greetings, im am new to programming and at the moment developing a clone of the game battleships. i need to implement a fleet of 5 ships. this is what i have done so far:
class Cell holds the status of a table cell:
public class Cell
{
// class for holding cell status information
public enum cellState
{
WATER,
SCAN,
SHIPUNIT,
SHOT,
HIT
}
public Cell()
{
currentCell = cellState.WATER;
}
public Cell(cellState CellState)
{
currentCell = CellState;
}
public cellState currentCell { get; set; }
}
class GridUnit holds table cell info:
public class GridUnit
{
public GridUnit()
{
Column = 0;
Row = 0;
}
public GridUnit(int column, int row)
{
Column = column;
Row = row;
}
public int Column { get; set; }
public int Row { get; set; }
}
finally class Shipunit contains both the above classes and acts as a wrapper for state info of an individual cell:
public class ShipUnit
{
public GridUnit gridUnit = new GridUnit();
public Cell cell = new Cell(Cell.cellState.SHIPUNIT);
}
at the moment i am thinking about implementing the fleet info in a Jagged Array like this:
ShipUnit[][] Fleet = new ShipUnit[][]
{
new ShipUnit[] {ShipUnit,ShipUnit,ShipUnit,ShipUnit,ShipUnit},
new ShipUnit[] {ShipUnit,ShipUnit,ShipUnit,ShipUnit},
new ShipUnit[] {ShipUnit,ShipUnit,ShipUnit}
new ShipUnit[] {ShipUnit,ShipUnit,ShipUnit}
new ShipUnit[] {ShipUnit,ShipUnit}
};
i realize the last bit of code does not work. it is only for presenting the idea.
but the problem being i need a field that states what type of ship each line of jagged array represent and i dont think it is practical to state this info in every cell information.
so i would like some ideas of implementation of this issue from you.
thank you.
class Ship
{
ShipUnit[] shipUnits;
string type;
public Ship(int length, string type)
{
shipUnits = new ShipUnit[length];
this.type = type;
}
}
Ship[] fleet = new Ship[5];
fleet[0] = new Ship(5, "Carrier");
fleet[1] = new Ship(4, "Battleship");
fleet[2] = new Ship(3, "Submarine");
fleet[3] = new Ship(3, "Something else");
fleet[4] = new Ship(2, "Destroyer");
I think I would define an owning Grid class, the holds all of the GridUnits. Then this Grid would also hold a List. A Ship would just have properties like size, orientation, BowCell. When adding a ship to the grid, the Grid could set the status of the units accordingly.
This way, you can have usefull methods on the ship level like IsSunk(), OccupiesUnit(), etc...
Why don't you create something like this
class Ship
{
public ShipUnits[] _SUParts;
public String _strType;
public Ship(String styType, int NbPart)
{
_SUParts = new ShipUnit[length];
_strType = strType;
}
}
that being said, I would not put all members public. I'de use Getter/Setter to change the values
I assumed by type you also mean the name of the ship (destroyer,etc.)
How many types of ships are there. Is that fixed or variable at runtime?
If it is fixed and not too many, you should probably just use separate arrays for each. If they are variable AND you have only one array for each type, you could use a generic dictionary (of enumShipUnitType, ShipUnit[]).
You can then iterate over the dictionary by getting the KeyValuePair from it like so.
For Each kvp As KeyValuePair(Of enumShipUnitType, ShipUnit[]) In m_dictShipUnits
For each oShipUnit as Shipunit in kvp.Value
'Do whatever
Next
Next
class Ship {
public Size Size { get; set; }
public Orientation Orientation { get; set; }
public Point Position { get; set; }
public Boolean Sunk { get; set; }
public String Name { get; set; }
[...]
}
Inherit from Ship and create sub classes like Battleship, Cruiser, etc for the different ships. Add a "IsHit(Point shot)" method that compares Size, Orientation, Position and the shot position (the Rectangle class has many nice functions for that).
class Grid {
private Size size = new Size(10, 10);
private List<Ship> ships = new List<Ship>();
private List<Point> shots;
[...]
}
Create two grids (one for each player), add a shoot method that calls IsHit for every Ship and then adds the shot to shots. After each move if every point of a ship is hit (is in shots) and set the ship to Sunk if all are hit.
Related
I have an application where i have say 10 objects of different types. I wish to have them in same list and iterate through them on many occasions. I cant push them into one list because they are of different types. So i created an interface and created a property that all objects share. Now i have the list of objects and type of the list is the "interface". When i iterate through the object, i can't access the specific properties of the object because the compiler will only know at runtime what object it is. So if i try to code Object_A.Name, visual studio will show error because it doesn't know they type of object. I can obviously do an if else or something similar to find the type of object and cast it, but i want to know of there is a better way, or if this whole approach of having an interface is wrong and if i should have begun in a different direction.
