Numeric Test

[hal9k]

Is there a good way to do a numeric test?  I couldn't find one, so I wrote this "brute force" function, but I suspect there is a better way.

Thanks!

FUNCTION FN.IsNumeric(String$) 'This function returns 1 if the string is numeric

FN.IsNumeric = 1 'let's assume it's numeric
FOR i = 1 TO LEN(String$)
    test = ASC(MID$(String$, i, 1))
    IF test < 48 OR test > 57 THEN
        FN.IsNumeric = 0
        EXIT FOR
    END IF
NEXT i
END FUNCTION

[Walt Decker]

How about:

FUNCTION FN.IsNumeric(StrIn$)

True = 1
NumStr$ = ""

NumStr$ = STR$(VAL(StrIn$))

IF LEN(NumStr$) < LEN(StrIn$) THEN
 EXIT FUNCTION
END IF
FN.IsNumeric = True
END FUNCTION

Your function does not consider the possibility of a decimal number.

Also, you could compare each byte to the magic string "-+0123456789." and save a bit of conversion.

[tsh73]

It really depend on how numeric it will be.
If you want to check if string makes valid number
(including floating point and scientific notation),
have a look at this program from old 2008 contest.

(here, function isNumber uses auxiliary function eatUp below it)

'v. 02 - now start my own func
data "valid"
data "0", "0.", "0.0", "1.0"
data "1", "-1", "123","-123"
data "1.", ".1", "1.1"
data "-1.", "-.1", "-1.1"
data "1e2", ".1e2", "1.1e2"
data "1e-2", ".1e-2", "1.1e-2"
data "-1e-2", "-.1e-2", "-1.1e-2"
data "0.0000000001", "7987987987987987", "7987987987987987.3", "1.03e-41"
data "not valid"
data "."    'actually JB consider it 0.0  -??
data "1 2", "- 1", "--1"
data "1e", "1d2", "1-2", "1e2.5"
data "1.2^2", "1.2+3"
'data  "1ee2"    'specially for my function
'data "1e1000"  'float overlow if you try to VAL() it
data "over"

global True, False
False = 0
True = 1
dim failed(True), passed(True)

read input$
while 1
   input$ = trim$(input$)  'just for the case
   select case input$
   case "valid"
       goal = True
       print "Checking VALID"
   case "not valid"
       'first report progress so far
       print "Passed: ";passed(goal);" Failed: ";failed(goal)
       goal = False
       print "Checking NOT VALID"
   case "over"
       exit while
   case else
       'print input$, goal
       print input$,
       'res = check1(input$)
       'res = check2(input$)
       'res = check3(input$)
       res = IsNumber(input$)
       'print res,
       if res = goal then
           passed(goal)= passed(goal)+1
           print "Passed"
       else
           failed(goal)= failed(goal)+1
           print "Failed"
       end if
   end select
   read input$
wend
print "Passed: ";passed(goal);" Failed: ";failed(goal)
'then report totals
print "Total:"
print "Passed: ";passed(0)+passed(1);" Failed: ";failed(0)+failed(1)
print "-- Over! --"

end

'===========================================
'-------------------------------------------
'simple check by Henry
function check1(var$)
   res=True
   if var$<>str$(val(var$)) then res=False
   check1 = res
end function

'-------------------------------------------
'first try by timbim (adapted to return True or False)
function check2(var$)
   res=True
   if checknum$(var$) = "Error" then res=False
   check2 = res
end function

function checknum$(var$)
var$ = trim$(var$)
leng = len(var$)
tot = 0
for x = 1 to leng
    if asc(mid$(var$, x, 1)) = 46 then point = point + 1
    if asc(mid$(var$, x, 1)) > 57 or asc(mid$(var$, x, 1)) < 48 and asc(mid$(var$, x, 1)) <> 46 then err = 1
next
if err = 1 or point > 1 then checknum$ = "Error" else checknum$ = "No error"
end function
'-------------------------------------
'suggestion by Rod
function check3(var$)
   res = False
   num=val(var$)
   if num<> 0 and num-num=0 then res = True
   check3 = res
end function
'-------------------------------------
'tsh73 try
'credits for the idea goes to Jack W. Crenshaw
'in his tutorials "LET'S BUILD A COMPILER!"
'he used something like that for parsing expressions
function IsNumber(input$)
'checks input$ for being valid number. Returns True if yes, False otherwise.
   IsNumber = 0
   'check sign
   ns = eatUp(input$, "+-")
   if ns>1 then exit function 'with False
   'now, digits
   n1 = eatUp(input$, "0123456789")
   'could be decimal point
   nd = eatUp(input$, ".")
   if nd>1 then  exit function
   'then again, digits
   n2 = eatUp(input$, "0123456789")
   if n1+n2<1 then  exit function
   'now, exponent
   ne = eatUp(input$, "e")
   if ne<>0 then   'we have exponent
       if ne>1 then  exit function
       'check sign
       ns = eatUp(input$, "+-")
       if ns>1 then  exit function
       'now, digits
       n1 = eatUp(input$, "0123456789")
       if n1<1 then  exit function
   end if

