Invalid Argument in For Loop

[computerpublic]

My error is in the last 2 lines of the code:

bits[count]

[PIEBALDconsult]

An array index has to be an int (or something implicitly convertable to an int). http://msdn.microsoft.com/en-us/library/system.collections.ilist.item(v=vs.110).aspx[^]

This space intentionally left blank.

[computerpublic]

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

[Lost User]

The same one or a new one?

Bastard Programmer from Hell :suss: If you can't read my code, try converting it here[^]

[computerpublic]

Hey Guy (Eddy Vluggen), I am trying to learn how to program and you continually send insults to me. I am asking you nicely to be respectful and don't respond to me. You are obviously a very miserable person who can find nothing better to do than insult people are asking for help. Why are you even in the forum if you contribute no help. Is this the highlight of your day? Dude you must really need a hug.

[noone2407]

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

[computerpublic]

<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");
}
}
}
}
}

[noone2407]

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+" ");

[Lost User]

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.

[OriginalGriff]

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 – ∞)

[Lost User]

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");
}

[computerpublic]

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

[computerpublic]

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

[Lost User]

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

[computerpublic]

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

[Lost User]

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.

[OriginalGriff]

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

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 – ∞)

[computerpublic]

/*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\[count\]);
            }
        }
    }
}

}

[Lost User]

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("");
        }

[computerpublic]

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?