arrays and properties.

dear all,

I have a class called precipitate

class Precipitate
{
private string name;
public string Name
{
get { return name; }
set { name = value; }
}
}

So far so good. I create an array of the precipitate class

Precipitate[] prec = new Precipitate[20];
for (int i = 0; i < 20; i++)
prec Idea

= new Precipitate();

when I want to access the property name for a particular array element we do it as
prec Idea

.name. Again no problem here.

Now I want to have something like...

what I want is something like...
prec Idea

.equation[j].equationname;
prec Idea

.equation[j].valuex;
etc...

how should I do it I just know the basics and dont know if...you can create a property array "equation[]" inside the prec class and make it have properties

I really dont know how to go about it. Any help is appreciated.

cheers
prasad..

Visual C#1

You can use indexer property...

private eqType equation = new eqType[20];
public eqType this [int Index]
{
    {
    get {return equation[index];}
    set {equation[Index] = value;}
    }
}

or public array

public eqType equation = new eqType[20];

ok but how can the equation property array now have
its own properties

like prec Idea

.equation[j].itsname

prasad..

you have to define your class and assign it to array...

class eqType
{
public string equationname;
public string value;
}

public eqType equation = new eqType[20];

this way I will just have another class array called equation[]. and a seperate class called precipitate[].

But as I told in my 1st post, I need to have this equation array as a property in the precipitate class...

to put it in words each precipitate has many equations and each equation has many properties.

hope you understand..

your answer gives me just equation Idea

and precipitate Idea

(seperate array of classes) I want to have precipitate Idea

.equation[j].name etc...

cheers,
prasad..

In that case, you will have a property of generic list or collecion type. Also that list will contain istance of a class that have property equationname and value.
class Equation
{
string _EquationName;
public string EquationName
{
get { return _EquationName; }
set { _EquationName = value; }
}

int _Value;
public int Value
{
get { return _Value; }
set { _Value = value; }
}
}

So the property will be like this:
class Participate
{
......
List<Equation> _Equations;
public List<Equation> Equations
{
get { return _Equations; }
set { _Equations = value; )
}

....
}

So now you can access your generic list of Equation types like this:
prec[ i ].Equations[j].EquationName
prec[ i ].Equations[j].Value

But having collection types properties is not good practice. For that you should use methods. This is just a suggestion that you can think of when you done with this problem.

sorry, I wasn't enough clear...

class precipitate
{
public eqaution[] eq = new equation[20]
}

class equation
{
public string equationname;
public string value;
}

void main
{
precipitate[] p = new precipitate[10];

Debug.WriteLine(p[2].eq[1].equationname);
}

thanks a ton that worked nicely.
BTW, can you please tell me why it is bad to use them and how at all methods can be used to do the same thing

Thank you again for the nice help.
cheers,
prasad..

Here are some infos about this:
http://msdnwiki.microsoft.com/en-us/mtpswiki/0fss9skc(VS.80).aspx and
http://msdnwiki.microsoft.com/en-us/mtpswiki/26967aaf-6fbe-438a-b4d3-ac579b5dc0f9.aspx

how to initialise the list
If I do it the following way,

Equation[] myequation = new Equation Music

;

for(i=0;i<8;i++)
myequation Idea

= new Equation[];

it gives me null reference error.

should we do..
for(j=0;j<something<j++)
for(i=0;i<8;i++)
precipitate[j].myequation Idea

= new Equation[];

cheers,
prasad..

class Precipitate
{
private equation[] ex; // Initialize in ctor
public equation[] equation
{
get { return ex; } // just a getter. A setting is unecessary and will cause trouble.
}
}

So, now...

Precipitate p = new Precipitate();
p.equation is an array of equations and

p.equation[ i ] is one element of that array.

p.equation[ i ].equationname is a property of that one element of that array.

I am getting a null reference exception, please help.

code

Precipitate[] prec = new Precipitate[30];
for (int i = 0; i < 30; i++)
prec Idea

= new Precipitate();

FerEqn[] FerriteEquation = new FerEqn Music

;
for (int i = 0; i < totalPrecsConsidered; i++)
{
for (int j = 0; j < 8; j++)
{
prec Idea

.FerriteEquation[j] = new FerEqn();
}
}

class Precipitate
{
List<FerEqn> ferriteEquation;

internal List<FerEqn> FerriteEquation
{
get { return ferriteEquation; }
set { ferriteEquation = value; }
}

class FerEqn
{
string authName;

public int AuthName
{
get { return authName; }
set { authName = value; }
}
}

when I try p[0].FerriteEquation[0].AuthName = "Something";

it gives me a null reference exception

Many thanks in advance,
prasad..

You missed an important line in you message : // Initialize in ctor

So, let's see if you can fix this:

class FerEqn
        {
        string authName;

        public int AuthName
            {
            get { return authName; }
            set { authName = value; }
            }
     }

This is fine.

but the the array (Well, now list) of FerEqn is defined inside Precipitate, and should be initialized inside Precipitate

class Precipitate
        {
           List<FerEqn> ferriteEquation;
        public List<FerEqn> FerriteEquation
            {
            get { return ferriteEquation; }
            set { ferriteEquation = value; }
            }

        public Precipitate()
        {
            const int numEqu = 8;
             ferriteEquation = new List<FerEqn>(numEqu);
             // SInce you apparently want to immedately use indexer access to the list,
             // we'll have to put some items in the list.
            for (int i = 0; i < numEqu; ++i)
                  ferriteEquation.Add(new FerEqu());
        }
}