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Beginner to Array c#

I don't really understand arrays and I need to create a variable of type 'array of songs' then initialize it to a new Array so it can store 4 references to Songs. How would I then create a loop that would run enough times to fill the array whilst calling the InputSOngDetails() method and store the return value in that method?
namespace Songs
{
class Program
{
static void Main(string[] args) {
InputSongDetails();
}
static Song InputSongDetails()
{
Console.WriteLine("What is the name of your song");
string name = Console.ReadLine();
Console.WriteLine("What is the artists name");
string artist = Console.ReadLine();
int records;
Console.WriteLine("How many records did it sell");
while (!int.TryParse(Console.ReadLine(), out records) || records < 0)
{
Console.WriteLine("That is not valid please enter a number");
}
return new Song(name, artist, records);
}
}
}
This is my Songs class if needed
namespace Songs
{
class Song
{
string name;
string artist;
int copiesSold;
public Song(string name, string artist, int copiesSold)
{
this.name = name;
this.artist = artist;
this.copiesSold = copiesSold;
}
public Song()
{
}
public string GetArtist()
{
return artist;
}
public string GetDetails()
{
return $"Name: {name} Artist: {artist} Copies Sold: {copiesSold},";
}
public string GetCertification()
{
if (copiesSold<200000)
{
return null;
}
if (copiesSold<400000)
{
return "Silver";
}
if (copiesSold<600000)
{
return "gold";
}
return "Platinum";
}
}
}

Fist, initialize your array of songs with new Song[ length ], then a simple for-loop will suffice.
static void Main(string[] args)
{
Song[] songs = new Song[4];
for(int i = 0; i < songs.Length; i++)
{
songs[i] = InputSongDetails();
}
}
Or as the commenters suggest, just use a variable-length List<Song>.
static void Main(string[] args)
{
List<Song> songs = new List<Song>();
for(int i = 0; i < 4; i++)
{
songs.Add(InputSongDetails());
}
}
Once you've mastered the basics, you can also accomplish this with a bit of Linq (though I wouldn't actually recommend it in this case):
static void Main(string[] args)
{
var songs = Enumerable.Range(0, 4)
.Select(i => InputSongDetails())
.ToList();
}

This is not really an answer as much as it is a tip for getting input from the user in a console application which might be useful to you (well, the answer is in the last code snippet, but p.s.w.g has already covered that very well).
Since an interactive console session usually ends up with a lot of Console.WriteLine("Ask the user a question"); string input = Console.ReadLine();, and, as you've already done very well, include some validation on the input in some cases, I've found it handy to write the following methods below.
Each of them take in a string, which is the prompt for the user (the question), and return a strongly-typed variable that represents their input. Validation (when needed) is all done in a loop in the method (as you've done):
private static ConsoleKeyInfo GetKeyFromUser(string prompt)
{
Console.Write(prompt);
var key = Console.ReadKey();
Console.WriteLine();
return key;
}
private static string GetStringFromUser(string prompt)
{
Console.Write(prompt);
return Console.ReadLine();
}
public static int GetIntFromUser(string prompt = null)
{
int input;
int row = Console.CursorTop;
int promptLength = prompt?.Length ?? 0;
do
{
Console.SetCursorPosition(0, row);
Console.Write(prompt + new string(' ', Console.WindowWidth - promptLength - 1));
Console.CursorLeft = promptLength;
} while (!int.TryParse(Console.ReadLine(), out input));
return input;
}
With these methods in place, getting input is as simple as:
string name = GetStringFromUser("Enter your name: ");
int age = GetIntFromUser("Enter your age: ");
And it makes writing the method to get a Song from the user that much easier:
private static Song GetSongFromUser()
{
return new Song(
GetStringFromUser("Enter song name: "),
GetStringFromUser("Enter Artist name: "),
GetIntFromUser("Enter number of copies sold: "));
}
So now our main method just looks like (and this is the answer to your question):
private static void Main()
{
var songs = new Song[4];
for (int i = 0; i < songs.Length; i++)
{
songs[i] = GetSongFromUser();
}
Console.WriteLine("\nYou've entered the following songs: ");
foreach (Song song in songs)
{
Console.WriteLine(song.GetDetails());
}
GetKeyFromUser("\nDone! Press any key to exit...");
}
Additionally, here are some suggestions for improving the Song class.

