|
So, I'm very very new to C# and programming, but doing some experiments on my own. I created a Database with 3 tables: Student_table: Student_ID, Name, Surname; Course_table: Course_ID, CourseName; Student_Course_table: Student_ID, Course_ID. There is a relationship between them. Database part I'm OK.
Now on C# I created 2 forms. 1 Form fills the Course_table. The other Form fills the Student_table, but I have a combobox in the Student Form that lists the CourseName, reading from the Course_Table. I want that when the SAVE button is selected, the Student_Course_table is filled using the Student_ID and the Course_ID according to what course the user choose from the drop-down. I can fill the Student_ID in the Student_Course_table but don't know how to fill the Course_ID....any help please? Thanks.
|
|
|
|
|
This is going to sound complicated, but it isn't, not really.
Create a Course Class, and give it two properties ID, and Description
public class Course
{
public int ID {get; set;}
public string Description {get; set;}
}And fill out a collection (a List<Course> will do nicely, or an array, at a pinch) to hold each separate course as you fetch them from the Courses table.
Now add an override method to your new class:
public class Course
{
public int ID { get; set; }
public string Description { get; set; }
public override string ToString()
{
return Description;
}
}
And use the collection as the DataSource property of your Combobox.
Because you override ToString, the comboBox will display the Text Description for the elements, but the SelectedItem property will return an instance of the Course class.
You have to cast it to use it:
Course selected = (Course)cbReversedItems.SelectedItem;
And you then have access to the Description and ID properties in your code.
Give it a try, it's easier than it sounds!
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
AntiTwitter: @DalekDave is now a follower!
|
|
|
|
|
i have a project to do in encrypting image in c#
put i do not know how to encrypt the pixel of image
any one can help me plz
|
|
|
|
|
|
thnx put i need to encrypt the pixel of image not to hied text in image
i went to do something like this [^]
|
|
|
|
|
That's not simple - or particularly useful!
You can do it, but ... You will need to make sure that it is only ever stored as a non-lossy format image: BMP or PNG are good, JPG is bad. Lossy formats will throw away too much info.
Read the image using LockBits (This will help: Getting RGB array from image in C# - Stack Overflow[^]) encrypt the pixel data, and put it back. Do note that the bitmap data is fixed size: so your encryption must not generate a bigger or smaller output, or the image will not be right (any possibly not reversible).
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
AntiTwitter: @DalekDave is now a follower!
|
|
|
|
|
Thank you so much for your help
put ho how to encrypt the pixel data, and put it back
that my question
|
|
|
|
|
That's totally up to you! That's going to depend on why you are doing this: how much security do you need?
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
AntiTwitter: @DalekDave is now a follower!
|
|
|
|
|
Thanks for your patience to help me
i went to encrypt the by entering a key
and decrypt that image only by using that key
|
|
|
|
|
Yes, I understand that. But the encryption method you use will depend on how secure you want this to be: there are many simple methods that use a key, but which aren't particularly complicated (or secure). It depends what you are planning on doing with the encrypted images how secure you need to get. And the more secure you go, the less likely it is that the encrypted data will be anything like the same size as the original image - which means more complexity, as you have to find a way to "hide" the size info for the original with the encrypted data.
And to be honest, if you want anything with reasonable security, you are doing the wrong thing entirely: encrypting the pixels is like waving a red rag to a bull - you are saying "there is something here I don't want you to look at" and that encourages many to think "Oh yeah? Well let's just see about that..." 
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
AntiTwitter: @DalekDave is now a follower!
|
|
|
|
|
What do you advise me to do to do something like this [^] but it should be secure ؟
|
|
|
|
|
As I said: "how secure?"
Why do you want to do this? That might help my understand how secure you need it.
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
AntiTwitter: @DalekDave is now a follower!
|
|
|
|
|
Sorry but my English is not good enough
I want it for my project in college. I want a program to encrypt the image based on Chaotic MAP
I want it so safe that anyone who does not have the key can not see the picture. Without it the picture will remain like this [^]
I want it in any way I just want to have a key through which I can decrypt again
|
|
|
|
|
|
Yes my friend, that's what I mean
I have read it before and I have infertility information
But I want to implement this in a code in c #
|
|
|
|
|
Quote: I have infertility information
Not at all sure what you mean by that ... I'd run it through Google translate to find out what you said if I was you...
Quote: I want to implement this in a code in c #
Then get on and do it: this is your project and you are expected to code it yourself. You can't expect anyone here to do your project for you and let you hand it in as your own work, that wouldn't be fair at all!
Plus ... you do realize that your tutor knows this site exists, and will know if you did that? And fail you for the course?
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
AntiTwitter: @DalekDave is now a follower!
|
|
|
|
|
i just went example how to do that
|
|
|
|
|
Does the encrypted result have to be another (valid) picture?
If no, then you can encrypt it like you would with any other file, as it is just another collection of bytes.
Bastard Programmer from Hell 
If you can't read my code, try converting it here[^]
|
|
|
|
|
yes i went the image be like this [^]
|
|
|
|
|
If you don't mind your key to be as large as the image itself, you could simply overlay a mask made of noise. Subtract the mask later on to retrieve the image again.
The "one time pad" encryption is explained on Wikipedia.
Bastard Programmer from Hell
If you can't read my code, try converting it here[^]
|
|
|
|
|
no i went to encrypt the each pixel of the image to make the image look like this [^] and decrypt it again
|
|
|
|
|
Works the same way; you fetch a pixel, add a random number and translate that back to a color. For decrypting, subtract that same random number. Would mean that your "key" is as large as the image itself, which may be a bit of a downside.
Bastard Programmer from Hell 
If you can't read my code, try converting it here[^]
|
|
|
|
|
good now how i can do that in C#
can u gave me example for the code
or some open source Project
|
|
|
|
|
The explanation is on the wiki-page for the one time pad; I don't have sample code.
Bastard Programmer from Hell
If you can't read my code, try converting it here[^]
|
|
|
|
|
As you know how the algorithm works now, why don't you write this yourself? What you need to know is, how to read an image, how to create a random number. The rest is just combining this.
This space for rent
|
|
|
|
General 
News 
Suggestion 
Question 
Bug 
Answer 
Joke 
Praise 
Rant 
Admin 
Submit an article or tip
