CODEWITHSUNDEEP
haskell
Gilgamesz
Gilgamesz

Reputation: 5073

Convert string to ints. Haskell

Because of the fact I am a beginner when it comes to Haskell and generally functional programmer I would like to someone tell me how to improve my solution. The task is convert string to ints. For example:

"sada21321" -> []
"d123 32 4 123.3    32 " -> [32, 4, 32]
"FFFFFFFFFF" -> []
"      " -> []

Solution:

import Data.Char

readInts :: String -> [Int]

readInts s =  (( map convertStringToInt ) . (filter (\ elem -> (all isDigit elem))) . getSubstrings)s

getSubstrings :: String -> [String]
getSubstrings s = getSubstrings' s [] [] where
    getSubstrings' (h:t) curr res  
        | h == ' ' && (length  curr ) > 0 = getSubstrings' t [] ( res ++ [curr])
        | h /= ' ' = getSubstrings' t (curr ++ [h]) res
        | otherwise  = getSubstrings' t curr res
    getSubstrings' [] curr res = if (length curr ) > 0 then ( res ++ [curr] ) else res



reverseList :: [a] -> [a]
reverseList [] = []
reverseList (h:t) = (reverseList t) ++ [h]


convertStringToInt :: String -> Int
convertStringToInt s = convertStringToInt' (reverseList s) 1 0 
    where 
          convertStringToInt'  [] _ res    = res
          convertStringToInt' (h:t) m res = convertStringToInt' t (m*10) (res + (((ord h) - 48)*m))

Upvotes: 0

Views: 145

Answers (2)

Barış Özbaş
Barış Özbaş

Reputation: 9

Use read ("Your string here.") :: Integer and also check for read. You can convert string to mostly any types you want to.

Upvotes: 0

jamshidh
jamshidh

Reputation: 12070

You should take a look at the words and read functions.

(because this is an assignment, I'll let you fill in the details)

Upvotes: 3

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