Is number

[Mike Doty]

Here is a solution.
If a tests fails, add an OR statement and please let us know. No scientific notation.

FUNCTION isNumeric(Answer AS STRING) AS LONG
  Answer = TRIM$(Answer) 'may be required if right-justified text
  IF (LEN(Answer) = 0)                  OR _
     (VERIFY (Answer , ".-0123456789")) OR _
     (RIGHT$(Answer,1) = ".")           OR _
     (INSTR(-1,Answer,"-") > 1)         OR _
     (TALLY(Answer,".") > 1) THEN
     EXIT FUNCTION  'exit, return 0 not-numeric
  END IF
  FUNCTION = -1 'numeric
END FUNCTION

[Pierre Bellisle]

If right-justified text is accepted,
then because it is often shown with the minus sign at the beginning, like this:

- 123
-  12
-   1

I would add

Answer = LEFT$(Answer, INSTR(Answer, "-")) & _
LTRIM$(MID$(Answer, INSTR(Answer, "-") + 1))

before the IF line.

Pierre

[Mike Doty]

The TRIM$ isn't enough?
I see, allow spaces after minus sign.
Might add BYVAL Answer AS STRING since input string is being modified.
Thank you, will incorporate.


Good improvements by Pierre, below in post # 24.

[Pierre Bellisle]

Hey Mike,
Once started, we could also accept a plus sign prefix...

 
FUNCTION isNumeric2(BYVAL Answer AS STRING) AS LONG
  Answer = TRIM$(Answer) 'Trim spaces, may be required in right-justified text for example
  Answer = LEFT$(Answer, INSTR(Answer, ANY "+-")) & _        'In case of space after the sign,
           LTRIM$(MID$(Answer, INSTR(Answer, ANY "+-") + 1)) ' "- 123" for example
  'PRINT Answer & "<"
  IF (LEN(Answer) = 0)                   OR _  'Exclude null string
     (VERIFY (Answer , ".-+0123456789")) OR _  'Accept only valid characters
     (INSTR(-1, Answer, "+") > 1)        OR _  'Plus must be on digit's left
     (INSTR(-1, Answer, "-") > 1)        OR _  'Minus must be on digit's left
     (RIGHT$(Answer, 1) = ".")           OR _  'Must not end with a dot
     (TALLY(Answer, ".") > 1)            THEN  'No more than one dot
     EXIT FUNCTION  'Return zero, not a number
  END IF
  FUNCTION = -1 'Its a number
END FUNCTION

[Pierre Bellisle]

>...improvements by Pierre...

'twas easy, I only added a little block on a well made foundation. :-)

Pierre

[Mike Doty]

Verify also needed to check for +

#DIM ALL
FUNCTION PBMAIN () AS LONG
  LOCAL sTitle,MY_STRING AS STRING
  MY_STRING = "1234567"
  DO
    MY_STRING = INPUTBOX$("Type anything",sTitle,MY_STRING)
    IF LEN(MY_STRING) = 0 THEN EXIT DO
    IF IsNumeric(MY_STRING) THEN
      sTitle = "ITS A NUMBER!"
    ELSE
      sTitle = "NOT A NUMBER"
      BEEP
    END IF
  LOOP
END FUNCTION

FUNCTION isNumeric(Answer AS STRING) AS LONG
  Answer = TRIM$(Answer)
  IF (LEN(Answer) = 0)                OR _
   (VERIFY (Answer , ".-+0123456789"))OR _
   (RIGHT$(Answer,1) = ".")           OR _
   (INSTR(-1,Answer,"-") > 1)         OR _
   (ASC(Answer)=45 AND LEN(Answer)=1) OR _
   (TALLY(Answer,".") > 1) THEN
   EXIT FUNCTION  'exit, return 0 not-numeric
  END IF
  FUNCTION = 1
END FUNCTION

[George Bleck]

Just to stir the pot a little but also just so it is said... remember that MANY regions use the comma, period, and space differently to represent the radix and thousands separator characters.

Whatever function you use needs to be regionally specific OR it would require you code some really complex rulesets to allow all.

These all could be considered valid numbers...

