Hexadecimal to Binary

[Trecius]

Hello, Newsgroupians:

I've a question regarding Hexadecimal to binary conversion.

Suppose I have a long hexadecimal string, and I would like to convert it to
a binary string. How can I accomplish this with minimal code? I've seen
other posts, but they are restricted to the size of the hexadecimal string,
for they use Convert.ToString(...).

EXA:

string str = "FA38";
string binStr = SomeClass.Hex2Bin(str);

This would produce the following output...

"1111101000111000"


Thank you,


Trecius

 

[Jon Skeet [C# MVP]]

I've a question regarding Hexadecimal to binary conversion.

Suppose I have a long hexadecimal string, and I would like to convert it to
a binary string. How can I accomplish this with minimal code? I've seen
other posts, but they are restricted to the size of the hexadecimal string,
for they use Convert.ToString(...).

EXA:

string str = "FA38";
string binStr = SomeClass.Hex2Bin(str);

This would produce the following output...

"1111101000111000"

Given that there are only 16 hex digits, and each hex digit maps to
exactly 4 characters, it's relatively straightforward. There are no
doubt ways to do it with shorter code than this, but this way is pretty
simple:


using System;
using System.Text;

class Test
{
static void Main()
{
string binStr = HexToBin("FA38");
Console.WriteLine(binStr);
}

static readonly string[] Nybbles =
{"0000", "0001", "0010", "0011",
"0100", "0101", "0110", "0111",
"1000", "1001", "1010", "1011",
"1100", "1101", "1110", "1111"};
static string HexToBin(string input)
{
StringBuilder builder = new StringBuilder(input.Length*4);
foreach (char c in input)
{
if (c >= '0' && c <='9')
{
builder.Append(Nybbles[c-'0']);
}
else if (c >= 'a' && c <= 'f')
{
builder.Append(Nybbles[c-'a'+10]);
}
else if (c >= 'A' && c <= 'F')
{
builder.Append(Nybbles[c-'A'+10]);
}
else
{
throw new FormatException("Invalid hex digit: "+c);
}
}
return builder.ToString();
}
}

 

[Jeroen Mostert]

I've a question regarding Hexadecimal to binary conversion.

Suppose I have a long hexadecimal string, and I would like to convert it to
a binary string. How can I accomplish this with minimal code? I've seen
other posts, but they are restricted to the size of the hexadecimal string,
for they use Convert.ToString(...).

EXA:

string str = "FA38";
string binStr = SomeClass.Hex2Bin(str);

This would produce the following output...

"1111101000111000"

There are 16 hexadecimal digits, corresponding to 16 4-bit patterns. So the
idiot's way of doing it (also called "the simplest thing that could possibly
work") would be

private static readonly string[] binarySequences = new string[] {
"0000", "0001", "0010", "0011",
"0100", "0101", "0110", "0111",
"1000", "1001", "1010", "1011",
"1100", "1101", "1110", "1111",
};

static int hexDigitToInt(char hexDigit) {
return hexDigit >= '0' && hexDigit <= '9' ? hexDigit - '0' : hexDigit
- 'A' + 10;
}
static string Hex2Bin(string hexDigits) {
StringBuilder result = new StringBuilder(hexDigits.Length * 4);
foreach (char digit in hexDigits) {
result.Append(binarySequences[hexDigitToInt(digit)]);
}
return result.ToString();
}

And despite being the idiot's way, this is actually not bad. (Once you put
in validation, that is.)

 

[Arne Vajhøj]

Suppose I have a long hexadecimal string, and I would like to convert it to
a binary string. How can I accomplish this with minimal code? I've seen
other posts, but they are restricted to the size of the hexadecimal string,
for they use Convert.ToString(...).

EXA:

string str = "FA38";
string binStr = SomeClass.Hex2Bin(str);

This would produce the following output...

"1111101000111000"

C# 2.0 / .NET 2.0:

public static string Hex2Bin20(string s)
{
StringBuilder sb = new StringBuilder();
foreach(char c in s.ToCharArray())
{

sb.Append(Convert.ToString(Convert.ToInt32(c.ToString(), 16),
2).PadLeft(4, '0'));
}
return sb.ToString();
}

C# 3.0 / .NET 3.5:

public static string Hex2Bin35(string s)
{
return String.Join("", (from c in s.ToCharArray() select
Convert.ToString(Convert.ToInt32(c.ToString(), 16), 2).PadLeft(4,
'0')).ToArray());
}

Arne

PS: I think I would use the 2.0 version on 3.5 as well - it is
more readable.

 

[parez]

Hello, Newsgroupians:

I've a question regarding Hexadecimal to binary conversion.

Suppose I have a long hexadecimal string, and I would like to convert it to
a binary string.  How can I accomplish this with minimal code?  I've seen
other posts, but they are restricted to the size of the hexadecimal string,
for they use Convert.ToString(...).