Processing int to name of list

I try to write a simple console application with Hanoi towers. But I am stuck at one point.
In my program I ask a person to write from to which tower wants to put the disk, but: I have 3 lists as towers, I'll ask for a number from gamer and now how I can build a "compare method"? Because I don't want to copy the same piece of code 6 times...
class Towers : Disks
{
//public Towers(int Value, int WhereItIs) : base(Value, WhereItIs) { }
public List<Disks> Tower1 = new List<Disks>();
public List<Disks> Tower2 = new List<Disks>();
public List<Disks> Tower3 = new List<Disks>();
public void Compare(int dyskFrom, int dyskWhere) {
}
public void Display() {
foreach(var i in Tower1){
Console.WriteLine("Where: {0} | Value: {1}", i.WhereItIs, i.Value);
}
}
public void Build(int TowerHigh) {
for (int i = TowerHigh; i > 0; i--) {
Tower1.Add(new Disks {Value = i, WhereItIs = 1 });
}
}
}
class Disks
{
public int Value; //wartosc krazka
public int WhereItIs; //na ktorej wiezy sie on znajduje
}
class Program
{
static void Main(string[] args)
{
Towers Tower = new Towers();
int TowerHigh;
Console.Write("Podaj wysokość wieży: ");
TowerHigh = int.Parse(Console.ReadLine());
Tower.Build(TowerHigh);
Tower.Display();
Tower.Compare(1, 2);
}
}

It's easier to create an array of Stack<Disk>(). This way you can select a tower by index.
I would use a Stack, because thats typically the functionality you need.
Something like: PSEUDO (typed in browser, no syntax checked)
class Disk
{
public int Size {get; set;}
}
static void Main(string[] args)
{
// create the Stack<Disk> array
Stack<Disk>[] towers = new Stack<Disk>[3];
// create each tower
for(int i=0;i<towers.Length;i++)
{
towers[i] = new Stack<Disk>();
// fill the towers.
for(int j=3;j>0;j--)
towers[i].Enqueue(new Disk { Size = j });
}
bool isHoldingDisk = false;
while(true)
{
DisplayTowers(towers);
if(isHoldingDisk)
Console.WriteLine("On what tower do you want to place it?");
else
Console.WriteLine("Choose a tower to pick a disk");
var key = Console.ReadKey(true);
var chosenTowerIndex = 0;
switch(key)
{
case(Key.Escape):
break;
case(Key.D1):
chosenTowerIndex = 0;
break;
case(Key.D1):
chosenTowerIndex = 1;
break;
case(Key.D1):
chosenTowerIndex = 2;
break;
// etc...
}
if((chosenTowerIndex < 1) || (chosenTowerIndex >= towers.Length))
continue;
// check here if you are holding a disk
if(isHoldingDisk)
{
// logic for testing if you can place the disk here...
// using towers[chosenTowerIndex]
// check if it is completed...
if(completed)
break;
isHoldingDisk = false;
}
else
{
// check if you can pickup a disk....(if there is any)
isHoldingDisk = true;
}
}
// final display...
DisplayTowers(towers);
Console.WriteLine("Thanks for playing");
}
static void DisplayTowers(Stack<Disk>[] towers)
{
// draw some fancy asc-ii art...
}

