Re: Invalid Argument in For Loop - C# Discussion Boards

computerpublic2-Mar-14 8:33

2-Mar-14 8:33

I changed it to an int and I still get an error.

Eddy Vluggen2-Mar-14 9:04

Eddy Vluggen

2-Mar-14 9:04

The same one or a new one?

Bastard Programmer from Hell Suspicious | :suss:

If you can't read my code, try converting it here[^]

Message Closed

2-Mar-14 9:17

2-Mar-14 9:17

Message Closed

Richard MacCutchan2-Mar-14 22:43

2-Mar-14 22:43

He did not insult you, he asked you a perfectly reasonable question. You have stated that you get an error, but you have given no details of what that error is. Is it "invalid argument", and if so on what line of code. If it is something different then show the details. But in either case please be clear what the problem is and where it occurs, and people will try to help you. But if you resort to insults and rudeness you are likely to get no help at all.

noone24072-Mar-14 17:46

noone2407

2-Mar-14 17:46

Can you comment all your code?
Then I will fix it for you.
PS: always check variable is null or not, if you are not sure before calling it

computerpublic2-Mar-14 18:00

2-Mar-14 18:00

<pre>
using System;
using System.IO;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Boolean;
 
namespace Applica
{
    class Program
    {
        static void Main(string[] args)
        {
            DirectoryInfo da = new DirectoryInfo("C:\\Folder9");
            FileInfo[] Arr = da.GetFiles();
            FileInfo ap = Arr[Arr.Length - 1];
            long Totbyte = ap.Length;//file length
            string filePath = ap.FullName;//file name
            string temPath = Path.GetTempFileName();//path
            byte[] data = File.ReadAllBytes(filePath);//reading entire file
            File.WriteAllBytes(temPath, data);       //writing entire file to byte array     
            byte[] dataB = new byte[1];//declaring a one element byte array
            BitArray bits = new BitArray(dataB);//moving one byte to a bit array (8 bits)
            for (uint counter = 0; counter < Totbyte; counter++)
            {
                dataB[0] = data[counter];//moving data one byte at time.
                for (uint count = 0; count < bits.Length; count++)//looking at each bit of each byte
                {
                    if (bits[count] == 0)//PROBLEM AREA
                        Console.Write(bits[count] ? "1" : "0");
                }
            }
        }
    }
}

noone24072-Mar-14 18:32

noone2407

2-Mar-14 18:32

I don't understand what you are trying to do.
But if you want to write out the byte array of the file then here is the code

DirectoryInfo da = new DirectoryInfo("C:\\Folder9");
FileInfo[] Arr = da.GetFiles();
FileInfo ap = Arr[Arr.Length - 1];
long Totbyte = ap.Length;//file length
string filePath = ap.FullName;//file name
byte[] data = File.ReadAllBytes(filePath);//reading entire file
for (int counter = 0; counter < Totbyte; counter++)
{
    Console.Write(data[counter]);
}

Remember that is byte array, not bit array
If you to write out bit array instead of byte array, replace

Console.Write(data[counter]);

Into

string yourByteString = Convert.ToString(data[counter], 2).PadLeft(8, '0');
Console.Write(yourByteString+" ");

modified 3-Mar-14 0:40am.

OriginalGriff2-Mar-14 22:49

OriginalGriff

2-Mar-14 22:49

There are two problems here: firstly that an array index needs to be an integer - and a uint needs an explicit cast to int - you can't use an implicit cast because it could "throw away" data in the form of positive values with the top bit set. Easiest solution: use int value in your for loop.

The second problem is that the BitArray indexer does not return an int value: it returns a bool. So if you correct the first error, the compiler will complain that it cannot compare an int with a bool!

Those are easily fixed to let your program compile:

for (int counter = 0; counter < Totbyte; counter++)
    {
    dataB[0] = data[counter];
    for (int count = 0; count < bits.Length; count++)
        {
        if (!bits[count])
            Console.Write(bits[count] ? "1" : "0");
        }
    }

But... It's not going to work.
You don't change the value in Bits at all inside your outer loop - so each byte "value" is going to print as the same sequence of bits.

Personally, I wouldn't use a BitArray - it's an unnecessary complication here - just use the C# standard bit manipulation operators:

for (int counter = 0; counter < Totbyte; counter++)
    {
    int b = (int) data[counter];
    for (int count = 0; count < 8; count++)
        {
            Console.Write(b & 1);
            b = b >> 1;
        }
    }

Those who fail to learn history are doomed to repeat it. --- George Santayana (December 16, 1863 – September 26, 1952)
Those who fail to clear history are doomed to explain it. --- OriginalGriff (February 24, 1959 – ∞)

computerpublic3-Mar-14 3:52

3-Mar-14 3:52

I only need to evaluate if whether or not a "0" exist in the BitArray string. I dont care about the "1".