In the code below, i want to get the Devname, which i can't because its not part of the interface, but belongs to every object. I could make it part of the interface, but every now and then i may need to get a specific property. hence wanting to know if there is a way to do it.
foreach (ICommonDeviceInterface device in Form1.deviceList)
{
if (device.DevName.Equals(partnername))
{
return device.Port[portNo].PortRef;
}
}
One way you could do this is by using reflection to try to get the property value of a named property from an object, using a helper method like:
public static object GetPropValue(object src, string propName)
{
return src?.GetType().GetProperty(propName)?.GetValue(src, null);
}
Credit for above code goes to: Get property value from string using reflection in C#
This requires no checking types or casting, it just returns the value of the property, or null if it doesn't contain the property.
In use it might look like:
private static void Main()
{
// Add three different types, which all implement the same interface, to our list
var devices = new List<ICommonDeviceInterface>
{
new DeviceA {DevName = "CompanyA", Id = 1},
new DeviceB {DevName = "CompanyB", Id = 2},
new DeviceC {Id = 3},
};
var partnerName = "CompanyB";
foreach (var device in devices)
{
// Try to get the "DevName" property for this object
var devName = GetPropValue(device, "DevName");
// See if the devName matches the partner name
if (partnerName.Equals(devName))
{
Console.WriteLine($"Found a match with Id: {device.Id}");
}
}
}
Classes used for the sample above:
interface ICommonDeviceInterface
{
int Id { get; set; }
}
class DeviceA : ICommonDeviceInterface
{
public int Id { get; set; }
public string DevName { get; set; }
}
class DeviceB : ICommonDeviceInterface
{
public int Id { get; set; }
public string DevName { get; set; }
}
class DeviceC : ICommonDeviceInterface
{
public int Id { get; set; }
}
Use "as" and "is" to know what type of interface
public class A : ICommonDeviceInterface
{
public int AMember;
}
public class B :ICommonDeviceInterface
{
public int BMember;
}
foreach (ICommonDeviceInterface device in Form1.deviceList)
{
if(device is A)
{
A a = device as A;
a.AMember = 100;
}
else if(device is B)
{
B b = device as B;
b.BMember = 123;
}
}
New here, I've been learning c# for about a month.
Anyway, I've been searching StackOverflow for a couple of days now and couldn't find a specific answer to my problem...
//Here's my Class
public class Guy
{
public static int ID { get; set; }
public static int LifeExpectancy { get; set; }
public static bool Living { get; set; }
public Guy(int id, int lifeExpectancy, bool living)
{
ID = id;
LifeExpectancy = lifeExpectancy;
Living = living;
}
}
What I'm trying to do is create a specific number of "someGuy" objects to then put them into a public list using this method...
public static List<Guy> Guys = new List<Guy>();
public static void makeSomeGuys(int howManyGuys)
{
for (int i = 0, i <= howManyGuys; i++)
{
int id = i;
int lifeExpectancy = 80;
bool alive = true;
Guys.Add(New Guy(id, lifeExpectancy, alive));
Console.WriteLine("Made a new Guy {0}", id);
}
return;
}
Questions in order of importance:
How do I access a specific object as well as its parameters? (Accessing from the list "Guys".)
How do I access an object from this list in another class? (Not that I absolutely need to, I'm curious)
Can I search for an object in a list by using its parameters? (As opposed to doing something like... humanPopulation[number])
Should I create a new list for objects that have had their parameters modified? (As opposed to leaving it in the original list)
Is it possible to remove items from a list? (Just in general, is that a thing people do? if so, why?)
I really only need the first question answered. The rest of them are just a bonus. Thanks!
First you need to remove the static modifier from the properties of the Guy class, i.e.:
public int ID { get; set; }
public int LifeExpectancy { get; set; }
public bool Living { get; set; }
because static causes the property to be an attribute of the class itself, rather than the instances of the class (the individual 'guys').