My C# code on Visual Studio 2013 doesn't work properly

I am trying to be an educated lazy chemistry student, by making a C# program that can do chemistry calculation for me. In order to make the code, I have to understand well the procedures in chemistry class.
I am new to any kind of programming, C# is my first language.
The code works fine for 1 Element calculation, but not 2 Elements calculation.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace ConsoleApplication8
{
class Program
{
static void Main(string[] args)
{
MassCalculation myMassCalculation = new MassCalculation();
TwoMassCalculation myTwoMassCalculation = new TwoMassCalculation();
Console.WriteLine("How many elements are in the compound?");
string userMainInput = Console.ReadLine();
if (userMainInput == "1")
{
myMassCalculation.Amount1 = 1;
Console.WriteLine("What is the ELEMENT?");
string userInput1 = Console.ReadLine();
Elements element;
if (Enum.TryParse<Elements>(userInput1, true, out element))
{
switch (element)
{
case Elements.Na:
myMassCalculation.Element1 = 22.990;
break;
case Elements.Cl:
myMassCalculation.Element1 = 35.453;
break;
default:
break;
}
}
Console.WriteLine("How many?");
string userAmount1 = Console.ReadLine();
int myAmount1 = int.Parse(userAmount1);
myMassCalculation.Amount1 = myAmount1;
myMassCalculation.DoCalculation();
resultOfMassCalculation(myMassCalculation);
}
if (userMainInput == "2")
{
Console.WriteLine("What is the First ELEMENT?");
string userInput1 = Console.ReadLine();
Elements element;
if (Enum.TryParse<Elements>(userInput1, true, out element))
{
switch (element)
{
case Elements.Na:
myMassCalculation.Element1 = 22.990;
break;
case Elements.Cl:
myMassCalculation.Element1 = 35.453;
break;
default:
break;
}
}
Console.WriteLine("How many?");
string userAmount1 = Console.ReadLine();
int myAmount1 = int.Parse(userAmount1);
myMassCalculation.Amount1 = myAmount1;
Console.WriteLine("What is the Second ELEMENT?");
string userInput2 = Console.ReadLine();
if (Enum.TryParse<Elements>(userInput2, true, out element))
{
switch (element)
{
case Elements.Na:
myTwoMassCalculation.Element2 = 22.990;
break;
case Elements.Cl:
myTwoMassCalculation.Element2 = 35.453;
break;
default:
break;
}
}
Console.WriteLine("How many?");
string userAmount2 = Console.ReadLine();
int myAmount2 = int.Parse(userAmount2);
myTwoMassCalculation.Amount2 = myAmount2;
myTwoMassCalculation.DoCalculation();
resultOfMassCalculation(myTwoMassCalculation);
}
Console.ReadLine();
}
private static void resultOfMassCalculation(MassCalculation calculation)
{
Console.Write("The Mass is {0}g/mol", calculation.DoCalculation());
}
}
enum Elements
{
Na,
Cl,
}
class MassCalculation
{
public double Element1 { get; set; }
public int Amount1 { get; set; }
public virtual double DoCalculation()
{
double result = Element1 * Amount1;
return result;
}
}
class TwoMassCalculation : MassCalculation
{
public double Element2 { get; set; }
public int Amount2 { get; set; }
public override double DoCalculation()
{
double result = Element1 * Amount1 + Element2 * Amount2;
return result;
}
}
}
Please help! I know it seems somewhat unprofessional. I have just started programming a week ago, and this is the best I can do. I need guidance.
The only elements defined in the code is Na and Cl, I am trying to calculate NaCl. When everything is in place, I will add more elements to the list, and many more different types of calculations.
I'll take constructive opinions.
Thank you so much in advance.

I refactored your code a little. It will work the same way, but wont crash on inappropriate user input
https://dotnetfiddle.net/CMQugr
using System;
using System.Collections.Generic;
namespace Test
{
public class Program
{
public static Dictionary<string, double> Elements = new Dictionary<string, double>
{
{"Na",22.990},
{"Cl",35.453}
};
public static void Main()
{
double result = 0;
int elemenCountInput;
do
{
Console.WriteLine("How many elements are in the compound?");
} while (!Int32.TryParse(Console.ReadLine(), out elemenCountInput));
for (int i = 0; i < elemenCountInput; i++)
{
string element;
do
{
Console.WriteLine("What is the {0} element", (i + 1));
element = Console.ReadLine();
} while (!Elements.ContainsKey(element));
int amount;
do
{
Console.WriteLine("How many");
} while (!Int32.TryParse(Console.ReadLine(), out amount));
result += Elements[element] * amount;
}
Console.Write("The Mass is {0}g/mol", result);
Console.ReadLine();
}
}
}

There is problem in the code when elements are two. You are assigning the first element value to "myMassCalculation' object and second element value to "myTwoMassCalculation". When you call "DoCalculation()" "myTwoMassCalculation.Element1' and "myTwoMassCalculation.Amount1" have no values. That's why it is giving wrong answer. Make the following changes and try:
if (Enum.TryParse<Elements>(userInput1, true, out element))
{
switch (element)
{
case Elements.Na:
myTwoMassCalculation.Element1 = 22.990;
break;
case Elements.Cl:
myTwoMassCalculation.Element1 = 35.453;
break;
default:
break;
}
}
Console.WriteLine("How many?");
string userAmount1 = Console.ReadLine();
int myAmount1 = int.Parse(userAmount1);
myTwoMassCalculation.Amount1 = myAmount1;

I'd do something like:
Create a class for elements (name (string), whatever that number is (double/decimal)
Create a static dictionary of them of them indexed by name.
Loop through the parameters to Main (or loop around an input command) looking up each entry in the dictionary then perform the calculation.
Convert to LINQ if desired.
This is be a great approach and should teach you a lot. I'm not going to write it for you (time and desire), but I may come back later with an example.

C#: How to write another function for this code?

