memchr_test.p

DEF VAR mString    AS MEMPTR NO-UNDO.
DEF VAR iCheckAddr AS INT    NO-UNDO.

DEF VAR cSentence AS CHAR NO-UNDO INITIAL "The quick brown dog jumps over the lazy fox".
SET-SIZE(mString) = LENGTH(cSentence) + 1. /* Extra one is for \0 byte that gets put @ end */
PUT-STRING(mString, 1) = cSentence.

RUN memchr(GET-POINTER-VALUE(mString) + 4,
           ASC("b"),
           LENGTH(cSentence) + 1,
           OUTPUT iCheckAddr).

IF iCheckAddr = 0 THEN
  MESSAGE "Char not found in string".
ELSE DO:
  DEF VAR iIndex AS INT NO-UNDO.
  iIndex = iCheckAddr - GET-POINTER-VALUE(mString).
  MESSAGE SUBSTITUTE("Char found at (0-based) position &1",
                     iIndex).
END.

FINALLY:
  SET-SIZE(mString) = 0.
END.

PROCEDURE memchr EXTERNAL "msvcrt.dll" CDECL:
  DEFINE INPUT  PARAMETER str_ptr     AS LONG.
  DEFINE INPUT  PARAMETER char_val    AS LONG.
  DEFINE INPUT  PARAMETER check_bytes AS UNSIGNED-LONG.
  DEFINE RETURN PARAMETER ret_ptr     AS LONG.
END PROCEDURE.