• 1234.56
• 1234,56
• 1,234.56
• 1.234,56
• 1 234.56
• 1 234,56

Seeing a number like 12,345 could be VERY confusing depending on context.

Is it 12 thousand, three hundred forty-five?
or is it 12 and 345 thousandths?

[Mike Doty]

Found some more to exclude as valid
Others suggested BYVAL which was missing
Scientific notation is not considered
https://forum.powerbasic.com/forum/u...umeric?t=43051
Scientific notation is not considered

1+1 returns valid so needs more work

#DIM ALL
FUNCTION PBMAIN () AS LONG                   'ISNUMBER.BAS  so can find in the future
  LOCAL sTitle,MY_STRING AS STRING
  MY_STRING = "1234567"
  DO
    MY_STRING = INPUTBOX$("Type anything",sTitle,MY_STRING)
    IF LEN(MY_STRING) = 0 THEN EXIT DO
    IF IsNumeric(MY_STRING) THEN
      sTitle = "ITS A NUMBER!"
    ELSE
      sTitle = "NOT A NUMBER"
      BEEP
    END IF
  LOOP
END FUNCTION

FUNCTION isNumeric(BYVAL Answer AS STRING) AS LONG
  Answer = TRIM$(Answer)
  IF (LEN(Answer) = 0)                OR _
   (VERIFY (Answer , ".-+0123456789"))OR _
   (RIGHT$(Answer,1) = ".")           OR _
   (RIGHT$(Answer,1) = "+")           OR _
   (RIGHT$(Answer,1) = "-")           OR _
   (INSTR(-1,Answer,"-") > 1)         OR _
   (TALLY(Answer,".") > 1) THEN
   EXIT FUNCTION  'exit, return 0 not-numeric
  END IF
  FUNCTION = 1
END FUNCTION

handle 1+1

FUNCTION isNumeric(BYVAL Answer AS STRING) AS LONG
  Answer = TRIM$(Answer)
  IF (LEN(Answer) = 0)                OR _
   (VERIFY (Answer , ".-+0123456789"))OR _
   (RIGHT$(Answer,1) = ".")           OR _
   (RIGHT$(Answer,1) = "+")           OR _
   (RIGHT$(Answer,1) = "-")           OR _
   (INSTR(-1,Answer,"-") > 1)         OR _
   (INSTR(-1,Answer,"+") > 1)         OR _
   (TALLY(Answer,".") > 1) THEN
   EXIT FUNCTION  'exit, return 0 not-numeric
  END IF
  FUNCTION = 1
END FUNCTION

Got rid of tally, more consistent, but maybe tally was better

#DIM ALL
FUNCTION PBMAIN () AS LONG
  LOCAL sTitle,MY_STRING AS STRING
  MY_STRING = "1234567"
  DO
    MY_STRING = INPUTBOX$("Type anything",sTitle,MY_STRING)
    IF LEN(MY_STRING) = 0 THEN EXIT DO
    IF IsNumeric(MY_STRING) THEN
      sTitle = "ITS A NUMBER!"
    ELSE
      sTitle = "NOT A NUMBER"
      BEEP
    END IF
  LOOP
END FUNCTION

FUNCTION isNumeric(BYVAL Answer AS STRING) AS LONG
  Answer = TRIM$(Answer)
  IF (LEN(Answer) = 0)                OR _
   (VERIFY (Answer , ".-+0123456789"))OR _
   (RIGHT$(Answer,1) = ".")           OR _
   (RIGHT$(Answer,1) = "+")           OR _
   (RIGHT$(Answer,1) = "-")           OR _
   (INSTR(-1,Answer,".") > 1)         OR _
   (INSTR(-1,Answer,"+") > 1)         OR _
   (INSTR(-1,Answer,"-") >1)   THEN
   EXIT FUNCTION  'exit, return 0 not-numeric
  END IF
  FUNCTION = 1
END FUNCTION

[Chris Chancellor]

Hello Mike
Pretty good but it cannot handle comma

[Mike Doty]

I hear ya.
One way of looking at comma is that it is not a valid digit, but only for formatting.

Using INSTR instead of TALLY broke routine using 1.1 so Tally is back.

