Differance Between Protected and protected internal - C# Discussion Boards

25-Jun-07 0:26

How can I get to see the values coming into LPT1 378H? Is there a general method belonging to a class to call?

Thanks

Samuel

Hesham Yassin25-Jun-07 0:59

Hesham Yassin

25-Jun-07 0:59

of cource, you need to use the dll file inpout32.dll.
[importDll....]

if this is not enough for you, i can send you a code which makes the work.

mercenary0125-Jun-07 1:01

25-Jun-07 1:01

I have the dll file...but I can't figure out how to listen to the port..I have void PortAccess(Address)... why is it void??? how to I read than? the output is ok....but I cannt read the port

Samuel

mercenary0125-Jun-07 1:09

25-Jun-07 1:09

hmmm, I have the following in the class is it correct

public class PortAccess
{
[DllImport("inpout32.dll", EntryPoint="Out32")]
public static extern void Output(int adress, int value);
[DllImport("inpout32.dll", EntryPoint="Inp32")]
public static extern voidInput(int adress);
}

shouldnt the last line be
public static extern int Input(int adress);

Hesham Yassin25-Jun-07 10:05

Hesham Yassin

25-Jun-07 10:05

public class PortAccess
{
[DllImport("inpout32.dll", EntryPoint = "Out32")]
public static extern void Output(int adress, int value);

[DllImport("inpout32.dll", EntryPoint = "Inp32")]
public static extern byte Input(int adress);
} // PortAccess

mercenary0125-Jun-07 15:58

Differance Between Protected and protected internal

25-Jun-07 15:58

Thanks its working now

Rahul.RK24-Jun-07 23:54

Re: Differance Between Protected and protected internal

24-Jun-07 23:54

Hello Friends,

I want to know what is difference between protected and protected internal.

i know that protected means access limited to type and types derived from it.

and protected internal means access limited to type and types derived from it

or in the assembly.

Do protected is subset of protected internal. And do protected is required when

we specify internal as access specifier.

please give example that will be helpfull..

Thanks in advance.

rahul kulkarni

Colin Angus Mackay25-Jun-07 0:00

Re: Differance Between Protected and protected internal

25-Jun-07 0:00

Rahul.RK wrote:
I want to know what is difference between protected and protected internal.

According to the documentation[^] the answer is:

protected = Access is limited to the containing class or types derived from the containing class
protected internal = Access is limited to the current assembly or types derived from the containing class

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Rahul.RK25-Jun-07 0:05

Re: Differance Between Protected and protected internal

25-Jun-07 0:05

hello Thanks for reply...

i got the concept according to definition.

But as internal gives access to all the assembly then

what is use of protected?

Thats my question..

Rahul Kulkarni

Colin Angus Mackay25-Jun-07 0:09

Re: Differance Between Protected and protected internal

25-Jun-07 0:09

Rahul.RK wrote:
But as internal gives access to all the assembly then what is use of protected?

So you can derive a class from it from outside the assembly.

Rahul.RK25-Jun-07 0:18

Re: Differance Between Protected and protected internal

25-Jun-07 0:18

Thanks alot....

Will you please give me any helpfull site of book name

which will give me idea of all this basic fundamentals of C#.Net

Rahul Kulkarni

Colin Angus Mackay25-Jun-07 0:23

Re: Differance Between Protected and protected internal

25-Jun-07 0:23

There are lots of beginner books. It really depends on your style of learning. Go to the book store and browse through a few books. Pick the one that appeals to you most.

Rahul.RK25-Jun-07 0:25

25-Jun-07 0:25

Thanks for help.

Rahul Kulkarni

DBNull.Value problem

t4ure4n24-Jun-07 23:46

24-Jun-07 23:46

Hello i am facing a slight problem with Store a record in the database.

I have a column of Type Decimal (It can have null values in the DB).
i take the input in a textbox and saves it to the database.

dataRow["SPEED"] = (this.tbSpeed.Text == "" ? DBNull.Value.ToString() : this.tbSpeed.Text);

If I leave it blank it gives me following error

An unhandled exception of type 'System.ArgumentException' occurred in System.Data.dll

Additional information: Input string was not in a correct format.Couldn't store <> in SPEED Column. Expected type is Decimal

What could be the solution to this problem

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Colin Angus Mackay24-Jun-07 23:55

24-Jun-07 23:55

t4urean wrote:
DBNull.Value.ToString()

Why are you suppling a ToString() on DBNull.Value? Don't do that just pass DBNull.Value

t4ure4n24-Jun-07 23:57

24-Jun-07 23:57

If I don't use DbNull.value.tostring() then i get the following error

Type of conditional expression cannot be determined because there is no implicit conversion between 'System.DBNull' and 'string'

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Colin Angus Mackay25-Jun-07 0:03

25-Jun-07 0:03

I suspect that is because of the trinary operator that you are using. These are generally considered to be bad practice.

Try this:

if (this.tbSpeed.Text == "")
     dataRow["SPEED"] = DBNull.Value;
else
     dataRow["SPEED"]  = this.tbSpeed.Text;

Colin Angus Mackay25-Jun-07 0:04

25-Jun-07 0:04

And I'd guess that that the contents of the text box will need to be converted to a decimal also.

martin_hughes25-Jun-07 1:07

martin_hughes

25-Jun-07 1:07

Try this:

dataRow["Speed"] = this.tbSpeed.Text ?? (object) DBNull.Value;

blackjack215025-Jun-07 0:20

blackjack2150

25-Jun-07 0:20

IF you would use a simple "IF", it would be very simple.

t4ure4n25-Jun-07 0:25

25-Jun-07 0:25

I have used this even then i am getting the same error

if (this.tbSpeed.Text == "")
dataRow["SPEED"] = DBNull.Value;//"NULL";
else
dataRow["SPEED"] = this.tbSpeed.Text;

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blackjack215025-Jun-07 0:51

blackjack2150

25-Jun-07 0:51

Your manner of storing values in the database seems pretty unusual. I would create a command with an "INSERT" statement as the command text and call it's ExecuteNonQuery() method. For the decimal column I would use an SQL Parameter of decimal type to avoid format errors.

t4ure4n25-Jun-07 0:56