How would I write another function named noNegatives for this code? I want to rewrite the code with another function named noNegatives but I still want the program to do the same thing.
class Program
{
static void Main(string[] args)
{
string numberIn;
int numberOut;
numberIn = Console.ReadLine();
while (!int.TryParse(numberIn, out numberOut) || numberOut < 0)
{
Console.WriteLine("Invalid. Enter a number that's 0 or higher.");
numberIn = Console.ReadLine();
}
}
}

static void Main(string[] args)
{
int number = NoNegatives();
}
static int NoNegatives()
{
int numberOut;
string numberIn = Console.ReadLine();
while (!int.TryParse(numberIn, out numberOut) || numberOut < 0)
{
Console.WriteLine("Invalid. Enter a number that's 0 or higher.");
numberIn = Console.ReadLine();
}
return numberOut;
}

Follwing is the simplest way you can write it
static void Main(string[] args)
{
int retVal=0;
string numberIn;
int numberOut;
numberIn = Console.ReadLine();
while(noNegatives(numberIn,numberOut)=0)
{
}
}
int noNegatives(String numberIn,int numberOut)
{
numberIn = Console.ReadLine();
if (!int.TryParse(numberIn, out numberOut) || numberOut < 0)
{
Console.WriteLine("Invalid. Enter a number that's 0 or higher.");
return 0;
}
else
{
return 1;
}
}

This question is very similar to the one posted here.
static void Main(string[] args)
{
string numberIn = Console.ReadLine();
int numberOut;
while(!IsNumeric(numberIn))
{
Console.WriteLine("Invalid. Enter a number that's 0 or higher.");
numberIn = Console.ReadLine();
}
numberOut = int.Parse(numberIn);
}
private static bool IsNumeric(string num)
{
return num.ToCharArray().Where(x => !Char.IsDigit(x)).Count() == 0;
}
Since the negative sign is not a digit, IsNumeric will return false for negative numbers.

I need a simple and elegant user validation technique for a c# console application

Coming from a procedural background, I'm running into a conceptual block while designing a menu-based console application and user input validation. My goal is to display a menu that launches other processes. I want to limit user input to 1, 2, or 3 at the menu.
In a procedural language, I would do something like this pseudocode:
10 print "Make a choice"
20 choice = [dataFromKeyboard]
30 if choice < 4 && choice > 0
40 then 10
50 else 60
60 process valid choices
and no matter what I try, I can't get that out of my head while designing an OO program. Consider (simplified to include only 3 menu items):
class Menu
{
public static void Main(String[] args)
{
DisplayMenu thisdm = new DisplayMenu;
int menuChoice = thisdm.displayMenu();
ProcessMenu thispm = new ProcessMenu();
thispm.processMenu(menuChoice);
}
}
class DisplayMenu
{
public int displayMenu()
{
Console.WriteLine("1 - foo3");
Console.WriteLine("2 - foo2");
Console.WriteLine("3 - foo3");
Console.WriteLine("choose");
String choice = Console.ReadLine();
int intChoice = Convert.ToInt32(choice);
return intChoice;
}
}
class ProcessMenu
{
public void processMenu(int choice)
{
switch(choice)
{
case 1:
foo1();
break;
case 2:
foo2();
break;
case 3:
foo3();;
break;
default:
Console.WriteLine("Invalid selection. Please select 1, 2, or 3.");
break;
}
}
}
So here's where I'm stuck. I just can't wrap my head around a simple and elegant way validate my user input that's from an OO rather than procedural standpoint.
Assuming I do the validation in the DisplayMenu, I would be validating after the input is read. But if it turns out to be invalid, how do I re-ask for valid input, since I've already called displayMenu method from Main?
I've been playing with while loops for about an hour, something like this:
intChoice = 0;
[print the menu]
while ((intChoice<1) || (intChoice>3))
Console.WriteLine("Please make a valid choice from the menu");
choice = Console.ReadLine();
etc.
but can't seem to find the sweet spot where I can control user input.
I suspect it's because I'm thinking to procedurally, and not object-oriented enough. Anyone have any tips or input to help me wrap my head around this?

