Convert Data to Hexadecimal in Haskell

In Haskell, we will convert Data to Hexadecimal by using intToDigit, toHex and showHex functions. In the first example, we are going to use toHex function and (stringToHex = concatMap (\c -> toHex (fromEnum c))) function and in the second example, we are going to use convertToHex x = showHex x ""). And in the third example, we are going to use (toHex = concatMap toHexChar).

Method 1: Converting Data to Hexadecimal using intToDigit and toHex function

In this method, the toHex function converts an integer to its hexadecimal representation by repeatedly dividing by 16 and converting each remainder to a digit using intToDigit. The result is reversed so that the least significant digit comes first. The stringToHex function uses fromEnum to convert each character in the input string to an integer, and then calls toHex on each integer to obtain its hexadecimal representation. The resulting hexadecimal digits are concatenated to form the final output string.

Algorithm

• Step 1 ? The Data.Char module is imported.

• Step 2 ? The toHex function is defined as,

  toHex x = reverse (toHex' x)

  where

  toHex' 0 = "0"

  toHex' n = let (q, r) = n `divMod` 16

  in if q == 0

  then [intToDigit r]

  else intToDigit r : toHex' q.

  The stringToHex function is defined as,

  stringToHex = concatMap (\c -> toHex (fromEnum c)).

• Step 3 ? The program execution will be started from main function. The main() function has whole control of the program. It is written as main = do.

• Step 4 ? The stringToHex function is called with some data.

• Step 5 ? The resultant hexadecimal value corresponding to the data is printed to the console.

Example 1

In this example, Data is converted to Hexadecimal using intToDigit and toHex function.

import Data.Char (intToDigit)

toHex :: Int -> String
toHex x = reverse (toHex' x)
   where
      toHex' 0 = "0"
      toHex' n = let (q, r) = n `divMod` 16
         in if q == 0
            then [intToDigit r]
            else intToDigit r : toHex' q

stringToHex :: String -> String
stringToHex = concatMap (\c -> toHex (fromEnum c))

main :: IO ()
main = putStrLn $ stringToHex "hello world 123"

Output

[1 of 1] Compiling Main             ( main.hs, main.o )
Linking main ...
68656c6c6f20776f726c642031323

Method 2: Converting Data to Hexadecimal using showHex function

In this method, the convertToHex function takes a value of any Integral type and converts it to a hexadecimal string using the showHex function. The second argument of showHex is a string that is appended to the end of the hexadecimal representation, which we leave empty in this case.

Algorithm

• Step 1 ? The Numeric module is imported.

• Step 2 ? The convertToHex function is defined using showHex function as,

  convertToHex x = showHex x "".

• Step 3 ? The program execution will be started from main function. The main() function has whole control of the program. It is written as main = do.

• Step 4 ? The convertToHex function is called with some value.

• Step 5 ? The resultant hexadecimal value corresponding to the data value is printed to the console.

Example 1

In this example, Data is converted to Hexadecimal using showHex function.

import Numeric (showHex)

convertToHex :: (Integral a, Show a) => a -> String
convertToHex x = showHex x ""

main :: IO ()
main = do
  let value = 255
      hex = convertToHex value
  putStrLn hex 

Output

[1 of 1] Compiling Main             ( main.hs, main.o )
Linking main ...
ff

Example 2

In this example, Data is converted to Hexadecimal using showHex function.

import Numeric

dataToHex :: (Integral a, Show a) => a -> String
dataToHex n = "0x" ++ showHex n ""

main :: IO ()
main = do
  let num = 255 :: Int
  putStrLn $ dataToHex num 

Output

[1 of 1] Compiling Main             ( main.hs, main.o )
Linking main ...
0xff

Method 3: Converting Data to Hexadecimal using concatMap and toEnum function

In this method, the toHex function takes a string as input and applies the toHexChar function to each character in the string using concatMap. The toHexChar function converts a single character to its hexadecimal representation by computing the integer value of the character, and then computing the hexadecimal digits for each nibble (4-bit) of the integer. The resulting hexadecimal digits are concatenated into a string and returned.

Algorithm

• Step 1 ? The toHex function is defined as,

  toHex = concatMap toHexChar

  where

  toHexChar c =

  let

  n = fromEnum c

  hexDigit x

  | x < 10 = toEnum (x + 48)

  | otherwise = toEnum (x + 55)

  in [hexDigit (n `div` 16), hexDigit (n `mod` 16)].

• Step 2 ? The program execution will be started from main function. The main() function has whole control of the program. It is written as main = do.

• Step 3 ? The toHex function is called with some value.

• Step 4 ? The resultant hexadecimal value corresponding to the data value is printed to the console.

Example 1

In this example, Data is converted to Hexadecimal using concatMap and toEnum function.

toHex :: String -> String
toHex = concatMap toHexChar
  where
    toHexChar c =
      let
        n = fromEnum c
        hexDigit x
          | x < 10    = toEnum (x + 48)
          | otherwise = toEnum (x + 55)
      in [hexDigit (n `div` 16), hexDigit (n `mod` 16)]
main :: IO ()
main = putStrLn $ toHex "hello world 123" 

Output

[1 of 1] Compiling Main             ( main.hs, main.o )
Linking main ...
68656C6C6F20776F726C6420313233

Conclusion

In Haskell, data to hexadecimal conversion refers to the process of converting a given data or value into a hexadecimal string. Hexadecimal representation is a commonly used format to represent binary data or memory addresses, as it is easy to read and write. There are various ways to perform this conversion in Haskell, depending on the desired implementation and requirements.