#DIM ALL
FUNCTION PBMAIN () AS LONG
  LOCAL sTitle,MY_STRING AS STRING
  MY_STRING = "1234567"
  DO
    MY_STRING = INPUTBOX$("Type anything",sTitle,MY_STRING)
    IF LEN(MY_STRING) = 0 THEN EXIT DO
    IF IsNumeric(MY_STRING) THEN
      sTitle = "ITS A NUMBER!"
    ELSE
      sTitle = "NOT A NUMBER"
      BEEP
    END IF
  LOOP
END FUNCTION

FUNCTION isNumeric(BYVAL Answer AS STRING) AS LONG
  Answer = TRIM$(Answer)
  IF (LEN(Answer) = 0)                OR _
   (VERIFY (Answer , ".-+0123456789"))OR _
   (RIGHT$(Answer,1) = ".")           OR _
   (RIGHT$(Answer,1) = "+")           OR _
   (RIGHT$(Answer,1) = "-")           OR _
   (INSTR(-1,Answer,"-") > 1)         OR _
   (INSTR(-1,Answer,"+") > 1)         OR _
   (TALLY(Answer,".") > 1) THEN
   EXIT FUNCTION  'exit, return 0 not-numeric
  END IF
  FUNCTION = 1
END FUNCTION

[Chris Chancellor]

Mike, maybe allow commas to be entered first into function isNumeric
Initially check Answer for commas and then remove them and then check test results for numeric

Maybe need a 2 stage process inside function isNumeric
first stage --> remove commas to become Answer
second stage --> test Answer for numeric

[George Bleck]

regarding commas/decimals make sure you read my post #27 as it is already being lost in the static.

[Chris Chancellor]

maybe like this ?

#COMPILE EXE
#DIM ALL

' Check Numeric.bas
' https://forum.powerbasic.com/forum/user-to-user-discussions/programming/61574-is-number/page2


FUNCTION PBMAIN () AS LONG
  LOCAL sTitle,MY_STRING, RtString AS STRING
  MY_STRING = "1234567"
  DO
    MY_STRING = INPUTBOX$("Type anything",sTitle,MY_STRING)
    IF LEN(MY_STRING  ) = 0 THEN EXIT DO
    IF IsNumeric(MY_STRING, RtString) THEN
      ?  "ITS A NUMBER!" + $CRLF + _
       STR$(VAL(RtSTRING))
    ELSE
        BEEP
      ? "NOT A NUMBER"

    END IF
  LOOP

END FUNCTION

 FUNCTION oldisNumeric(Answer AS STRING) AS LONG
  Answer = TRIM$(Answer)
  IF (LEN(Answer) = 0)                OR _
   (VERIFY (Answer , ".-+0123456789"))OR _
   (RIGHT$(Answer,1) = ".")           OR _
   (INSTR(-1,Answer,"-") > 1)         OR _
   (ASC(Answer)=45 AND LEN(Answer)=1) OR _
   (TALLY(Answer,".") > 1) THEN
   EXIT FUNCTION  'exit, return 0 not-numeric
  END IF
  FUNCTION = 1
END FUNCTION



  FUNCTION isNumeric(BYVAL Answer AS STRING, newAnswer AS STRING) AS LONG

  Answer = TRIM$(Answer)
  newAnswer = ""
  'remove all commas if any
  REPLACE "," WITH "" IN answer
  REPLACE " " WITH "" IN answer

  IF (LEN(Answer) = 0)                OR _
   (VERIFY (Answer , ".-+0123456789"))OR _
   (RIGHT$(Answer,1) = ".")           OR _
   (RIGHT$(Answer,1) = "+")           OR _
   (RIGHT$(Answer,1) = "-")           OR _
   (INSTR(-1,Answer,"-") > 1)         OR _
   (INSTR(-1,Answer,"+") > 1)         OR _
   (TALLY(Answer,".") > 1) THEN
   EXIT FUNCTION  'exit, return 0 not-numeric
  END IF
  newAnswer = Answer
  FUNCTION = 1
END FUNCTION

[Michael Mattias]

Pretty good but it cannot handle comma

Comma is not numeric. As Mike Doty says ".. way of looking at comma is that it is not a valid digit, but only for formatting."

But now (not that it's a 'first' here) a question other than that which was asked is being addressed: it's no longer " does string 'x' represent a number?" but rather it becomes " does string 'x' represent a number or a formatted number?"