To access life expectancy of the first guy (the zeroth):
Console.WriteLine(Guys[0].LifeExpectancy);
To access life expectancy of the fifth guy:
Console.WriteLine(Guys[4].LifeExpectancy);
using System;
using System.Collections.Generic;
using System.Linq;
namespace test
{
public class Guy
{
private int m_ID;
private int m_LifeExpectancy;
private bool m_Living;
public int ID
{
get { return m_ID; }
set { m_ID = value; }
}
public int LifeExpectancy
{
get { return m_LifeExpectancy; }
set { m_LifeExpectancy = value; }
}
public bool Living
{
get { return m_Living; }
set { m_Living = value; }
}
public Guy(int id, int lifeExpectancy, bool living)
{
ID = id;
LifeExpectancy = lifeExpectancy;
Living = living;
}
}
public class MyFactory
{
public IList<Guy> MakeSomeGuys(int howManyGuys)
{
IList<Guy> localGuys = new List<Guy>();
for (int i = 0; i <= howManyGuys; i++)
{
int id = i;
int lifeExpectancy = 80;
bool alive = true;
localGuys.Add(new Guy(id, lifeExpectancy, alive));
Console.WriteLine("Made a new Guy {0}", id);
}
return localGuys;
}
}
public class program
{
public void Main()
{
MyFactory mf = new MyFactory();
IList<Guy> guys = mf.MakeSomeGuys(5);
//How do I access a specific object as well as its parameters? (Accessing from the list "Guys".)
int GetFirstGuyId = guys.FirstOrDefault().ID; //LEARN LINQ
//How do I access an object from this list in another class? (Not that I absolutely need to, I'm curious)
//you need to learn about object oriented encapsulation for better understanding.
//Can I search for an object in a list by using its parameters? (As opposed to doing something like...humanPopulation[number])
Guy guyById = guys.Where(g => g.ID == 5).FirstOrDefault(); // returns the first match (need to learn lambda expression)
//Should I create a new list for objects that have had their parameters modified? (As opposed to leaving it in the original list)
// you need to learn about passing values by value / reference (by reference you already changing the original!).
//Is it possible to remove items from a list? (Just in general, is that a thing people do? if so, why?)
//yes
guys.Remove(guyById);
}
}
}
You're likely new to C# and OO programming, so I've included some good links in this answer.
Regarding question 1 only:
Firstly, your Guy class properties aren't properly encapsulated. Make sure you properly scope the ID, LifeExpectancy and Living properties like shown in this article.
If you'd like to access a specific item, that is, a Guy with a particular ID, you'd be better off using an associative container like Dictionary.
If you're happy with the List container, you need to use the Find method on Guys as shown in the example at the link. You'll notice the term Predicate in the documentation, this link will elaborate.
public class Price
{
public string Symbol {get; set; }
public double AskPrice{get; set; }
public double BidPrice{get; set; }
public string Exchange{get; set; }
}
public class inputs
{
public IList<Price> Prices {get; set; }
}
var inputs = new
{
Prices = prices,
};
Price[] p = inputs.Prices.Where(x => x.Exchange == exchange).ToArray();
p.ForEach(x => x.AskPrice = 0);
For this code when I create new variable p, it is actually a reference to input.price, not a new variable. Why is this? Is there any best practice of how to deal with this behavior?
You did not make a change to p, p stayed the same, what you changed where the elements inside of p, the elements inside of p are shared between p and the original source.
To not get this behavior you need to "Deep copy" the objects when you make a new array, creating new objects for the elements with the same content as the original.
public class Price
{
public string Symbol {get; set; }
public double AskPrice{get; set; }
public double BidPrice{get; set; }
public string Exchange{get; set; }
public Price Clone()
{
var result = new Price();
result.Symbol = this.Symbol;
result.AskPrice = this.AskPrice;
result.BidPrice = this.BidPrice;
result.Exchange = this.Exchange;
return result;
}
}
public class inputs
{
public IList<Price> Prices {get; set; }
}
var inputs = new
{
Prices = prices,
};
Price[] p = inputs.Prices.Where(x => x.Exchange == exchange).Select(x=> x.Clone()).ToArray();
p.ForEach(x => x.AskPrice = 0);
Note, if you have any reference types inside of your class you need to recursively clone the entire data structure and will need to make copies of them too.
There are two different variables here - the first is the Price object(s), and the second is input.Prices, which is a List of prices.
Your LINQ code takes the inputs.Prices list, filters it and creates a new array from it, but all that does is create new collections. It doesn't change the actual objects that are in the collection. This is because classes, in C#, are all reference types, meaning that var price = input.Prices[0] just copies the reference to a single, specific instance in memory. You can copy those references between a dozen lists and arrays, but the objects are the same.
It seems that what you want is to clone or copy by value your Price objects. For that, you have two options:
Make Price a struct.
Structs, unlike classes, are value types and are copied-by-value, meaning a new copy is made whenever you assign it to a new variable. This, however, has a performance penalty, since the whole struct is copied every time it's assigned. Your struct takes up 24-32 bytes (two 64bit doubles and two 32/64 bit references to strings), which is more than the recommended rule of thumb of "no more than 16 bytes for structs", so it's probably a bad idea.
