Loop problem help plz

Thank you very much for your explanation.

It is a greatly valuable explanation because I had many confusion over using the FOR loop, breaking loop with i = size.Length; and using the Reversed Keyword BREAK. Your explanation solved all the problems.

If you do that, you'll get an exception because 'i' will still be set to the value which it was given in the last 'for' loop, namely:

  i = size.Length;

which will be outside the range of the price array.

However, if you'd replaced the above line with:

   break; // the usual way to exit loops

then it would have worked.

If I comment out this line (//for (i = 0; i < size.Length; ++i)) and leave other line, program is still not executing why? Because price[i] is the price obtain in the for loop (highlighted in blue)

//for (i = 0; i < size.Length; ++i)
tPriceBeforeDis = price[i] * num;

using System;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
int x = 4, i;
double tPriceBeforeDis = 0, tPriceAfterDis = 0, pSize = 0;

string[] size = new string[4] { "S", "M", "L", "X" }; //i=3
double[] price = new double[4] { 6.99, 8.99, 12.50, 15 }; //i=3

int[] numberRangeLmit = new int[5] { 1, 2, 3, 4, 5 }; //x=4
double[] discount = new double[5] { 0, 0.1, 0.15, 0.15, 0.20 }; //x=4

Console.WriteLine("Pizza size - S M L X");
Console.Write("Which size you want ");
string s = Console.ReadLine();

for (i = 0; i < size.Length; ++i)
{
if (s == size[i])
{
Console.WriteLine("Price of a Pizza is {0}", price[i].ToString("C"));
//pSize = price[i]; //(1) comment out
i = size.Length;
}
}
Console.Write("\nHow many Pizza you want ");
int num = Convert.ToInt32(Console.ReadLine());

//for (i = 0; i < size.Length; ++i)
tPriceBeforeDis = price[i] * num; //?????????????????????????

//tPriceBeforeDis = pSize * num; //(2) comment out


Console.WriteLine("\nTotal price before discount is {0}", tPriceBeforeDis.ToString("C"));

while (x >= 0 && num < numberRangeLmit[x])
--x;

tPriceAfterDis = tPriceBeforeDis - (tPriceBeforeDis * discount[x]);

Console.WriteLine("Price after discount ({0}% discount) {1}", discount[x], tPriceAfterDis.ToString("C"));

Console.ReadKey();
}
}
}

When this code is executed:

for (i = 0; i < size.Length; ++i)
    tPriceBeforeDis = price[i] * num;

tPriceBeforeDIS will be successively overwritten until it's eventually set to the price for the largest size of pizza (i.e. $15 each) multiplied by the number of pizzas required.

Previously, when you had this:

    pSize = price[i];

    // and later

    tPriceBeforeDis = pSize * num;

pSize was being set to the price for the size of pizza which was actually being ordered and this was then being multiplied by the number of pizzas required to arrive at tPriceBeforeDis.

Please unzip the file. You can see the problem.

When I comment out step (1) and (2) (highlighted in yellow) instead I inserted above code in (highlighted in blue) program is giving incorrect output. Anyone knows the reason?

Following is the incorrect output 

/*
Pizza size - S M L X
Which size you want S
Price of a Pizza is $6.99

How many Pizza you want 1

Total price before discount is $15.00
Price after discount (0% discount) $15.00
*/

using System;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
int x = 4, i;
double tPriceBeforeDis = 0, tPriceAfterDis = 0, pSize=0;

string[] size = new string[4] {"S","M","L","X"}; //i=3
double[] price = new double[4] {6.99, 8.99, 12.50, 15}; //i=3

int[] numberRangeLmit = new int[5] {1, 2, 3, 4, 5}; //x=4
double[] discount = new double[5]{0, 0.1, 0.15, 0.15, 0.20}; //x=4

Console.WriteLine("Pizza size - S M L X");
Console.Write("Which size you want ");
string s = Console.ReadLine();

for (i = 0; i < size.Length; ++i)
{
if (s == size[i])
{
Console.WriteLine("Price of a Pizza is {0}", price[i].ToString("C"));
pSize = price[i];
i = size.Length;
}
}
Console.Write("\nHow many Pizza you want ");
int num = Convert.ToInt32(Console.ReadLine());

tPriceBeforeDis = pSize * num;

Console.WriteLine("\nTotal price before discount is {0}", tPriceBeforeDis.ToString("C"));

while (x >= 0 && num < numberRangeLmit[x])
--x;

tPriceAfterDis = tPriceBeforeDis - (tPriceBeforeDis * discount[x]);

Console.WriteLine("Price after discount ({0}% discount) {1}", discount[x], tPriceAfterDis.ToString("C"));

Console.ReadKey();
}
}
}

Vuples, as you can see from the comment out code I was trying to multiple by userInput1 when i realized its wrong , so I was trying to figure out which variable/input I need to use but I just cant figure it out......... i tried to multiply by pizzaPrice[x] but it tells me x does not exist in the current context, could you help me?


  string[] pizzaSize = { "S", "M", "L", "G" }
            double[] pizzaPrice = { 6.99, 8.99, 12.50, 15.00 };

  while (true)
  {
  Console.Write("Enter pizza size: ");
  string userInput = Console.ReadLine().ToUpper();
  Console.WriteLine("Please enter how many pizzas you need: ");
  double userInput1 = Convert.ToDouble(Console.ReadLine());

  int foundIndex =-1;
  double firstDiscount = 0, secondDiscound = 0, thirdDiscount = 0;

  //if( userInput1 == 2)

  //  firstDiscount = userInput1 * .10;

  //Console.WriteLine("Due to discount of 10% your total price is {0}", firstDiscount);

  //if (userInput1 == 3 || userInput1 == 4)

  //  secondDiscound = userInput1 * .15;

  //Console.WriteLine("Due to discount of 10% your total price is {0}", secondDiscound);

  //if (userInput1 >= 5)

  //  thirdDiscount = userInput1 * .20;

  //Console.WriteLine("Due to discount of 10% your total price is {0}", thirdDiscount);

  for (int x = 0; x < pizzaSize.Length; ++x)
  {
  if (userInput == pizzaSize[x])
  {
  foundIndex = x;
  }
  }
  if (foundIndex > -1)
  {
  if (userInput1 == 2)

  firstDiscount =pizzaPrice[x] * .10;

  Console.WriteLine("Due to discount of 10% your total price is {0}", firstDiscount);

  if (userInput1 == 3 || userInput1 == 4)

  secondDiscound = * .15;

  Console.WriteLine("Due to discount of 15% your total price is {0}", secondDiscound);

  if (userInput1 >= 5)

  thirdDiscount =  * .20;

  Console.WriteLine("Due to discount of 20% your total price is {0}", thirdDiscount);

  Console.WriteLine("The price of a size {0} pizza is {1:C}", userInput, pizzaPrice[foundIndex]);
  return;
  }
  else
  {
  Console.WriteLine("Invalid size, please try again");
  }

You need to assign an initial value which is not a valid array index.

The usual choice for this type of 'find' routine is -1.

Compare, for example, the String.IndexOf method in the .NET framework:

http://msdn.microsoft.com/en-us/library/kwb0bwyd.aspx

Vulpes why did u assign -1 to foundIndex? why not 0?

Yes, you can do it using arrays. I'll just do the first part and leave you to do the second: