38b08c5 · Idris-dev · git.iko.soy

git.iko.soy/Idris-dev

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String to Int function. #2639

38b08c5Saurabh Rawat11 years ago

libs/prelude/Prelude/Strings.idr+15

@@ -340,6 +340,20 @@ toUpper x with (strM x)

340 strToLower (strCons c cs) | (StrCons c cs) =

341 strCons (toUpper c) (toUpper (assert_smaller (strCons c cs) cs ))

342

343+||| Convert a number string to int.

344+|||

345+||| ```idris example

346+||| parseInt "123"

347+||| ```

348+parseInt : String -> Maybe Int

349+parseInt s with (strM s)

350+ parseInt "" | StrNil = Nothing

351+ parseInt (strCons x xs) | (StrCons x xs) = parseIntAux (unpack xs) (ord x - 48) where

352+ parseIntAux : (List Char) -> Int -> Maybe Int

353+ parseIntAux [] acc = Just acc

354+ parseIntAux (c :: cs) acc = if (c >= '0' && c <= '9') then parseIntAux cs ((acc * 10) + (ord c) - 48)

355+ else Nothing

356+

343--------------------------------------------------------------------------------

357--------------------------------------------------------------------------------

344-- Predicates

358-- Predicates

345--------------------------------------------------------------------------------

359--------------------------------------------------------------------------------

@@ -365,3 +379,4 @@ nullStr : String -> IO Bool

365nullStr p = do ok <- foreign FFI_C "isNull" (String -> IO Int) p

379nullStr p = do ok <- foreign FFI_C "isNull" (String -> IO Int) p

366 return (ok /= 0)

380 return (ok /= 0)

367

381

382+