Make a Clone method.
Have your Price implement a Clone method which returns a copy of the object - or alternately, create a copy-constructor that creates a new Price with the old values. Use that in your LINQ:
public class Price
{
// your fields
public Price Clone()
{
return new Price
{
Symbol = this.Symbol,
BidPrice = this.BidPrice,
//etc.
}
}
}
var p = input.Prices.Where(x => x.Exchange == exchange).Select(x => x.Clone()).ToArray();
I have the following struct defined in a user control:
public struct ColumnData
{
public string ColumnName { get; set; }
public string ColumnDataItem { get; set; }
public bool ColumnIsHyperLink { get; set; }
public string ColumnHyperLinkURL { get; set; }
public string ColumnHyperLinkPK { get; set; }
}
I create a new instance of List<ColumnData> (In a different code behind that creates an instance of the user control) and want to pass in values to it, but how do I assign them to specific attributes within the struct object?
I create an instance of the struct using the following code:
List<ColumnData> DataItems = new List<ColumnData>();
This:
List<ColumnData> DataItems = new List<ColumnData>();
creates a new list.
This:
List<ColumnData> DataItems = new List<ColumnData>();
var cd = new ColumnData();
cd.ColumnName = "Taco";
DataItems.Add(cd);
creates a new list, a new struct, and adds an item to the list.
Change that to a class; all your woes relating to modifying struct properties (etc) will go away.
Alternatively, make it an immutable struct, and initialize it with the correct values at the point of creation - then the issue is moot, no matter how many times it is subsequently copied.
IMO the first is the right approach here.
so you need to do this:
public void AddToList(ColumnData columnData)
{
DataItems.Add(columnData);
}
and call this method from your other class passing an already created and initialized columnData object.
List<ColumnData> DataItems = new List<ColumnData>();
Is creating the list that holds your structs not your structs itself.
You could use structs here for performance reasons (faster then classes).
ColumnData data = new ColumnData
{
ColumnName = "Blaa"
};
DataItems.Add(data);
This is probably a simple question. Suppose I have a object called Users and it contains a lot of protected variables.
Inside that Users class I have a method that creates a temporary Users object, does something with it, and if successful, transfers all the variables from the temp Users object into the one I have.
Is there some fast way to transfer all the variables from one Users object into another Users object without doing this using C#?
this.FirstName = temp.FirstName;
this.LastName = temp.LastName;
........75 variables later......
this.FavoriteColor = temp.FavoriteColor
A better approach is to implement the IClonable interface. But you'll find it doesn't save you a lot of work.
You should check out cloning in C#.
Deep cloning objects
I think serializing and then deserializing an object will create a new object instance. This should be identical to the former object.
A better solution might be to move whatever this method is outside of your class, and then just assign the temp user object to your main user object reference like so:
_User = tmpUser;
sparing you the 75 lines of code. Whenever I have a class creating an instance of itself inside one of its own methods, I always like to blink a couple of times and make sure I really need to be doing that.
There's always the reflection option. Something substantially similar to this:
public static void Copy(object source, object target)
{
foreach (System.Reflection.PropertyInfo pi in source.GetType().GetProperties())
{
System.Reflection.PropertyInfo tpi = target.GetType().GetProperty(pi.Name);
if (tpi != null && tpi.PropertyType.IsAssignableFrom(pi.PropertyType))
{
tpi.SetValue(target, pi.GetValue(source, null), null);
}
}
}
Doesn't require the source and the target to have any relation what-so-ever, just a name and an IsAssignable check. It has the interesting side effects if you're using reference types anywhere, but for the kind of situation you just described, this isn't a bad option to explore.
class sourceTester
{
public bool Hello { get; set; }
public string World { get; set; }
public int Foo { get; set; }
public List<object> Bar { get; set; }
}
class targetTester
{
public int Hello {get; set;}
public string World { get; set; }
public double Foo { get; set; }
public List<object> Bar { get; set; }
}
static void Main(string[] args)
{
sourceTester src = new sourceTester {
Hello = true,
World = "Testing",
Foo = 123,
Bar = new List<object>()
};
targetTester tgt = new targetTester();
Copy(src, tgt);
//Immediate Window shows the following:
//tgt.Hello
//0
//tgt.World
//"Testing"
//tgt.Foo
//0.0
//tgt.Bar
//Count = 0
//src.Bar.GetHashCode()
//59129387
//tgt.Bar.GetHashCode()
//59129387
}