And let me screw up this comma thing (and decimal point thing) forever: in Europe the usage of the comma and the decimal point is reversed from the usage here in the States for formatting numbers.

Comma usage can be important! Like I saw on a t-shirt worn by one of my classmates at my Silver Sneakers(r) fitness classes:

{picture of a nice meal}

Let's eat Grandma.
Let's eat, Grandma.
Commas Save Lives!


MCM

[Eric Pearson]

> Comma is not numeric.

https://en.wikipedia.org/wiki/Decima..._decimal_comma

[Borje Hagsten]

Since value isn't really important, Remove$ can be used to remove spaces, commas and dots, etc before numeric test.
Combination IsCharAlphaNumeric <> 0 and IsCharAlpha = 0 returns following as numeric: 0123456789²³¹
Try testing 2² (^ should also be sort of numeric, or..?)

[Michael Mattias]

Since value isn't really important, Remove$ can be used to remove spaces, commas and dots, etc before numeric test.

There's really no difference I can see between

    ToTest$ =  REMOVE$(RawString$, some_set_characters_defined_non_numeric)
     CALL testochoice (ToTest$) TO iResult

AND

    ToTest$ =  RETAIN$(RawString$, some_set_characters_defined_are_numeric)
     CALL testochoice (ToTest$) TO iResult

It's not really in the test, it's in the defining of the allowed characters, their frequency/permitted occurrences, their positions within 'RawString$' and any required or prohibited relationships between and/or among characters.

The question "Does this string represent a number?" is simply too Insufficient and too incomplete to expect THE ONE TRUE ANSWER.

[Jim Robinson]

I found the IsNumeric routine here some years ago. I'm pretty sure it was something Hutch shared, but it could be someone else... so many contributors here.

I modified the basic routine to fit some particular needs.

'--------------------------------------------------------------------------------
'- String Validataion routines:
'-  IsAlpha     - returns true if all letters                (A-Z,a-z)
'-  IsAlphaEX   - returns true if all letters and/or blanks  (A-Z,a-z," ")
'-  IsCapAlpha  - returns true if all capital letters        (A-Z)
'-  IsNumeric   - returns true if all numbers                (0-9)
'-  IsNumericEX - returns true if all numbers, commas, decimal points, plus, minus eg: -1,234.56 = True
'-  IsZIP       - returns true if all numbers and/or dash    (0-9, "-")
'-  IsDollars   - returns true is all numbers, commas, decimal points, dollar signs (0-9,",",".","$")
'-  IsAlphaNumeric - returns true if all numbers and/or letters (A-Z,a-z,0-9)

'--------------------------------------------------------------------------------
'===============================================================================================
'// Returns 1 if a string is an alpha char (A-Z,a-z)
FUNCTION IsCapAlpha(s AS STRING) AS LONG
#REGISTER NONE
LOCAL sPtr&, sLen&
   ON ERROR RESUME NEXT
   sPtr = STRPTR(s)
   sLen& = STRPTR(s) + LEN(s)
   ! mov eax, sPtr ;ptr to string
   ! mov ecx, sLen ;addr: end of string
StartLoop529:
   ! mov bl, [eax]
   ! cmp bl, 65
   ! jl  NotAlpha529  ; < 65? Not alpha
   ! cmp bl, 90
   ! jg  NotAlpha529  ; > 90? Not alpha
Alpha529:
   ! inc eax
   ! cmp eax, ecx
   ! je  EndLoop529
   ! jmp StartLoop529
NotAlpha529:
   FUNCTION = False
   EXIT FUNCTION
EndLoop529:
   FUNCTION = True
END FUNCTION

