Convert from string ascii to string Hex

Question

Suppose I have this string

string str = "1234"

I need a function that convert this string to this string:

"0x31 0x32 0x33 0x34"

I searched online and found a lot of similar things, but not an answer to this question.

[Possible duplicate](http://stackoverflow.com/questions/74148/how-to-convert-numbers-between-hexadecimal-and-decimal-in-c): `str.ToString("X");` — mishmash, Apr 10 '13 at 08:32
BTW, your example is not ASCII, .NET strings are Unicode (UTF-16). — Davin Tryon, Apr 10 '13 at 08:35
@vanneto: That won't work. `string` has no overload of `ToString` that takes a parameter of type `string`. — Daniel Hilgarth, Apr 10 '13 at 08:36

score 18 · Accepted Answer · answered Apr 10 '13 at 08:34

string str = "1234";
char[] charValues = str.ToCharArray();
string hexOutput="";
foreach (char _eachChar in charValues )
{
    // Get the integral value of the character.
    int value = Convert.ToInt32(_eachChar);
    // Convert the decimal value to a hexadecimal value in string form.
    hexOutput += String.Format("{0:X}", value);
    // to make output as your eg 
    //  hexOutput +=" "+ String.Format("{0:X}", value);

}

    //here is the HEX hexOutput 
    //use hexOutput

Note that this uses `string` concatenation, which might or might not be a performance problem depending on the size of `str`. — Laurynas Lazauskas, Mar 09 '20 at 19:41

score 11 · Answer 2 · answered Apr 10 '13 at 08:45

This seems the job for an extension method

void Main()
{
    string test = "ABCD1234";
    string result = test.ToHex();
}

public static class StringExtensions
{
    public static string ToHex(this string input)
    {
        StringBuilder sb = new StringBuilder();
        foreach(char c in input)
            sb.AppendFormat("0x{0:X2} ", (int)c);
        return sb.ToString().Trim();
    }
}

A few tips.
Do not use string concatenation. Strings are immutable and thus every time you concatenate a string a new one is created. (Pressure on memory usage and fragmentation) A StringBuilder is generally more efficient for this case.

Strings are array of characters and using a foreach on a string already gives access to the character array

These common codes are well suited for an extension method included in a utility library always available for your projects (code reuse)

score 3 · Answer 3 · answered Dec 31 '15 at 23:35

Convert to byte array and then to hex

        string data = "1234";

        // Convert to byte array
        byte[] retval = System.Text.Encoding.ASCII.GetBytes(data);

        // Convert to hex and add "0x"
        data =  "0x" + BitConverter.ToString(retval).Replace("-", " 0x");

        System.Diagnostics.Debug.WriteLine(data);

Soner Gönül · Answer 4 · 2013-04-10T08:46:14.427

2

static void Main(string[] args)
{
    string str = "1234";
    char[] array = str.ToCharArray();
    string final = "";
    foreach (var i in array)
    {
        string hex = String.Format("{0:X}", Convert.ToInt32(i));
        final += hex.Insert(0, "0X") + " ";       
    }
    final = final.TrimEnd();
    Console.WriteLine(final);
}

Output will be;

0X31 0X32 0X33 0X34

Here is a DEMO.

edited Apr 10 '13 at 08:46

answered Apr 10 '13 at 08:40

Soner Gönül

97,193
102
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364

score 2 · Answer 5 · answered Mar 09 '20 at 19:40

2

A nice declarative way to solve this would be:

var str = "1234"

string.Join(" ", str.Select(c => $"0x{(int)c:X}"))

// Outputs "0x31 0x32 0x33 0x34"

answered Mar 09 '20 at 19:40

Laurynas Lazauskas

2,855
2
21
26

Davut Gürbüz · Answer 6 · 2013-04-10T10:21:36.677

1

 [TestMethod]
    public void ToHex()
    {
        string str = "1234A";
        var result = str.Select(s =>  string.Format("0x{0:X2}", ((byte)s)));

       foreach (var item in result)
       {
           Debug.WriteLine(item);
       }

    }

edited Apr 10 '13 at 10:21

answered Apr 10 '13 at 08:36

Davut Gürbüz

5,526
4
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83

1

That outputs 0x1, 0x2, 0x3, 0x4. Not what the OP wants. – Daniel Hilgarth Apr 10 '13 at 08:38
You should delete the first, incorrect version. And you should fix the second one. It produces the correct output, but the format should look like this: `string.Format("0x{0:X2}", (int)s)`. Reasons: (1) `X8` is never used, because the value used for this parameter is a string. (2) A `char` can contain values that exceed the range of a byte. – Daniel Hilgarth Apr 10 '13 at 08:52
I just desired to show string.Format and ToString() together. I supposed chars in ASCII. byte is enough for ascii AFAIK. thanks. – Davut Gürbüz Apr 10 '13 at 09:54

score 0 · Answer 7 · answered Apr 10 '13 at 08:39

This is one I've used:

private static string ConvertToHex(byte[] bytes)
        {
            var builder = new StringBuilder();

            var hexCharacters = new[] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

            for (var i = 0; i < bytes.Length; i++)
            {
                int firstValue = (bytes[i] >> 4) & 0x0F;
                int secondValue = bytes[i] & 0x0F;

                char firstCharacter = hexCharacters[firstValue];
                char secondCharacter = hexCharacters[secondValue];

                builder.Append("0x");
                builder.Append(firstCharacter);
                builder.Append(secondCharacter);
                builder.Append(' ');
            }

            return builder.ToString().Trim(' ');
        }

And then used like:

string test = "1234";
ConvertToHex(Encoding.UTF8.GetBytes(test));

Convert from string ascii to string Hex

7 Answers7

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