Cystal Report Chart questions-C# Winforms using cystal report - C# Discussion Boards

Cystal Report Chart questions-C# Winforms using cystal report

29-Jun-04 14:11

Something obviously is stored in that class that you're not saving (perhaps the key, which in these snippets is getting created each time, even between encryption and decryption calls).

How are you saving the ciphertext across calls and instances of the containing class? Are you writing them to a file? If you use a TextWriter, you may be inadvertently writing a BOM (byte order mark) to the beginning of the file. Depending on how you read the file back in, this BOM may become part of the ciphertext (a TextReader should strip this, but if you use a FileStream or something, it won't be stripped from the rest of the ciphertext, for example).

The only thing with block ciphers is, though, that if something is screwed up then the ciphertext would be invalid. The only possibility for this not to happen as I see it is if a particular block of ciphertext were changed and the block data size wasn't changed, and this may only work (depending on the algorithm) if the data wasn't signed, either (because the digest would be invalid). If this is possible (depending on the algorithm), then the rest of the blocks should decrypt.

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Re: Encryption problems

Not Active29-Jun-04 16:16

Not Active

29-Jun-04 16:16

Thanks Heath, I found the error. The key being used was the same for encryption and decryption but I was generating the initalization vector each time ( GenerateIV() ). After I made sure to use the same for each way it works fine. Doh!!

Anonymous29-Jun-04 9:40

Anonymous

29-Jun-04 9:40

1.Is there anyway, when selecting a chart in a report, to have it enlarged on the next page automatically such as 150% bigger?

2. The Y axis of the graph gets cut off if it has a too large number.(start from Zero). How to enlarge the margin to show the whole number? And how can I put a number starts from ( if not from Zero) and how can I define an increment step by my own?

3.To show a summary of a report field in a chart, it will show 'Sum of TableName.FieldName' Format in the legent. I want to customize a name for the summary such as 'Total Sales' instead of ' Sum of SalesTable.SalesPerMonth ',
I have tried to define a custom field to hold the summary resault, but the chart is showing @TotalSale. with '@' in legent.
How can I customize a name for the legend?

Thanks in advance.

C# missing anonymous classes?

vista2729-Jun-04 8:39

vista27

29-Jun-04 8:39

so i finally came across a situation today that i thought would be ideal if i were able to implement an anonymous class on the fly like you can in java. by default, ComboBoxes use the ToString() method as the listed label when you add an item to it. So if you create a new object, add it to the comboBox, it will be listed as a "System.Object". What I wanted to do was to simply add an object for only one purpose, to list itself as "ALL". So I created a class just so I can override the ToString() to return "ALL" and passed it into the Items.Add(). it would have been nice to do it like in java like so:

ComboBox.Items.Add(new object(){
public override string ToString(){
return "ALL";
}
})

but u can't do that in C#. Smile | :)

any comments?

Judah Gabriel Himango29-Jun-04 8:49

Judah Gabriel Himango

29-Jun-04 8:49

Unless I'm misunderstanding, C# provides a much more elegant way to do this:

ComboBox.Items.Add("ALL");

#include "witty_sig.h"

vista2729-Jun-04 9:22

vista27

29-Jun-04 9:22

haha, OK, i agree, your way is a tad more elegant.

but ok, for the sake of argument, what IF there were no overloaded version that took a string argument, and internally the ony way to make the display change was to alter the ToString() method. and maybe you want to add a few things to the class and don't need to save references to the objects. THEN wouldn't it be nice to have anonymouse classes? Smile | :)

Judah Gabriel Himango29-Jun-04 9:45

Judah Gabriel Himango

29-Jun-04 9:45

Actually it's not an overloaded method. All types in the .NET BCL (pointers aside) inherit from System.Object. Since a the listbox wants an object, you can pass literally anything into it, an int, string, bool, whatever.

Now as for anonymous classes, the case you're making for is anonymous objects. To me I don't see a real need; you're defining and instanciating an object in place -- if you really need to instanciate with custom data just use a regular class; less clutter and more concise code that way IMO. But maybe that's just me. Smile | :)

#include "witty_sig.h"

Heath Stewart29-Jun-04 9:05

29-Jun-04 9:05

And why would you want to? As Judah humorously pointed out, there's a much more elegant way of doing it.

C# 2.0 will, however, allow something similar in fashion for delegates. So instead of having to define a method in order to use a delegate (event handler, callback, etc.), you can define it inline, similar to anonymous definitions like you find in Java.

There's things that C# and .NET in general have that Java can't do similarily as well. To each his own.

Microsoft MVP, Visual C#
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memcmp in C#

BrcKcc29-Jun-04 8:29

29-Jun-04 8:29

I want to compare two byte buffer quickly. I used to do this with memcmp in C. I can't find a function to do that in C#.

I'm sure there is one, but I can't find it.