   if input$="" then IsNumber = 1: exit function
   'else we have leftovers - over with False
end function

function eatUp(byRef input$, chars2eat$)
'trims all leading chars from  input$ that match chars in chars2eat$
'return count of trimmed characters
   count = 0
   while len(input$)>0
       if instr( chars2eat$, left$( input$,1))<>0 then
           input$ = mid$(input$,2)
           count = count +1
       else
           exit while
       end if
   wend
   eatUp = count
end function



[hal9k]

Thanks guys. I was hoping somebody would tell me about the undocumented NUMERIC function in LB, but no such luck.

I'll incorporate your ideas and remember them for the future.

[Rod]

If this is about user input you can of course control the actual input. You can with stylebits limit the input to numeric characters. You can with a combobox or series of comboboxes take complete control of the input.

alycesrestaurant.com/lbpe/Stylebits%20-%20Textboxes.html shows how to limit input to numeric characters.

This is kinda clunky but the user can't input anything other than the numbers I offer.

   WindowWidth = 800
   WindowHeight = 400
   'nomainwin
   a$(1) = "1"
   a$(2) = "2"
   a$(3) = "3"
   a$(4) = "4"
   a$(5) = "5"
   a$(6) = "6"
   a$(7) = "7"
   a$(8) = "8"
   a$(9) = "9"
   a$(0) = "0"

   listbox #win.l1, a$(),dolist,10,10,45,140
   listbox #win.l2, a$(),dolist,65,10,45,140
   listbox #win.l3, a$(),dolist,120,10,45,140
   button #win.b1,"Enter",[check],UL,185,10,50,20
   open "Listbox Numeric Demo" for window as #win
   #win "trapclose [quit]"
   #win.l1 "selectindex 1"
   #win.l2 "selectindex 1"
   #win.l3 "selectindex 1"
   wait

   [check]
   #win.l1 "selection? v1$"
   #win.l2 "selection? v2$"
   #win.l3 "selection? v3$"
   v=100*val(v1$)+10*val(v2$)+val(v3$)
   print v
   wait


   [quit]
   close #win
   end

   sub dolist h$
   end sub



[Walt Decker]

Mr. Pryor you might consider:

'
Str0$ = "&hFF"
A$ = FN.IsNumber$(Str0$, Yes)
PRINT A$, Yes

Str1$ = "-123"
A$ = FN.IsNumber$(Str1$, Yes)
PRINT A$, Yes

Str2$ = "-123 abc"
A$ = FN.IsNumber$(Str2$, Yes)
PRINT A$, Yes
Str3$ = "123abc"
A$ = FN.IsNumber$(Str3$, Yes)
PRINT A$, Yes

Str4$ = "123 abc"
A$ = FN.IsNumber$(Str4$, Yes)
PRINT A$, Yes

Str5$ = "-abc123"
A$ = FN.IsNumber$(Str5$, Yes)
PRINT A$, Yes

Str6$ = "-abc 123"
A$ = FN.IsNumber$(Str6$, Yes)
PRINT A$, Yes

Str7$ = "-4.123abc"
A$ = FN.IsNumber$(Str7$, Yes)
PRINT A$, Yes

Str8$ = "4.123abc"
A$ = FN.IsNumber$(Str8$, Yes)
PRINT A$, Yes

Str9$ = "-4.123 abc"
A$ = FN.IsNumber$(Str9$, Yes)
PRINT A$, Yes
TRACE 2
Str10$ = "aebc-4.123"
A$ = FN.IsNumber$(Str10$, Yes)
PRINT A$, Yes

Str11$ = "253690.1578"
A$ = FN.IsNumber$(Str11$, Yes)
PRINT A$, Yes

Str11$ = "-4.1234698e12"
A$ = FN.IsNumber$(Str11$, Yes)
PRINT A$, Yes
END
FUNCTION FN.IsNumber$(NumStr$, BYREF True)

StrIn$ = ""
Magic$ = "+-.0123456789E"

True   = 1
LenIn  = 0
LenNum = 0

StrIn$ = UPPER$(NumStr$)
FOR I = 1 TO LEN(StrIn$)
 IF INSTR(Magic$, MID$(StrIn$, I, 1)) = 0 THEN
   True = 0
   FN.IsNumber$ = NumStr$
   EXIT FUNCTION
 END IF
NEXT I

FN.IsNumber$ = NumStr$
END FUNCTION

'

You might want to put code in the function to handle hex numbers.

