Parallel array

Question

This program is for question 4. When the area code is 262 program is executing well but program is not working for other area codes. Please correct the error. I attach the question.

using System;

namespace _6e4
{
class Program
{
static void Main(string[] args)
{
int[] code = {262, 414, 608, 715, 815, 920};
double[] rate = {0.07, 0.10, 0.05, 0.16, 0.24, 0.14};
double cost;

Console.Write("Enter the area code ");
string s = Console.ReadLine();

Console.Write("Number of minutes talk ");
string t = Console.ReadLine();

for (int x = 0; x < code.Length; ++x)
{
if(Convert.ToInt32(s)==code[x])
{
cost = rate[x] * Convert.ToDouble(t);
Console.WriteLine("Total cost = {0}", cost.ToString("C"));
x = code.Length;
}
Console.ReadKey();
}
}
}
}

Vulpes · Answer

'number' is the argument of type School which is being passed to the CompareTo method. It must therefore have an sEnum property which we can access using the usual 'object.member' syntax.

Maha · Answer

this .sEnum is indicating current instance. number.sEnum (object dot sEnum) is indicating what?

Vulpes · Answer

'number' is a School object and 'this' is the current School object. School has a public int property called sEnum and the value of this property is being used to compare School objects for sorting purposes etc.

Maha · Answer

I couldn't understand the following step. It is obvious this . sEnum is indicating particular instance of the object, this is compared with number.sEnum therefore I assume this also occurrence of the same instance. I do not know what this number.sEnum means. This is Chapter6 of Q12a is attached above. Anybody knows please explain. if (this.sEnum > number.sEnum) class School : IComparable { public string nameSchool { get; set; } public int sEnum { get; set; } public int CompareTo(School number) { int returnVal; if (this.sEnum > number.sEnum) //??????????????? returnVal = 1; else if (this.sEnum returnVal = -1; else returnVal = 0; return returnVal; } }

Vulpes · Answer

You're correct that the 'if' statement will only be executed if the condition evaluates to true. Here zipNo == false and so !zipNo == true. Hence the 'if' statement will execute.

Maha · Answer

I have problem in understanding the IF statement. This program is further simplified to understand the function of IF statement. From this program I understood that IF statement represents the action that will take place only if the expression evaluates as true , whatever way the relevant variable is defined. Here the variable zipNo is defined as bool zipNo = false ; I wish to know whether my understanding is correct. using System; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { bool zipNo = false; if (!zipNo) { Console.WriteLine("Company not delivered to Zip"); } Console.ReadKey(); } } }

Vulpes · Answer

As you know, a bool can either be true or false. So, if it's not true, it's false and, if it's not false, it's true. An 'if' statement only executes if its condition is true. When applied to a bool, the '!' operator changes a true value to false and vice versa. If zipCode is false, then !zipCode is true and so the 'if' statement does execute.

Maha · Answer

Suppose we say input is 2000 therefore program will come out from for loop with value zipNo = true; therefore it can skip the next step, because its condition is !zipNo. There is no problem of understanding this. Suppose we say input does not match the given zip code. bool zipNo = false ; is define in the program therefore if(!zipNo) means if(notFalse) as this is opposite to what was define in the program, in this circumstances how program can execute the statement within the if .

Vulpes · Answer

If zipNo is false, then the code writes to the console: "Company not delivered to Zip " followed by whatever the user input. zipNo will be false if whatever zip code the user entered is not in the array.