BRCKCC

Heath Stewart29-Jun-04 9:45

29-Jun-04 9:45

There really isn't a way as fast as memcmp, so if you need that kind of performance, you can always P/Invoke it:

using System;
using System.Runtime.InteropServices;

class Test
{
  static void Main()
  {
    byte[] b1 = new byte[10];
    byte[] b2 = new byte[10];

    for (int i=0; i<b1.Length; i++)
      b1[i] = b2[i] = Convert.ToByte(i);

    Console.WriteLine("Equals:        " + b1.Equals(b2));
    Console.WriteLine("Object.Equals: " + Object.Equals(b1, b2));
    Console.WriteLine("memcmp:        " + Compare(b1, b2));
  }

  static bool Compare(byte[] b1, byte[] b2)
  {
    IntPtr retval = memcmp(b1, b2, new IntPtr(b1.Length));
    return retval == IntPtr.Zero;
  }

  [DllImport("msvcrt.dll")]
  static extern IntPtr memcmp(byte[] b1, byte[] b2, IntPtr count);
}

This would print:

Equals:        False
Object.Equals: False
memcmp:        True

By doing this you sacrific portability, however. If you don't need that kind of performance, use a simple for (not foreach, which is slower) loop and compare each byte using the == equivalency operator.

Microsoft MVP, Visual C#
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BrcKcc29-Jun-04 9:54

29-Jun-04 9:54

I'm using the for loop and since I don't want to sacrifice portability, I'll stick with the for loop.

Thanks.
- Bruce

BRCKCC

Werdna30-Jun-04 5:53

Werdna

30-Jun-04 5:53

Also, if you'd be allowed to use unsafe code, it would be much faster. You'd be able to loop thru the array cast to array of ints and comparing 4 bytes at a time. Plus the CPU works better with int values than single byte values. Of course you'd have to have a special case for padding bytes.

BrcKcc30-Jun-04 6:24

30-Jun-04 6:24

Do you have a snippet of code on how to do this "casting"?

BRCKCC

Werdna30-Jun-04 6:47

Werdna

30-Jun-04 6:47

Here is a simple program that tests the comparison using safe and unsafe version. On my machine the unsafe version is about 4 times as fast as safe version.
You have to make sure you allow unsafe code in project properties.

Note, this will only work with arrays whose size is divisble by 4. You can easily change it to handle the last 1, 2 or 3 bytes specially, but i'll leave it as excercise.

using System;

namespace Tester
{
	class Class1
	{
		[STAThread]
		static void Main(string[] args)
		{
			const int repeats = 200;

			byte[] bytes1 = randomBytes(4 * 1000000);
			byte[] bytes2 = new byte[bytes1.Length];
			for (int i=0; i<bytes1.Length; i++)
				bytes1[i] = bytes2[i];


			// unsafe version
			int start_t = System.Environment.TickCount;
			for (int r=1; r<=repeats; r++)
			{
				bool res = CompareUnsafe(bytes1, bytes2);

				if (r == repeats)
					Console.WriteLine("Result: " + res);
			}
			int end_t = System.Environment.TickCount;
			Console.WriteLine("CompareUnsafe: {0} ms.", (end_t-start_t));

			// safe version
			start_t = System.Environment.TickCount;
			for (int r=1; r<=repeats; r++)
			{
				bool res = CompareSafe(bytes1, bytes2);

				if (r == repeats)
					Console.WriteLine("Result: " + res);
			}
			end_t = System.Environment.TickCount;
			Console.WriteLine("CompareSafe: {0} ms.", (end_t-start_t));
		}

		public static bool CompareSafe(byte[] byteArray1, byte[] byteArray2)
		{
			if (byteArray1.Length != byteArray2.Length)
				return false;

			for (int i=0; i<byteArray1.Length; i++)
				if (byteArray1[i] != byteArray2[i])
					return false;

			return true;
		}

		public unsafe static bool CompareUnsafe(byte[] byteArray1, byte[] byteArray2)
		{
			if (byteArray1.Length != byteArray2.Length)
				return false;

			if (byteArray1.Length % 4 != 0)
				throw new ArgumentException("Byte arrays have to be divisible by 4", "bytearray");

			fixed (byte* bytes1 = &(byteArray1[0]))
			fixed (byte* bytes2 = &(byteArray2[0]))
			{
				int* ints1 = (int*)bytes1;
				int* ints2 = (int*)bytes2;
				int size = byteArray1.Length / 4;
				for (int i=0; i<size; i++)
					if (ints1[i] != ints2[i])
						return false;

			}

			// all comparisons succeeded
			return true;
		}

		public static byte[] randomBytes(int size)
		{
			Random r = new Random();
			byte[] bytes = new byte[size];
			r.NextBytes(bytes);

			return bytes;
		}
	}
}

BrcKcc30-Jun-04 7:02

30-Jun-04 7:02

Thanks very much.
- Bruce
Smile | :)

BRCKCC

Whats an RVA ?

Peter Vertes29-Jun-04 8:27

Peter Vertes

29-Jun-04 8:27

Hi All,

I'm calling an unmanaged function (SetScrollPos()) from my C# code and when I try to instantiate the class that uses this method I get a TypeLoadException with the following message:

Additional information: Could not load type Tradition.TraditionDesktop.TraditionDesktopClient.PageMonitor from assembly PageMonitor, Version=1.0.1641.23960, Culture=neutral, PublicKeyToken=null because the method SetScrollPos has no RVA.

What exactly is an RVA ?

Re: Whats an RVA ?

Peter Vertes29-Jun-04 8:33

Peter Vertes

29-Jun-04 8:33

Nevermind figured it out. I forgot to include the DllImport when I was declaring the method.

Re: Whats an RVA ?

Heath Stewart29-Jun-04 9:49