FUNCTION IsAlpha(s AS STRING) AS LONG
#REGISTER NONE
LOCAL sPtr&, sLen&
   ON ERROR RESUME NEXT
   sPtr = STRPTR(s)
   sLen& = STRPTR(s) + LEN(s)
   ! mov eax, sPtr ;ptr to string
   ! mov ecx, sLen ;addr: end of string
StartLoop530:
   ! mov bl, [eax]
   ! cmp bl, 65
   ! jl  NotAlpha530  ; < 65? Not alpha
   ! cmp bl, 122
   ! jg  NotAlpha530  ; > 122? Not alpha
   ! cmp bl, 91
   ! jl  Alpha530     ; < 91? Alpha
   ! cmp bl, 97
   ! jl NotAlpha530   ; < 97? Not alpha
Alpha530:
   ! inc eax
   ! cmp eax, ecx
   ! je  EndLoop530
   ! jmp StartLoop530
NotAlpha530:
   FUNCTION = False
   EXIT FUNCTION
EndLoop530:
   FUNCTION = True
END FUNCTION

FUNCTION IsAlphaEX(s AS STRING) AS LONG
#REGISTER NONE
LOCAL sPtr&, sLen&
   ON ERROR RESUME NEXT
   sPtr = STRPTR(s)
   sLen& = STRPTR(s) + LEN(s)
   ! mov eax, sPtr ;ptr to string
   ! mov ecx, sLen ;addr: end of string
StartLoop530x:
   ! mov bl, [eax]
   ! cmp bl, 32       ; a blank is ok too
   ! je  Alpha530x
   ! cmp bl, 65
   ! jl  NotAlpha530x  ; < 65? Not alpha
   ! cmp bl, 122
   ! jg  NotAlpha530x  ; > 122? Not alpha
   ! cmp bl, 91
   ! jl  Alpha530x     ; < 91? Alpha
   ! cmp bl, 97
   ! jl NotAlpha530x   ; < 97? Not alpha
Alpha530x:
   ! inc eax
   ! cmp eax, ecx
   ! je  EndLoop530x
   ! jmp StartLoop530x
NotAlpha530x:
   FUNCTION = False
   EXIT FUNCTION
EndLoop530x:
   FUNCTION = True
END FUNCTION

'===============================================================================================
'// Returns 1 if a string is numeric (0-9)
FUNCTION IsNumeric(s AS STRING) AS LONG
#REGISTER NONE
LOCAL sPtr&, sLen&

   ON ERROR RESUME NEXT
   sPtr = STRPTR(s)
   sLen& = STRPTR(s) + LEN(s)
   ! mov eax, sPtr ;ptr to string
   ! mov ecx, sLen ;addr: end of string
StartLoop531:
   ! mov bl, [eax]
   ! cmp bl, 48
   ! jl  NotNumeric531  ; < 48? Not numeric
   ! cmp bl, 57
   ! jg  NotNumeric531  ; > 57? Not numeric
   ! inc eax
   ! cmp eax, ecx
   ! je  EndLoop531
   ! jmp StartLoop531
NotNumeric531:
   FUNCTION = False
   EXIT FUNCTION
EndLoop531:
   FUNCTION = True
END FUNCTION

'// Returns 1 if a string is numeric (0 through 9, and the Plus (+), Minus(-), and  Decimal (.)
FUNCTION IsNumericEX(s AS STRING) AS LONG
#REGISTER NONE
LOCAL sPtr&, sLen&
   ON ERROR RESUME NEXT
   sPtr = STRPTR(s)
   sLen& = STRPTR(s) + LEN(s)
   ! mov eax, sPtr ;ptr to string
   ! mov ecx, sLen ;addr: end of string
StartLoop533:
   ! mov bl, [eax]
   ! cmp bl, 43
   ! jl  NotNumeric533   ; lower than minus
   ! cmp bl, 46
   ! jle OKgoon533   ;  is decimal, or comma, or plus, or minus
   ! cmp bl, 48
   ! jl  NotNumeric533  ; < 48? Not numeric
   ! cmp bl, 57
   ! jg  NotNumeric533  ; > 57? Not numeric
OKgoon533:
   ! inc eax
   ! cmp eax, ecx
   ! je  EndLoop533
   ! jmp StartLoop533
NotNumeric533:
   FUNCTION = False
   EXIT FUNCTION
EndLoop533:
   FUNCTION = True
END FUNCTION