[rnbw]

Oct 11, 2022 13:38:11 GMT -5 hal9k said:

Is there a good way to do a numeric test?  I couldn't find one, so I wrote this "brute force" function, but I suspect there is a better way.

Thanks!

FUNCTION FN.IsNumeric(String$) 'This function returns 1 if the string is numeric

FN.IsNumeric = 1 'let's assume it's numeric
FOR i = 1 TO LEN(String$)
    test = ASC(MID$(String$, i, 1))
    IF test < 48 OR test > 57 THEN
        FN.IsNumeric = 0
        EXIT FOR
    END IF
NEXT i
END FUNCTION

Does this help.  It is from Liberty Newsletter #121 June 2004

' FUNCTION NumberOnly$()  -  Bob Bromley  -  May 5, 2004

   ' Function is passed a string, discards any character that is not a number, a decimal point,
   ' or a minus sign (as long as it preceeds the number) and returns the result.

   ' NOTE: Numbers > 99,999,999.94 will return in exponential form.
   '       Numbers > 10,000,000 will round out to the nearest 10?.

nomainwin

WindowWidth = 300 : WindowHeight = 230
UpperLeftX = int((DisplayWidth  - WindowWidth)  / 2)
UpperLeftY = int((DisplayHeight - WindowHeight) / 2)
statictext #main.stat.1, "Enter something,  (mix characters and numbers)", 35,  15, 290, 20
Stylebits #main.text.1, _ES_RIGHT, _WS_BORDER, 0, 0
textbox    #main.text.1, 35,  40, 220, 25
statictext #main.stat.2, "The numeric result is", 90,  90, 100, 20
Stylebits #main.text.2, _ES_RIGHT, _WS_BORDER, 0, 0
textbox    #main.text.2, 55, 115, 180, 25
button     #main.butt.1,  "Reset",   [Reset], UL,  60, 160,  60, 25
button     #main.butt.2,  "Compute", [Compute], UL, 172, 160,  60, 25

open "Filtered Numeric Input" for window_nf as #main
#main "trapclose [Quit]"

#main.text.1, "?-?1,2##-#,$$$-$,$34???5-6??7$(8)9.5#0"

#main.text.1 "!contents? amt$"                      ' An example, just to get started
amt = NumberOnly(amt$)                              ' Make the conversion
#main.text.2, trim$(using("############.##", amt))  ' Put the result in the lower textbox
WAIT

[Compute]
#main.text.1 "!contents? amt$"                      ' Get the user's input

   ' We must allow decimal points, but more than 1 will give us an incorrect return.
   ' So the first thing to do is count them, and stop here if there is more than 1.
   ' Use this for severe error-checking.
   ' ALSO NOTE:
   ' If you enter a minus sign anywhere other than the first character, it will be
   ' stripped and ignored.  For example, enter 12-34 will result in 1234.00.
   ' -12-34 will result in -1234.00.

t = 0
for i = 1 to len(amt$)
   t$ = mid$(amt$, i, 1) : if t$ = "." then t = t + 1
   if t > 1 then notice "Only 1 decimal point is allowed in the number! " : wait
next

amt = NumberOnly(amt$)                              ' Make the conversion
#main.text.2, trim$(using("############.##", amt))  ' Put the result in the lower textbox
WAIT

[Reset]                                             ' Blank both the textboxes
#main.text.1, ""
#main.text.2, ""
#main.text.1 "!setfocus"                            ' Put the cursor in the upper textbox
WAIT

[Quit]
close #main
END


FUNCTION NumberOnly(in$)                            ' Here is the meat of it!
[Start]
for i = 1 to len(in$)
   t$ = mid$(in$, i, 1)
   select case
               ' Do nothing if t$ is a numeral or a decimal point
       case asc(t$) = 46 OR (asc(t$) > 47) AND (asc(t$) < 58)
               ' A minus sign is ok, as long as it preceeds the numbers
       case asc(t$) = 45 AND i = 1
               ' Discard any other character
       case else
           in$ = left$(in$, i - 1) + right$(in$, len(in$) - i)
           goto [Start]
   end select
next
NumberOnly = val(in$)
END FUNCTION