Maha · Answer

This is originally Vulpes idea. I applied to simple question. Chapter6 is attached Q(2). I wish to know how does the following code function if (!zipNo) { Console .WriteLine( "Company not delivered to Zip {0}" , s); } using System; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { string[] zip = new string[5] { "1000", "2000", "3000", "4000", "5000" }; Console.Write("Entre a ZIP code "); string s = Console.ReadLine(); bool zipNo = false; for (int x = 0; x { if (Equals(s, zip[x])) { Console.WriteLine("Company dilivers {0}", zip[x]); zipNo = true; x = zip.Length; } } if (!zipNo) { Console.WriteLine("Company not delivered to Zip {0}", s); //????????????????? } Console.ReadKey(); } } }

Vulpes · Answer

The CompareTo method should be: public int CompareTo(Friends fName) { int returnVal; int x = string.Compare(this.name, fName.name); if (x > 0) // test is > 0 not 1 returnVal = 1; else if (x returnVal = -1; else returnVal = 0; return returnVal; } However, you could shorten it to: public int CompareTo(Friends fName) { return string.Compare(this.name, fName.name); }

Maha · Answer

How to use CompareTo() & string. This Q13(a) of the 229.zip. I have attached the program. Problem is in the last part of the program.

Vulpes · Answer

That's because you've missed off a pair of braces. This code: if (school[x].sEnum > number) Console.WriteLine("SCHOOL NAME {0} NUMBER OF STUDENTS {1}", school[x].nameSchool, school[x].sEnum); minEnrollExists = true; should be: if (school[x].sEnum > number) { Console.WriteLine("SCHOOL NAME {0} NUMBER OF STUDENTS {1}", school[x].nameSchool, school[x].sEnum); minEnrollExists = true; }

Maha · Answer

It is not working. I have attached the work.

Vulpes · Answer

Just change the final 'for' statement in Main() to the following: bool minEnrollExists = false; for(x = 0; x { if (school[x].sEnum >= number) { Console.WriteLine("SCHOOL NAME {0} NUMBER OF STUDENTS {1}", school[x].nameSchool, school[x].sEnum); minEnrolExists = true; } } if (!minEnrollExists) { Console.WriteLine("THERE IS NO ENROLLMENT FIGURE OF AT LEAST {0}", number); } Console.ReadKey();

Maha · Answer

This question is 12(b) of 229.zip. "THERE IS NO ENROLLMENT FIGURE MORE THAN....." This message must come on the console screen when appropriate. How it is possible because if-else statement can't be used in this for loop.

Vulpes · Answer

The program's fine. If you want to use foreach instead of for, the code will be: using System; namespace _6e11 { class CarRecords { static void Main(string[] args) { Car[] car = new Car[5]; car[0] = new Car(1111, "Fiat", "11000", "Black", 5000); car[1] = new Car(2222, "Honda", "2000", "Red", 6000); car[2] = new Car(3333, "Camery", "XYZ100", "Green", 7000); car[3] = new Car(4444, "Nissan", "JXA300", "Blue", 8000); car[4] = new Car(5555, "Moris", "3BS100", "White", 9000); DisPlayFleet(car[0], car[1], car[2]);//18,000 DisPlayFleet(car[0], car[1], car[2], car[3]);//26,000 DisPlayFleet(car[0], car[1], car[2], car[3], car[4]);//35,000 Console.ReadKey(); } public static void DisPlayFleet(params Car[] cArray) { int sum=0, carPrice=0; int x = 0; foreach(Car car in cArray) { sum = sum + car.price; carPrice = car.price; Console.WriteLine("Price of Car[{0}] = {1}", x, carPrice.ToString("C")); x++; } Console.WriteLine("Sum = {0}", sum.ToString("C")); Console.WriteLine(); } } } class Car { public int idNumber { get; set; } public string make { get; set; } public string model { get; set; } public string colour { get; set; } public int price { get; set; } public Car(int idNumber, string make, string model, string colour, int price) { this.idNumber = idNumber; this.make = make; this.model = model; this.colour = colour; this.price = price; } }

