How to solve Check array index and length?

Question

Error message: System.ArgumentException: 'Destination array is not long enough to copy all the items in the collection. Check array index and length.'

public static string PassConv(string Password)
{
    int iLoop;
    int iL;
    int iTotal;
    int iValue;
    string sPassConv;

    iL = 3;
    iTotal = 0;

    for (iLoop = 1; iLoop <= Password.Length; iLoop++) {

        string sNo = Password.Substring(iLoop-1,1);

        byte[] asciiBytes = Encoding.ASCII.GetBytes(sNo);

        iValue = BitConverter.ToInt32(asciiBytes, 0); ---->**Error**

        iTotal = iTotal + iValue * (iL + iLoop - 1);  

        sPassConv = iTotal.ToString();

    }
    return sPassConv;
}

Please Help Thank

What on Earth are you trying to do here? At the moment you're taking a single character from a string (`Password`), encoding that to bytes with ASCII encoding, and then trying to treat that byte data as a 4-byte binary value containing an integer. Since you're using ASCII, I'd expect that the length of `asciiBytes` will likely always be 1. — ProgrammingLlama, Feb 21 '20 at 02:56
I'm assuming you really want [this](https://stackoverflow.com/questions/1019793/how-can-i-convert-string-to-int)? — ProgrammingLlama, Feb 21 '20 at 02:58
Ah, you seem to want [this](https://stackoverflow.com/questions/43370754/how-to-get-ascii-value-of-characters-in-c-sharp). — ProgrammingLlama, Feb 21 '20 at 04:05

Tấn Nguyên · Accepted Answer · 2020-02-21T06:32:56.950

I try to reach your idea because of so many redundancy codes. By using:

SubString exports each character even Encoding.ASCII.GetBytes can return all byte array from these characters
BitConverter expected of 4-byte binary input as well https://learn.microsoft.com/en-us/dotnet/api/system.bitconverter.toint32 and seem this function is no help at all
Declare iLoop = 1 but inside loop does iLoop - 1
sPassConv gets value from iTotal so many times, should put outside the loop

Quick fix from your code:

public static string PassConv(string Password)
{
    int iLoop;
    int iL;
    int iTotal;
    int iValue;
    string sPassConv = "";

    iL = 3;
    iTotal = 0;

    for (iLoop = 1; iLoop <= Password.Length; iLoop++)
    {

        string sNo = Password.Substring(iLoop - 1, 1);

        iValue = Encoding.ASCII.GetBytes(sNo)[0];

        iTotal = iTotal + iValue * (iL + iLoop - 1);

        sPassConv = iTotal.ToString();

    }
    return sPassConv;
}

A little bit refactor

public static string PassConv2(string Password, int iL = 3)
{
    int iTotal = 0;

    var bytes = Encoding.ASCII.GetBytes(Password);

    for (var iLoop = 0; iLoop < bytes.Length; iLoop++)
    {
        // bytes[iLoop] = iValue
        iTotal += bytes[iLoop] * (iL + iLoop);
    }
    return iTotal.ToString();
}

This function is need to be improved because it does loop 2 times, first to bytes and second to calculate. Since every character can convert to ASCII even Extended ASCII, so we could cast it directly. PassConv3 gives more exact when input is Unicode such as "Áaa", the Encoding.ASCII.GetByteswill cast as "?aa" with '?' represents 63 ASCII

public static string PassConv3(string Password, int iL = 3)
{
    int iTotal = 0;

    for (var iLoop = 0; iLoop < Password.Length; iLoop++)
    {
        iTotal += Password[iLoop] * (iL + iLoop);
    }
    return iTotal.ToString();
}

And the result

public static void MainFunc()
{
    Console.WriteLine(PassConv("ABCD")); // 1202
    Console.WriteLine(PassConv2("ABCD")); // 1202
    Console.WriteLine(PassConv3("ABCD")); // 1202
}

Hope it helps !

How to solve Check array index and length?

1 Answers1