' like IsNumeric, except allows a DASH
FUNCTION IsZIP(s AS STRING) AS LONG
#REGISTER NONE
LOCAL sPtr&, sLen&
   ON ERROR RESUME NEXT
   sPtr = STRPTR(s)
   sLen& = STRPTR(s) + LEN(s)
   ! mov eax, sPtr ;ptr to string
   ! mov ecx, sLen ;addr: end of string
StartLoop534:
   ! mov bl, [eax]
   ! cmp bl, 45
   ! je  OKgoon534      ;  is a dash
   ! cmp bl, 48
   ! jl  NotNumeric534  ; < 48? Not numeric
   ! cmp bl, 57
   ! jg  NotNumeric534  ; > 57? Not numeric
OKgoon534:
   ! inc eax
   ! cmp eax, ecx
   ! je  EndLoop534
   ! jmp StartLoop534
NotNumeric534:
   FUNCTION = False
   EXIT FUNCTION
EndLoop534:
   FUNCTION = True
END FUNCTION

' like IsNumeric, except allows a commas, decimals, dollar signs
FUNCTION IsDollars(s AS STRING) AS LONG
#REGISTER NONE
LOCAL sPtr&, sLen&
   ON ERROR RESUME NEXT
   sPtr = STRPTR(s)
   sLen& = STRPTR(s) + LEN(s)
   ! mov eax, sPtr ;ptr to string
   ! mov ecx, sLen ;addr: end of string
StartLoop535:
   ! mov bl, [eax]
   ! cmp bl, 36
   ! je  OKgoon535      ;  is a $
   ! cmp bl, 44
   ! je  OKgoon535      ;  is a ,
   ! cmp bl, 46
   ! je  OKgoon535      ;  is a .
   ! cmp bl, 48
   ! jl  NotNumeric535  ; < 48? Not numeric
   ! cmp bl, 57
   ! jg  NotNumeric535  ; > 57? Not numeric
OKgoon535:
   ! inc eax
   ! cmp eax, ecx
   ! je  EndLoop535
   ! jmp StartLoop535
NotNumeric535:
   FUNCTION = False
   EXIT FUNCTION
EndLoop535:
   FUNCTION = True
END FUNCTION


'===============================================================================================
'// Returns 1 if a string is alphanumeric (A-Z,a-z,0-9)
FUNCTION IsAlphanumeric(s AS STRING) AS LONG
#REGISTER NONE
LOCAL sPtr&, sLen&
   ON ERROR RESUME NEXT
   sPtr = STRPTR(s) - 1
   sLen& = STRPTR(s) + LEN(s)
   ! mov eax, sPtr ;ptr to string
   ! mov ecx, sLen ;addr: end of string
StartLoop532:
   ! inc eax
   ! cmp eax, ecx
   ! je  EndLoop532
   ! mov bl, [eax]
   ! cmp bl, 65
   ! jl  NotAlpha532   ; < 65? Not alpha
   ! cmp bl, 122
   ! jg  NotNumeric532 ; > 122? Not NotNumeric
   ! cmp bl, 91
   ! jl  Alpha532      ; < 91? Alpha
   ! cmp bl, 97
   ! jl NotAlpha532    ; < 97? Not alpha
Alpha532:
   ! jmp StartLoop532
NotAlpha532:
   ! cmp bl, 48
   ! jl NotNumeric532  ; < 48? Not numeric
   ! cmp bl, 57
   ! jg NotNumeric532  ; > 57? Not numeric
   ! jmp StartLoop532
NotNumeric532:
   FUNCTION = False
   EXIT FUNCTION
EndLoop532:
   FUNCTION = True
END FUNCTION

'--------------------------------------------------------------------------------

[Rodney Hicks]

It seems to me that VAL solves this problem:
Syntax:

VAL StrgExpr [, offset] TO ValueVar [, DigitsVar&, UnusedVar&]

If the Unusedvar$ has content, then StrExpr is not a number even if it has content that have a numeric flavor. The OP wanted to know if it was a number.

[Eric Pearson]

Clever idea, using the UnusedVar& value, but...

I'm usually not a fan of VAL because it interprets a ton of non-numeric characters as numeric. For example VAL("9D9") produces "9000000000". These characters...

01234567890.-+&AaBbCcDdEeFfHhOoQq + CHR$(9,32)

...can all be interpreted as "not non-numeric" by VAL. Also, VAL says "9" is not a numeric character if the string starts with &o... lots and lots of pitfalls.