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Thanks for your reply. I wrote it to a text file. Now converting this cryptic byte to a form that I can save in a database is the challenge am facing as am writing this this to you.
I will appreciate if you can still help.
Thanks
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Can I write the byte directly to a database.
If yes how.
If no, how can I convert the byte in the file to a form that I can save to the database
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Yes, you can, to a column of type binary or varbinary. The former is used to store fixed length blobs while the latter is used to store blobs of varying length.
/ravi
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code for how to check if a file is encrypted in c#
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It is not really possible to tell if it's encrypted since, if it is done properly, there is not information in the file about the encryption method or keys. And a file is just a stream of bytes, so an encrypted file looks just the same as an unencrypted one.
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I've got an WPF application (without MVVM or similar), using EF6 (via a OData Webservice) and I wondering whats the best place to update some 'audit' fields.
i.e. one entity looks like
public class ActionStatus
{
public int Id {get;set;}
public string ActionStatus{get;set;}
[DataType(DataType.Date)]
public DateTime ValidFrom { get; set; }
[DataType(DataType.Date)]
public DateTime ValidTo { get; set; }
public string ChangedBy { get; set; }
public DateTime ChangedOn { get; set; }
}
So on the WPF side I've got this displayed in a DataGrid, which saves the data back etc, all good so far.
For the ChangedBy and ChangedOn fields I want the 'system' to update these as required.
But I'm not sure where it would go!
Doing it on the DataGrid events, seems very wrong...far too late, and would need to be done differently if I didn't use a datagrid in the future.
The other places, are the OData WebService, the EF Model, or in the entities themselves, or maybe as another part of the 'system', not sure...
I presume that this is one of the 'lots of solutions/it depends' type of problems, but some guidance would be helpful.
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That's not an audit-trail, but an indication who made the last change. It'd be an audit if it is a complete trace.
cjb110 wrote: .far too late, and would need to be done differently if I didn't use a datagrid in the future.
The database - that way it won't matter whether it's a webservice, a WinForm or any other UI/app reading from the database.
I'd recommend implementing the bare necessities, and nothing more.
Bastard Programmer from Hell 
If you can't read my code, try converting it here[^]
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Eddy Vluggen wrote: That's not an audit-trail, but an indication who made the last change.
heh, I realise, couldn't think of a better term for it.
Eddy Vluggen wrote: The database - that way it won't matter whether it's a webservice, a WinForm or any other UI/app reading from the database.
As EF is 'creating' my database, and with migrations keeping it up to date, does that mean I add it there as C# code?
Or somehow make the migrations side run additional sql to either add trigger or constraint etc?
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cjb110 wrote: run additional sql to either add trigger
That way it would be automagically added/updated whenever someone mutates a record.
Bastard Programmer from Hell
If you can't read my code, try converting it here[^]
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Hello guys. I am trying to do two things with C#.
1- Getting event for pressing and holding the mouse click (left or any click).
2- Disabling left mouse click event for a control.
I have tried different combinations of the existing events but as expected,they didn't work. What could I do to get above two events. Thanks for anything.
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Django_Untaken wrote: I have tried different combinations of the existing events but as expected,they didn't work.
You will need to expand on that and explain what you mean by "as expected,they didn't work". Why would you expect them not to work, and what exactly happens in your code?
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I have a grid with empid's now if a person selects 2 grid by selecting checkboxes and click on download button 2 files should be offered to download.
I know that we can create a file and can send the location of the physical file.
But is there a way i can stream the files
Download button click is via ajax.
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Yep,
public ActionResult GetFile()
{
var theStream = new Memorystream();
return new FileStreamResult(theStream, string appropriateContentType);
}
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Hello. I am using an ActiveX plugin (which is freely available) in .Net to play videos. Now whenever I switch from Code View to Designer View, Visual Studio 2010 crashes and restarts itself. I have tried to start the VS2010 as an administrator but in vain. What could be wrong and what could I try to prevent this? Thanks for any pointer.
This world is going to explode due to international politics, SOON.
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From the point of view of that ActiveX control, its use on a form may look like "run-time" instead of "design-time".
In your code (constructor of the form, InitializeComponent), determine run-time/design-time and set some properties of that control accordingly (is there an Enabled property or something like that?).