EXA:

string str = "FA38";
string binStr = SomeClass.Hex2Bin(str);

This would produce the following output...

"1111101000111000"

Thank you,

Trecius

int i = Convert.ToInt32("FA38", 16);

Console.WriteLine(Convert.ToString(i, 2));

 

[parez]

            int i = Convert.ToInt32("FA38", 16);

            Console.WriteLine(Convert.ToString(i, 2));

Sorry.. i didnt read your post all the way

 

[Arne Vajhøj]

int i = Convert.ToInt32("FA38", 16);

Console.WriteLine(Convert.ToString(i, 2));

Did you read:
"I've seen other posts, but they are restricted to the size of the
hexadecimal string, for they use Convert.ToString(...)"
?

Arne

 

[parez]

Sorry.. i didnt read your post all the way

but you could do it for each character in the string and append the
output of convert.tostring.

 

[parez]

Did you read:
   "I've seen other posts, but they are restricted to the size of the
   hexadecimal string, for they use Convert.ToString(...)"
?

Arne

hehe.. I didnt

 

[Fernando Gómez]

Hello, Newsgroupians:

I've a question regarding Hexadecimal to binary conversion.

Suppose I have a long hexadecimal string, and I would like to convert it to
a binary string. How can I accomplish this with minimal code? I've seen
other posts, but they are restricted to the size of the hexadecimal string,
for they use Convert.ToString(...).

EXA:

string str = "FA38";
string binStr = SomeClass.Hex2Bin(str);

This would produce the following output...

"1111101000111000"


Thank you,


Trecius

Hi there,

how about this? It uses int.Parse, hope that's ok.

string ToBin(string str)
{
string hex;
string bin;
int num;

bin = string.Empty;
hex = str;
num = int.Parse(hex, System.Globalization.NumberStyles.HexNumber);

while (num > 0)
{
bin = string.Format("{0}{1}", (num & 1) == 1 ? "1" : "0", bin);
num >>= 1;
}

return bin;
}

I did a little test, it seems to be working fine.

Regards.

 

[Jeroen Mostert]

C# 2.0 / .NET 2.0:

public static string Hex2Bin20(string s)
{
StringBuilder sb = new StringBuilder();
foreach(char c in s.ToCharArray())

This is unnecessary; System.String implements IEnumerable<char>.

C# 3.0 / .NET 3.5:

public static string Hex2Bin35(string s)
{
return String.Join("", (from c in s.ToCharArray() select
Convert.ToString(Convert.ToInt32(c.ToString(), 16), 2).PadLeft(4,
'0')).ToArray());
}

Without skipping on LINQ, this can easily be made more readable if desired:

public static string Hex2Bin(string hexDigits) {
return string.Concat(
(
from c in hexDigits
let hexDigit = Convert.ToInt32(c.ToString(), 16)
let binaryDigits = Convert.ToString(hexDigit, 2).PadLeft(4, '0')
select binaryDigits
).ToArray()
);
}

Or to stay in LINQ altogether:

public static string Hex2Bin(string hexDigits) {
return (
from c in hexDigits
let hexDigit = Convert.ToInt32(c.ToString(), 16)
let binaryDigits = Convert.ToString(hexDigit, 2).PadLeft(4, '0')
select binaryDigits
).Aggregate(string.Concat);
}

All that said, I would still prefer the "stupid" method of concatenating the
nybble strings yourself. While code like this makes the most out of reusing
existing code, I don't think it gains much on clarity, certainly not when
you throw in LINQ to impress your fellow programmers with.

 

[Arne Vajhøj]

This is unnecessary; System.String implements IEnumerable<char>.
Thanks.


Without skipping on LINQ, this can easily be made more readable if desired:

public static string Hex2Bin(string hexDigits) {
return string.Concat(
(
from c in hexDigits
let hexDigit = Convert.ToInt32(c.ToString(), 16)
let binaryDigits = Convert.ToString(hexDigit, 2).PadLeft(4, '0')
select binaryDigits
).ToArray()
);
}

Or to stay in LINQ altogether:

public static string Hex2Bin(string hexDigits) {
return (
from c in hexDigits
let hexDigit = Convert.ToInt32(c.ToString(), 16)
let binaryDigits = Convert.ToString(hexDigit, 2).PadLeft(4, '0')
select binaryDigits
).Aggregate(string.Concat);
}

Many ways of doing this.

But I don't really consider those more readable.

All that said, I would still prefer the "stupid" method of concatenating
the nybble strings yourself. While code like this makes the most out of
reusing existing code, I don't think it gains much on clarity, certainly
not when you throw in LINQ to impress your fellow programmers with.

That was my conclusion as well. Bytes are pretty cheap.

Arne