Expanding on #AlexeiLevenkov's suggestion of "turning your classes 90 degrees", I went a step further and created this example of a "Modular" console Application:
class Program
{
static void Main(string[] args)
{
//Retrieve all Module types in the current Assembly.
var moduletypes = Assembly.GetExecutingAssembly()
.GetTypes()
.Where(x => x.IsSubclassOf(typeof(ConsoleModule)));
//Create an instance of each module
var modules = moduletypes.Select(Activator.CreateInstance)
.OfType<ConsoleModule>()
.OrderBy(x => x.Id)
.ToList();
int SelectedOption = -1;
while (SelectedOption != 0)
{
//Show Main Menu
Console.Clear();
Console.WriteLine("Please Select An Option:\n");
modules.ForEach(x => Console.WriteLine(string.Format("{0} - {1}", x.Id, x.DisplayName)));
Console.WriteLine("0 - Exit\n");
int.TryParse(Console.ReadLine(), out SelectedOption);
//Find Module by Id based on user input
var module = modules.FirstOrDefault(x => x.Id == SelectedOption);
if (module != null)
{
//Execute Module
Console.Clear();
module.Execute();
Console.WriteLine("Press Enter to Continue...");
Console.ReadLine();
}
}
}
ConsoleModule class:
public abstract class ConsoleModule
{
public int Id { get; set; }
public string DisplayName { get; set; }
public abstract void Execute();
}
Some sample Modules:
public class EnterUserNameModule : ConsoleModule
{
public EnterUserNameModule()
{
Id = 2;
DisplayName = "User Name";
}
public static string UserName { get; set; }
public override void Execute()
{
Console.WriteLine("Please Enter Your Name: ");
UserName = Console.ReadLine();
}
}
public class HelloWorldModule: ConsoleModule
{
public HelloWorldModule()
{
Id = 1;
DisplayName = "Hello, World!";
}
public override void Execute()
{
Console.WriteLine("Hello, " + (EnterUserNameModule.UserName ?? "World") + "!");
}
}
public class SumModule: ConsoleModule
{
public SumModule()
{
Id = 3;
DisplayName = "Sum";
}
public override void Execute()
{
int number = 0;
Console.Write("Enter A Number: ");
if (int.TryParse(Console.ReadLine(), out number))
Console.WriteLine("Your number plus 10 is: " + (number + 10));
else
Console.WriteLine("Could not read your number.");
}
}
Result:
It uses a little bit of reflexion to find all types deriving from ConsoleModule in the current assembly, then shows a menu with all these options (which are actually properties in this class), and calls the Execute() method when an appropiate option is selected. Much more towards OO way of thinking.

Make your processMenu function return some kind of indicator. You could use exceptions for this instead, but that's overkill.
public bool processMenu(int choice)
{
....
}
If the choice was acceptable, then return true, otherwise return false. Then:
public static void Main(String[] args)
{
DisplayMenu thisdm = new DisplayMenu;
ProcessMenu thispm = new ProcessMenu();
int menuChoice;
do {
menuChoice = thisdm.displayMenu();
} while( !thispm.processMenu(menuChoice) );
}

The way you are doing should be changed. Anyhow, for the same as your question, this works out:
DisplayMenu thisdm = new DisplayMenu();
int menuChoice = -1;
while (menuChoice < 1 || menuChoice > 3)
{
Console.WriteLine("enter valid choice");
menuChoice = thisdm.displayMenu();
}
ProcessMenu thispm = new ProcessMenu();
thispm.processMenu(menuChoice);

the code like:
class Program
{
static void Main(string[] args)
{
DisplayMenu thisdm = new DisplayMenu();
ProcessMenu thispm = new ProcessMenu();
thisdm.displayMenu();
int menuChoice = thispm.GetChoice();
thispm.processMenu(menuChoice);
Console.Read();
}
}
class DisplayMenu
{
public void displayMenu()
{
Console.WriteLine("1 - foo3");
Console.WriteLine("2 - foo2");
Console.WriteLine("3 - foo3");
Console.WriteLine("choose");
}
}
class ProcessMenu
{
public int GetChoice()
{
String choice = Console.ReadLine();
int intChoice = Convert.ToInt32(choice);
while (!Validate(intChoice))
{
Console.WriteLine("Invalid selection. Please select 1, 2, or 3.");
choice = Console.ReadLine();
intChoice = Convert.ToInt32(choice);
}
return intChoice;
}
public void processMenu(int choice)
{
switch (choice)
{
case 1:
//foo1();
break;
case 2:
//foo2();
break;
case 3:
//foo3(); ;
break;
default:
//Console.WriteLine("Invalid selection. Please select 1, 2, or 3.");
break;
}
}
private int[] forChoices=new int[]{1,2,3};
private bool Validate(int choice)
{
if(forChoices.Contains(choice))
{
return true;
}
return false;
}
}