OriginalGriff3-Mar-14 4:30

OriginalGriff

3-Mar-14 4:30

And what are you going to do if it is a one? now print anything? Laugh | :laugh:

Trust me: AND the value with 1 returns either 0 or 1 depending on the state of teh least significant bit the in value. Using >> then shifts the whole input down a single bit, so the second bit takes the place of first, and so forth. It's a lot more efficient than using a BitString for each byte.

Richard MacCutchan2-Mar-14 22:54

2-Mar-14 22:54

You cannot use an unsigned as an index, it must be signed. And you cannot compare a bit with the integer value zero. A bit can only be true or false. Change the loop code to

for (int count = 0; count < bits.Length; count++)
{
    if (bits[count])
        Console.Write(bits[count] ? "1" : "0");
}

computerpublic3-Mar-14 3:53

3-Mar-14 3:53

I only need to evaluate if whether or not a "0" exist in the BitArray string. I dont care about the "1".

Richard MacCutchan3-Mar-14 4:11

3-Mar-14 4:11

Then just test for false; the BitArray[item] is a boolean value.

computerpublic3-Mar-14 4:16

3-Mar-14 4:16

Should it be:
bool a = false;
a=bits[count];
if (a)
{
}
is this correct?

Richard MacCutchan3-Mar-14 4:22

3-Mar-14 4:22

No, you should just be testing the specific bit:

if (!bits[count])
// OR
if (bits[count] == false)

However, having looked more closely at your code I am at a loss to understand what the program is supposed to do. In particular why you are reading those files and why you are writing new copies of them, or what any of that has to do with your for loops.

computerpublic3-Mar-14 7:39

3-Mar-14 7:39

<pre>/*No more errors. My input to the program is letter "e" which is enclosed within a text file in c:\\folder9. The decimal equivalent of letter "e" is 101. When I run 101 thru the BitArray, it evaluates all bits as false which is NOT CORRECT.*/
using System;
using System.IO;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Applica
{
    class Program
    {
        static void Main(string[] args)
        {
            DirectoryInfo da = new DirectoryInfo("C:\\Folder9");
            FileInfo[] Arr = da.GetFiles();
            if (Arr.Length == 0)
            {
                throw new InvalidOperationException("No files found.");
            }
            // No need to loop through the array just to get the last item:
            FileInfo ap = Arr[Arr.Length - 1];
            long Totbyte = ap.Length;
            string filePath = ap.FullName;
            Console.WriteLine("Total Bytes = {0} bytes", Totbyte);
            // GetTempFileName *creates* the file, so it always exists:
            string temPath = Path.GetTempFileName();
            byte[] data = File.ReadAllBytes(filePath);
            File.WriteAllBytes(temPath, data);            
            
            byte[] dataB = new byte[1];
            BitArray bits = new BitArray(dataB);
            Console.WriteLine("length= {0}",bits.Length);
            for (long counter = 0; counter < Totbyte; counter++)
            {
                dataB[0] = data[counter];
                Console.WriteLine("{0}", dataB[0]);
                for (int count = 0; count < bits.Length; count++)
                {
                    if (bits[count] == true)
                        Console.WriteLine("{0}", bits[count]);
                    if (bits[count] == false)
                        Console.WriteLine("{0}", bits[count]);
                }
            }
        }
    }
}

Richard MacCutchan3-Mar-14 21:59

3-Mar-14 21:59

computerpublic wrote:
When I run 101 thru the BitArray, it evaluates all bits as false which is NOT CORRECT

But the problem is that you do not run that value through it. Your code is:

byte[] dataB = new byte[1];
// set bits to the content of dataB, which is null at this point
BitArray bits = new BitArray(dataB);
Console.WriteLine("length= {0}",bits.Length);
for (long counter = 0; counter < Totbyte; counter++)
{
    dataB[0] = data[counter];
    Console.WriteLine("{0}", dataB[0]);
    // bits still does not contain any value
    for (int count = 0; count < bits.Length; count++)
    {
        // this can be simplified
        if (bits[count] == true)
            Console.WriteLine("{0}", bits[count]);
        if (bits[count] == false)
            Console.WriteLine("{0}", bits[count]);
    }
}

It should be

byte[] dataB = new byte[1];
for (long counter = 0; counter < Totbyte; counter++)
{
    dataB[0] = data[counter];
    BitArray bits = new BitArray(dataB);
    Console.WriteLine("length= {0}",bits.Length);
    Console.WriteLine("{0}", dataB[0]);
    for (int count = 0; count < bits.Length; count++)
    {
        Console.Write(bits[count] ? "1" : "0");
    }
    Console.WriteLine("");
}

computerpublic4-Mar-14 3:55

4-Mar-14 3:55

I am noticing that the programs default operation is to evaluate the Most Significant Bit First and it evaluates the Least Significant Bit Last. I was not expecting this behavior. This this always the case the default case? Can I change the default operation to do LSB to MSB?

Richard MacCutchan4-Mar-14 5:25