Convert int32 to string in base 16

Question

I'm currently trying to convert a .NET JSON Encoder to NETMF but have hit a problem with Convert.ToString() as there isn't such thing in NETMF.

The original line of the encoder looks like this:

Convert.ToString(codepoint, 16);

And after looking at the documentation for Convert.ToString(Int32, Int32) it says it's for converting an int32 into int 2, 8, 10 or 16 by providing the int as the first parameter and the base as the second.

What are some low level code of how to do this or how would I go about doing this?

As you can see from the code, I only need conversion from an Int32 to Int16.

EDIT

Ah, the encoder also then wants to do:

PadLeft(4, '0');

on the string, is this just adding 4 '0' + '0' + '0' + '0' to the start of the string?

Answer 1

If you mean you want to change a 32-bit integer value into a string which shows the value in hexadecimal:

string hex = intValue.ToString("x");

For variations, please see Stack Overflow question Convert a number into the hex value in .NET.

Disclaimer: I'm not sure if this function exists in NETMF, but it is so fundamental that I think it should.

Answer 2

Here’s some sample code for converting an integer to hexadecimal (base 16):

int num = 48764;   // assign your number

// Generate hexadecimal number in reverse.
var sb = new StringBuilder();
do
{
    sb.Append(hexChars[num & 15]);
    num >>= 4;
} 
while (num > 0);

// Pad with leading 0s for a minimum length of 4 characters.
while (sb.Length < 4)
    sb.Append('0');

// Reverse string and get result.
char[] chars = new char[sb.Length];
sb.CopyTo(0, chars, 0, sb.Length);
Array.Reverse(chars);
string result = new string(chars);

PadLeft(4, '0') prepends leading 0s to the string to ensure a minimum length of 4 characters.

The hexChars value lookup may be trivially defined as a string:

internal static readonly string hexChars = "0123456789ABCDEF";

Edit: Replacing StringBuilder with List<char>:

// Generate hexadecimal number in reverse.
List<char> builder = new List<char>();
do
{
    builder.Add(hexChars[num & 15]);
    num >>= 4;
}
while (num > 0);

// Pad with leading 0s for a minimum length of 4 characters.
while (builder.Count < 4)
    builder.Add('0');

// Reverse string and get result.
char[] chars = new char[builder.Count];
for (int i = 0; i < builder.Count; ++i)
    chars[i] = builder[builder.Count - i - 1];
string result = new string(chars);

Note: Refer to the “Hexadecimal Number Output” section of Expert .NET Micro Framework for a discussion of this conversion.