Is there an IsAlpha function in QB64PE?

Is there an IsAlpha function in QB64PE? - Printable Version

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Is there an IsAlpha function in QB64PE? - PhilOfPerth - 03-31-2023

Is there an IsAlpha or IsNum (or equivalent) function in PE, to examine an input's type? If not, should there be?
I couldn't see one in Help or the Wiki.
I know we can use Select Case etc., but it would be much more convenient if these functions were available.

RE: Is there an IsAlpha function in QB64PE? - bplus - 04-01-2023

Quote:to examine an input's type

An input's type is determined by the variable that contains the value:

Code: (Select All)
Input "Enter a number"; aNum ' << single type

Print "A number"; aNum

Input "Enter a string"; aString$ ' << determines Type

Print "A string "; aString$

RE: Is there an IsAlpha function in QB64PE? - TerryRitchie - 04-01-2023

(03-31-2023, 11:56 PM)PhilOfPerth Wrote: Is there an IsAlpha or IsNum (or equivalent) function in PE, to examine an input's type? If not, should there be?
I couldn't see one in Help or the Wiki.
I know we can use Select Case etc., but it would be much more convenient if these functions were available.

Functions like those are really handy (and necessary) for languages that don't rely on, or are very flexible with, variable types. Since QB64 requires a variable to have a type (integer, single, string, etc..) there would be no reason to have an IsAlpha or IsNum function. All variables created in QB64 without specifying a type default to SINGLE, therefore they are always "IsNum" so to speak.

If you want to test a string for a numeric value use VAL().

RE: Is there an IsAlpha function in QB64PE? - PhilOfPerth - 04-01-2023

Ah, of course it is! Sorry.

RE: Is there an IsAlpha function in QB64PE? - PhilOfPerth - 04-01-2023

(04-01-2023, 12:13 AM)TerryRitchie Wrote:
(03-31-2023, 11:56 PM)PhilOfPerth Wrote: Is there an IsAlpha or IsNum (or equivalent) function in PE, to examine an input's type? If not, should there be?
I couldn't see one in Help or the Wiki.
I know we can use Select Case etc., but it would be much more convenient if these functions were available.

Functions like those are really handy (and necessary) for languages that don't rely on, or are very flexible with, variable types. Since QB64 requires a variable to have a type (integer, single, string, etc..) there would be no reason to have an IsAlpha or IsNum function. All variables created in QB64 without specifying a type default to SINGLE, therefore they are always "IsNum" so to speak.

If you want to test a string for a numeric value use VAL().

Yep, got it. Thanks Terry.

RE: Is there an IsAlpha function in QB64PE? - mnrvovrfc - 04-01-2023

https://qb64phoenix.com/qb64wiki/index.php/C_Libraries#C_Functions_and_Subs

It would be pretty easy to invent BASIC functions out of the C library ones in "ctype.h" header file.

Otherwise:

Code: (Select All)
DIM character AS INTEGER, somestring AS STRING, someposition AS LONG

character = ASC(somestring, someposition)

SELECT CASE character

CASE 44 TO 46, 48 TO 57

'(is a number)

'would have to check if plus or minus is the first character

'would have to check if there is only one of plus, minus or period

CASE 65 TO 90, 97 TO 122

'(is a letter)

CASE ELSE

'(is neither number nor letter)

END SELECT

(Declares AS INTEGER instead of AS _BYTE or AS _UNSIGNED _BYTE because those pesky negative numbers would have to be clamped away and other such calculations.)

EDIT: Added "CASE ELSE" so it could be put inside a function which should have extensive checks for number's sake, since that is more demanding than doing it to an ordinary English word apart from @#%& or other such gibberish. Smile

RE: Is there an IsAlpha function in QB64PE? - SMcNeill - 04-01-2023

https://staging.qb64phoenix.com/showthread.php?tid=1207&highlight=Isnum

RE: Is there an IsAlpha function in QB64PE? - RhoSigma - 04-01-2023

The ctype.h header is allready included in QB64pe and its functions can easily accessed via a declare library block.

Code: (Select All)
DECLARE LIBRARY

    'ctype.h

    FUNCTION isalnum% (BYVAL c AS INTEGER) 'is an alphabet letter(isalpha(c) or isdigit(c))

    FUNCTION isalpha% (BYVAL c AS INTEGER) 'is letter (isupper(c) or islower(c))

    FUNCTION isdigit% (BYVAL c AS INTEGER) 'is a decimal digit

    FUNCTION isgraph% (BYVAL c AS INTEGER) 'is a printing character other than space

    FUNCTION islower% (BYVAL c AS INTEGER) 'is a lower-case letter

    FUNCTION isprint% (BYVAL c AS INTEGER) 'is printing character. ASCII: &H20 (" ") to &H7E (~)

    FUNCTION ispunct% (BYVAL c AS INTEGER) 'is printing character other than space, letter, digit

    FUNCTION isspace% (BYVAL c AS INTEGER) 'is space, formfeed, newline, return, tab, vertical tab

    FUNCTION isupper% (BYVAL c AS INTEGER) 'is upper-case letter

    FUNCTION isxdigit% (BYVAL c AS INTEGER) 'is a hexdecimal digit character(0 thru 9 or A thru F)

END DECLARE

LINE INPUT "Gimme a char: "; c$

IF isalpha%(ASC(c$)) THEN

    PRINT "Is alpha."

ELSE

    PRINT "Is NOT alpha."

END IF

END

For more informations/other functions see https://qb64phoenix.com/qb64wiki/index.php/C_Libraries