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Bernhard Hiller wrote: its use on a form may look like "run-time" instead of "design-time"
I didn't understand it so please elaborate it. And yes, it does have an Enabled property in the InitializeComponent() and it is set to true. I am gonna paste some most importatnt properties here
this.ControlPlayer.Dock = System.Windows.Forms.DockStyle.Fill;
this.ControlPlayer.Enabled = true;
this.ControlPlayer.Location = new System.Drawing.Point(0, 0);
this.ControlPlayer.Name = "ControlPlayer";
this.ControlPlayer.OcxState = ((System.Windows.Forms.AxHost.State(resources.GetObject("ControlPlayer.OcxState")));
this.ControlPlayer.Size = new System.Drawing.Size(409, 317);
this.ControlPlayer.TabIndex = 2;
((System.ComponentModel.ISupportInitialize)(this.ControlPlayer)).EndInit();
This world is going to explode due to international politics, SOON.
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Sort of a different approach, but why not just use a panel in place of the control, and instantiate the control and dock it into the panel explicitly outside the scope of designer code?
This might be a good approach if the control is badly behaved.
Regards,
Rob Philpott.
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So I did some performance testing on Dictionary<K,V> based on different key types (1M iterations):
1) int, string = 10ms
2) Type, string = 20ms
3) string, string = 40ms
4) Tuple<Type, string>, string = 120ms!!!
5) struct, string = 590ms!!!
Right now I'm using #2 in a performance critical loop... but I really need something like #4, but the performance overhead is just not acceptable.
Anybody got any ideas for a multi-key dictionary that isn't going to kill my performance?
My only idea so far is to get kinda hacky and go with #3 and append to string & Type.ToString() together. I.e. "Bob;System.Int32".
I'd really like to avoid hackyness though as this is actually code I care about lol  .
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Try implementing your own fast ToHash and Equals methods perhaps
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I tried something like this:
class _Key
{
public string s;
public Type t;
public override int GetHashCode()
{
return s.GetHashCode() ^ t.GetHashCode();
}
public override bool Equals(object obj)
{
_Key o = obj as _Key;
if (o == null)
return false;
if (s == o.s && t == o.t)
return true;
return false;
}
}
and it yielded 60ms. Seems kinda pricey still. Compared to the Type key alone (20ms).
EDIT: tried something else... made the key an int and called GetHashCode() on the object to get the key. That knocked it down to 40ms.
EDIT #2: tried just returning the GetHashCode() on one of the members. Type = 50ms, string = 50ms.
Not really sure of a better way to implement GetHashCode().
Any suggestions?
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If you want your gethashcode method to be faster than the inbuilt one you'll need to
a.) Make sure that collisions are as rare as possible for your specific data, this can be done via implementing a custom hashing algorithm to suit your data
b.) Ensure that GetHashCode is very fast in terms of cycles
Because you're just calling the GetHashCode on string and type above. It's going to be no faster or better than the inbuilt ones.
You'll need to come up with a hashing scheme that's faster and stronger (Less frequent collisions) than the inbuilt ones.
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You might also want to post the code for your benchmark so we can check if it's valid
It's very easy to mess up tests like this
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I just did:
Dictionary<int, string=""> dict = new Dictionary<int, string="">();
dict[5] = "Test";
DateTime dt = DateTime.Now;
for (int i = 0; i < 1000000; i++)
{
// 10ms - int x string
string s;
dict.TryGetValue(5, out s);
}
System.Diagnostics.Debug.WriteLine((DateTime.Now - dt).TotalMilliseconds);
It's really that simple. I know that's only 1 key, so my mileage may vary with a bunch of keys. I tried that same thing with various types to get the benchmarks I originally posted.
HOWEVER, I had a brilliant break through haha. Would something like this work?
Dictionary<int, string=""> dict;
struct _Key
{
Type type;
string str;
}
Now, instead of overriding the GetHashCode and IsEquals, I just have a method:
public int GetKey(string s, Type t)
{
return s.GetHashCode() ^ t.GetHashCode();
}
whenever I want to insert a new object, I call GetKey() on it and use that as the key?
As I'm typing this, I'm beginning to poke holes in this idea... there would be no way to retrieve the string and type as I would just be keying off the hash code.
I'm also wondering if it would be possible to get two s and t combinations that produce the same key? Theoretically, I'm assuming the .net hash functions are strong. Although since I wouldn't be inserting the _Key struct into the list (and thus not override the IsEqual(), the dictionary wouldn't know for sure it was grabbing the right one...
If I do it "right" and insert the _Key, that's 60ms... better then 120ms or 590ms I guess.
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It will probably be difficult to beat the inbuilt hash code functions for the general case
however there might be something about your specific data that you can exploit to make a stronger hash function
Example: If you know the first 4 chars of your strings are nearly always unique, you could just turn those into the 32 bit hash. This would save .NET framework from hashing the entire string so it will be faster.
It will also be stronger because you used knowledge specific to your data (Eg, the first 4 chars are enough)
If there are any features of your keys like above you can exploit. The chances of doing better than the inbuilt stuff will be much better
Cheers
Matt
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