Web Development

24-Sep-07 5:20

I'm converting some code from PHP to C# (.Net 2.0). Can someone that knows PHP verify that the C# code I wrote does the same thing as the original PHP code? The actual line I'm concerned about is inside the for loop.

private string HexToBin(string data) 
{
/*
    // original php function
    $len = strlen($data);
    $newdata='';
    for($i=0;$i<$len;$i+=2) 
    {
        $newdata .=  pack("C",hexdec(substr($data,$i,2)));
    }
    return $newdata;
*/
    int length = data.Length;
    string newData = "";
    for (int i = 0; i < data.Length; i += 2) 
    {
        string value = data.Substring(i, 2);
        newData += Int32.Parse(value, NumberStyles.HexNumber).ToString();
    }
    return newData;
}

Maybe that line in the for loop needs to be this?

newData += string.Format("{0}", Int32.Parse(value, NumberStyles.Integer));

If I completely mangled it up, don't be shy about telling me, but give me the correct code if you feel up to it.

-- modified at 11:50 Monday 24th September, 2007

"Why don't you tie a kerosene-soaked rag around your ankles so the ants won't climb up and eat your candy ass..." - Dale Earnhardt, 1997
-----
"...the staggering layers of obscenity in your statement make it a work of art on so many levels." - Jason Jystad, 10/26/2001

Guffa24-Sep-07 7:34

24-Sep-07 7:34

You can't write a .NET function that does the same as that PHP code, as there are no binary strings in .NET. A PHP character is an eight bit value, while a .NET character is a 16 bit unicode character.

Binary data in .NET is usually represented as a byte array:

private byte[] HexToBin(string data) {
    int length = data.Length / 2;
    byte[] newData = new byte[length];
    for (int i = 0; i < length; i++) {
        string value = data.Substring(i * 2, 2);
        newData[i] = Byte.Parse(value, NumberStyles.HexNumber);
    }
    return newData;
}

---
single minded; short sighted; long gone;

#realJSOP24-Sep-07 9:55

24-Sep-07 9:55

Actually - I can:

private string HexToBin
{
    string newData = "";
    if (data != "")
    {
        for (int i = 0; i < data.Length; i += 2)
        {
            string hexValue = data.Substring(i, 2);

            // either of the next two lines work

            string binValue = string.Format("{0}", <code>Int32</code>.Parse(hexValue, NumberStyles.AllowHexSpecifier));
            // - or -
            //string binValue = string.Format("{0}", <code>Byte</code>.Parse(hexValue, NumberStyles.HexNumber));
            newData += binValue;
        }
    }
    return newData;
}

Guffa24-Sep-07 10:29

24-Sep-07 10:29

John Simmons / outlaw programmer wrote:
either of the next two lines work

That depends on what you mean by "work". They both do something, and the result is the same in both cases, but neither of them produce a result that is useful in any way.

If you have a string containing hexadecimal values, like "07FF10", that code will produce a string containing "725516". That's not a binary string as all, it's just a string containing the digits from the decimal representation of the hexadecimal values. It can't be used for anything at all, not even reproducing the hexadecimal string, as is't impossible to determine where one value ends and the next one begins.

---
single minded; short sighted; long gone;

#realJSOP25-Sep-07 0:14

25-Sep-07 0:14

Guffa wrote:
That depends on what you mean by "work". They both do something, and the result is the same in both cases, but neither of them produce a result that is useful in any way.

The original question was regarding the similarity in functionality, not what the result is to be used for. So back to the original intent - does the C# version do the same thing as the PHP version?

Guffa25-Sep-07 0:25

Re: Converting a PHP HexToBin function to C# [SOLVED]

25-Sep-07 0:25

John Simmons / outlaw programmer wrote:
The original question was regarding the similarity in functionality, not what the result is to be used for. So back to the original intent - does the C# version do the same thing as the PHP version?

No, they don't, as they can't. As I explained, strings doesn't work the same in .NET as in PHP, so there is no .NET equivalent of the PHP binary string.

If you want to work with binary data in .NET you use a byte array instead.

If the binary data represents encoded text, you use one of the Encoding classes to decode the data back to a string. If the binary data for example is text encoded as UTF-8, you use the Encoding.UTF8.GetString method to decode the byte array into a string.

---
single minded; short sighted; long gone;

#realJSOP25-Sep-07 3:37

Re: Converting a PHP HexToBin function to C# [SOLVED]

25-Sep-07 3:37

I finally got a chance to try this at home, and here's the C# version of the PHP code posted in the original message:

private string HexToBin(string data) 
{
    string newData = "";
    if (data != "")
    {
        for (int i = 0; i < data.Length; i += 2)
        {
            string hexValue = data.Substring(i, 2);
            newData += Convert.ToChar(Byte.Parse(hexValue, NumberStyles.HexNumber));
        }
    }
    return newData;
}

Guffa25-Sep-07 19:49