Maha · Answer

I used Automatic Properties to do this question. Anyone could check it please for error. Also let me know how to use "foreach" instead of the place where "for" statement presence.(Q11 229.zip) using System; namespace _6e11 { class CarRecords { static void Main(string[] args) { Car[] car = new Car[5]; car[0] = new Car(1111, "Fiat", "11000", "Black", 5000); car[1] = new Car(2222, "Honda", "2000", "Red", 6000); car[2] = new Car(3333, "Camery", "XYZ100", "Green", 7000); car[3] = new Car(4444, "Nissan", "JXA300", "Blue", 8000); car[4] = new Car(5555, "Moris", "3BS100", "White", 9000); DisPlayFleet(car[0], car[1], car[2]);//18,000 DisPlayFleet(car[0], car[1], car[2], car[3]);//26,000 DisPlayFleet(car[0], car[1], car[2], car[3], car[4]);//35,000 Console.ReadKey(); } public static void DisPlayFleet(params Car[] cArray) { int sum=0, carPrice=0; for (int x = 0; x //how to use foreach instead of for { sum = sum + cArray[x].price; carPrice = cArray[x].price; Console.WriteLine("Price of Car[{0}] = {1}", x, carPrice.ToString("C")); } Console.WriteLine("Sum = {0}", sum.ToString("C")); Console.WriteLine(); } } } class Car { public int idNumber { get; set; } public string make { get; set; } public string model { get; set; } public string colour { get; set; } public int price { get; set; } public Car(int idNumber, string make, string model, string colour, int price) { this.idNumber = idNumber; this.make = make; this.model = model; this.colour = colour; this.price = price; } }

Vulpes · Answer

Sure, here it is: //pdf241 using System; public class Prices { public static void Main() { double[] pArray = new double[20]; double sum = 0, average = 0; for (int x = 0; x { Console.Write("Prices #{0} $", x + 1); pArray[x] = Convert.ToDouble(Console.ReadLine()); sum += pArray[x]; } average = sum / pArray.Length; Console.WriteLine("
Total: {0}", sum.ToString("c")); Console.WriteLine("
Prices less than $5.00"); Console.WriteLine("----------------------"); for (int x = 0; x if (pArray[x] Console.WriteLine("Prices #{0} ${1}", x + 1, pArray[x]); Console.WriteLine("
Average: ${0}", average.ToString("f2")); Console.WriteLine("
Prices higher than average"); Console.WriteLine("--------------------------"); for (int x = 0; x if (pArray[x] > average) Console.WriteLine("Prices #{0} ${1}", x + 1, pArray[x]); Console.WriteLine(); Console.ReadKey(); } }

Maha · Answer

This program is Question 9 of the 229.ZIP. I tried to do by using double [] prices = new double [20]; but couldn't therefore I used Prices [] pArray = new Prices [20]; and did the program. The program is as follows. If you could do the program by using double[] prices = new double[20] ; it is highly appreciated. //pdf241 using System; public class Prices { public static void Main() { Prices[] pArray = new Prices[20]; ; double ePrice, sum = 0, average = 0; for (int x = 0; x { pArray[x] = new Prices(); Console.Write("Prices #{0} $", x + 1); ePrice = Convert.ToDouble(Console.ReadLine()); pArray[x].SetPrice(ePrice); sum = sum + ePrice; average = sum / pArray.Length; } Console.WriteLine("
Total: {0}", sum.ToString("c")); Console.WriteLine("
Prices less than $5.00"); Console.WriteLine("----------------------"); for (int x = 0; x if (pArray[x].GetPrice() Console.WriteLine("Prices #{0} ${1}", x + 1, pArray[x].GetPrice()); Console.WriteLine("
Average: ${0}", average.ToString("f2")); Console.WriteLine("
Prices higher than average"); Console.WriteLine("--------------------------"); for (int x = 0; x if (pArray[x].GetPrice() > average) Console.WriteLine("Prices #{0} ${1}", x + 1, pArray[x].GetPrice()); Console.WriteLine(); Console.ReadKey(); } } class Prices { double values; public double GetPrice() { return values; } public void SetPrice(double p) { values = p; } }

Vulpes · Answer

The criterion for creating a new class, rather than using an existing class (or struct), is whether it really adds anything to the latter. I'd certainly agree that if an object requires more than one field then a separate class is necessary. The reason why I'm drawing a distinction between fields and properties is because you can have properties which don't have backing fields as such or share the same field with other properties. For example, if you did create a Price class, with one field '_value' of type double, then you could define these properties: public double Value { get { return _value; } set { _value = value; } } public bool IsLessThanFive { get { return _value } In the context of the program you're being asked to write, it's just not worth creating a separate class so you can define an IsLessThanFive property - you can do that perfectly well using a double directly or by defining a method which takes a double as a parameter.

