
        // if does not meet requirements show error message and have user enter in new diameter
        string message = "Please enter the diameter of your pizza (0 to end program): ";
        do
        {
            Console.Write(message);  // get user to input diameter
            diameter = Convert.ToDouble(Console.ReadLine()); // read a line of text (string) from the keyboard,
            if (diameter < DIAMETER_RANGE_LOW || diameter > DIAMETER_RANGE_MASSIVE)
            {
                message = "'nENTRY ERROR";
                message += "'nPizza must have a diameter in the range of 12” to 36” inclusive!";
                message += "'nPlease try again.";
            }

        else {    
            needInput = false;
                // determine the number of slices based on diameter

                if (diameter >= DIAMETER_RANGE_LOW && diameter < DIAMETER_RANGE_MED)
                {
                    slices = (SLICES_LOW_DIAMETER);
                }
                else if (diameter < DIAMETER_RANGE_LARGE)
                {
                    slices = (SLICES_MID_DIAMETER);
                }
                else if (diameter < DIAMETER_RANGE_EXTRA_LARGE)
                {
                    slices = (SLICES_HIGH_DIAMETER);
                }
                else
                {
                    slices = (SLICES_GIANT_DIAMETER);
                }
                Console.Clear(); // clears console to show new output lines
                //OUTPUT
                for (int slicesAddFour = 8; slicesAddFour <=slices; slicesAddFour+=4) // for each slices
                {
                // determine the area of the slices
                radius = diameter / 2; // uses diameter to get radius
                circleArea = Math.PI * Math.Pow(radius, 2); // uses math class to calculate circle area  
                areaOfSlice = Math.Round((circleArea / slices), 2); // divides circle area by slices, takes the result of above calculation and rounds
                Console.WriteLine("'nA {0}'" Pizza diameter: {0}'".", diameter); 
                message +=("'n==============================================");
                Console.WriteLine("'nCut in {0} slices results in an area of {1}'" per slice.",areaOfSlice,slices);
                }

        } //end of else
            message = ("'nPlease enter the diameter of your pizza (0 to end program)");
            needInput = true;
        } while (diameter != END_PROGRAM && needInput);
    }
}
        }

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace Lab6B
{
    class Program
    {
        static void Main(string[] args)
        {
            //DECLARATIONS
            double circleArea;  // area of pizza
            double diameter; // diameter of the pizza
            double areaOfSlice; // area of the slices
            double radius; // half the diameter of the pizza
            double slices = 0; // number of pizza slices
            const int INPUT_MAX = 36; // maximum entry for diameter
            const int DIAMETER_RANGE_EXTRA_LARGE = 30; // diameter range used to figure out slices
            const int DIAMETER_RANGE_LARGE = 24; // diameter range used to figure out slices
            const int DIAMETER_RANGE_MED = 16; // diameter range used to figure out slices
            const int INPUT_MIN = 12; // minimum entry for diameter
            const int SLICES_LOW_DIAMETER = 8; // number of pizza slices based on diameter
            const int SLICES_MID_DIAMETER = 12; // number of pizza slices based on diameter
            const int SLICES_HIGH_DIAMETER = 16; // number of pizza slices based on diameter
            const int SLICES_GIANT_DIAMETER = 24; // number of pizza slices based on diameter        
            bool needInput = true; // does the program need input true or false
            const int END_PROGRAM = 0; // 0 ends the program


            // INPUT
            // Prompt for and get keyboard input
            Console.Write("Please enter the diameter of your pizza: ");  // get user to input diameter
            diameter = Convert.ToDouble(Console.ReadLine()); // read a line of text (string) from the keyboard, 
            // convert that string to an double,
            // assign the resulting value to diameter
            while (diameter != END_PROGRAM && needInput) // Begin while loop
            {
                // PROCESSING
                // determine if diameter meets requirements of 12" to 36"
                // if does not meet requirements show error message and have user enter in new diameter

                if (diameter < INPUT_MIN || diameter > INPUT_MAX)
                {
                    Console.WriteLine( "'nENTRY ERROR'nPizza must have a diameter in the range of 12” to 36” inclusive!'nPlease try again.");
                }

                else
                {
                    needInput = false;
                    // determine the number of slices based on diameter

                    if (diameter < DIAMETER_RANGE_MED)
                    {
                        slices = (SLICES_LOW_DIAMETER);
                    }
                    else if (diameter < DIAMETER_RANGE_LARGE)
                    {
                        slices = (SLICES_MID_DIAMETER);
                    }
                    else if (diameter < DIAMETER_RANGE_EXTRA_LARGE)
                    {
                        slices = (SLICES_HIGH_DIAMETER);
                    }
                    else
                    {
                        slices = (SLICES_GIANT_DIAMETER);
                    }
                    Console.Clear(); // clears console to show new output lines
                    //OUTPUT
                    Console.WriteLine("'nA {0}'" Pizza diameter: {0}'".", diameter);
                    Console.WriteLine("'n==============================================");
                    for (int slicesAddFour = 8; slicesAddFour <= slices; slicesAddFour += 4) // for each slices
                    {
                        // determine the area of the slices
                        radius = diameter / 2; // uses diameter to get radius
                        circleArea = Math.PI * Math.Pow(radius, 2); // uses math class to calculate circle area  
                        areaOfSlice = Math.Round((circleArea / slicesAddFour), 2); // divides circle area by slices, takes the result of above calculation and rounds

                        Console.WriteLine("'nCut in {0} slices results in an area of {1}'" per slice.", slicesAddFour, areaOfSlice);

                    }

                } //end of else
                Console.Write("'nPlease enter the diameter of your pizza (0 to exit): ");
                diameter = Convert.ToDouble(Console.ReadLine());
                Console.Clear(); // clears console to show new output lines
                // set the need input value back to true for new entry
                needInput = true;
             } // end of while loop
        }
    }
}