Maha · Answer

I wish to know is there any criteria do decide whether to create a separate price class or not. In my view if the object contains more than one property separate class is necessary. I wish to know whether my understanding is correct. For example in a question ( Employee empArray = new Employee [7];) the object empArray contains employee ID and salary and you have to use these two properties to derive answer therefore separate class in necessary.

Vulpes · Answer

If I were answering this question, I'd assume there was no need to create a separate Price class as all it would consist of is a double value. So I'd use: double [] prices = new double [20];

Maha · Answer

I am very sorry for the mistake. I have attached.

Vulpes · Answer

The attachment doesn't cover question 9. It only covers questions 4 to 8 inclusive.

Maha · Answer

This is regarding the question 9 in the attached material. Is there any way to decide whether program needs this code Prices [] prices = new Prices [20]; or double [] prices = new double [20];

Vulpes · Answer

As price is a double variable, when you place a dot after it, the compiler is expecting to find an instance member of the System.Double structure. There isn't a member called 'percentcommission' and (if you know what extension methods are) there isn't one of those either which is in scope and can apply to a double instance. Hence the error.

Maha · Answer

Following program is working well. At the beginning by mistake I have put dot(.) instead of * operator as a result I received an error message, but I couldn't understand that. I wish to know how to understand the error message. Error message 'double' does not contain a definition for 'percentcommission' and no extension method 'percentcommission' accepting a first argument of type 'double' could be found (are you missing a using directive or an assembly reference?) using System; public class Commission { public static void Main() { double[] carprices = {0, 15000, 24000}; double[] percentcommission = {0.05, 0.07, 0.10}; int x = 2; Console.Write("Enter the car price: $"); double price = Convert.ToDouble(Console.ReadLine()); while (x >= 0 && price --x; Console.WriteLine("Commission: {0}", (price . percentcommission[x]).ToString("c")); //dot(.) instead of * Console.ReadKey(); } }

Vulpes · Answer

If you change this line: while (x >= 0 && miles --x; to this: while (x >= 0 && miles --x; and enter, say, 400 miles then the while loop will carry on until x reaches 0 because 400 is always less than 500. When x reaches 0, it will then be decremented to -1 and the next iteration of the while loop will not take place because x is no longer >= 0. ticketprice[x] will then give an index out of range exception because x is -1.

Maha · Answer

This program is working well. But if we change the distance[x] by 500, program is working only for distance 500 input but not for any other distance input. I don't know why anyone knows please tell the reason. In the attached material question number 5 while (x >= 0 && miles while (x >= 0 && miles using System; public class WhippetBus { public static void Main() { double[] distance = { 0, 100, 300, 500 }; int[] ticketprice = { 25, 40, 55, 70 }; int x = 3; Console.Write("Enter Distance in miles: "); double miles = Convert.ToDouble(Console.ReadLine()); while (x >= 0 && miles distance[x] ) --x; Console.WriteLine("Ticket Price for {0} mile is {1}", miles, ticketprice[x].ToString("c")); Console.ReadKey(); } } /* Enter Distance in miles: 400 Ticket Price for 400 mile is $55.00 Enter Distance in miles: 700 Ticket Price for 700 mile is $70.00 */

Vulpes · Answer

Well, apart from having Console.ReadKey() in the wrong place (it should be below the next right brace), the program looks fine to me. What makes you think it's not working properly for codes other than 262?

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Answers (31)