isInteger, isFloat functions?

[D. Alvarado]

Hello,
Does anyone have handy functions for testing whether a text field value is

a) a valid integer
b) a valid floating point number?

Thanks for any assistance, - Dave

[RobG]

Re: isInteger, isFloat functions?

D. Alvarado wrote:[color=blue]
> Hello,
> Does anyone have handy functions for testing whether a text field value is
>
> a) a valid integer
> b) a valid floating point number?[/color]

Try the FAQ:

http://www.jibbering.com/faq/#FAQ4_12

Follow the links for parseInt and parseFloat - choose your
- poison MS or Netscape. I think the Netscape reference is
better on this one. You may find isNaN useful too.

Cheers, Rob.

[Fox]

Re: isInteger, isFloat functions?



RobG wrote:[color=blue]
> D. Alvarado wrote:
>[color=green]
>> Hello,
>> Does anyone have handy functions for testing whether a text field
>> value is
>> a) a valid integer
>> b) a valid floating point number?[/color]
>
>
> Try the FAQ:
>
> http://www.jibbering.com/faq/#FAQ4_12
>
> Follow the links for parseInt and parseFloat - choose your
> - poison MS or Netscape. I think the Netscape reference is
> better on this one. You may find isNaN useful too.
>
> Cheers, Rob.[/color]

parseInt and parseFloat will both accept non-numeric characters in a string and
return the digits used up to the first non-digit character -- e.g.:

parseInt("123ab c") will return 123 [a "true"]
parseFloat("123 .2abc") will return 123.2 [also a "true"]

technically, you cannot pass either of these to an "isInteger" and "isFloat" and
receive a true -- they should both be false.

[Fox]

Re: isInteger, isFloat functions?



D. Alvarado wrote:[color=blue]
> Hello,
> Does anyone have handy functions for testing whether a text field value is
>
> a) a valid integer[/color]

function
isInteger(s)
{
var n = trim(s);
return n.length > 0 && !(/[^0-9]/).test(n);

}
[color=blue]
> b) a valid floating point number?[/color]

function
isFloat(s)
{
var n = trim(s);
return n.length>0 && !(/[^0-9.]/).test(n) && (/\.\d/).test(n);
}


isFloat "qualifies" and differentiates from an integer by testing for a decimal
point and at least one digit after it. Therefore, 123. will not qualify as a
floating point number [nor an integer in isInteger] -- it is an invalid input.
If you require a digit *before* the decimal point for a float, you'll have to
adjust the regex.

These routines merely test for *any* non-digit(/non-numeric) character
(therefore the 'g' selector in the regex is not required).
[note: empty strings will return a "false positive" - that's why testing for
string length]

To trim away any spaces before or after the string:

function
trim(s)
{
return s.replace(/^\s+|\s+$/g, "");
}


You can test for Integer OR Float with:

function
isNumber(s)
{
var n = trim(s);
return n.length>0 && +n == n;
}

or you can use !isNaN(numstr) on a non-empty string. [!isNaN("") returns true
and isNaN apparently trims strings of whitespace before testing]

[Evertjan.]

Re: isInteger, isFloat functions?

D. Alvarado wrote on 20 sep 2004 in comp.lang.javas cript:[color=blue]
> Does anyone have handy functions for testing whether a text field
> value is
>
> a) a valid integer[/color]

t = " -12.345"
alert(!/\./.test(t) && +t==t)
t = " -12345"
alert(!/\./.test(t) && +t==t)
[color=blue]
> b) a valid floating point number?[/color]

t = " -12.34.5"
alert(+t==t)
t = " -12.345"
alert(+t==t)

Shoot!


--
Evertjan.
The Netherlands.
(Please change the x'es to dots in my emailaddress,
but let us keep the discussions in the newsgroup)

[Philip Ronan]

Re: isInteger, isFloat functions?

On 20/9/04 10:54 am, Evertjan. wrote:
[color=blue]
> D. Alvarado wrote on 20 sep 2004 in comp.lang.javas cript:[color=green]
>> Does anyone have handy functions for testing whether a text field
>> value is
>>
>> a) a valid integer[/color]
>
> t = " -12.345"
> alert(!/\./.test(t) && +t==t)
> t = " -12345"
> alert(!/\./.test(t) && +t==t)
>[color=green]
>> b) a valid floating point number?[/color]
>
> t = " -12.34.5"
> alert(+t==t)
> t = " -12.345"
> alert(+t==t)
>
> Shoot!
>[/color]

<pedant>
what about t = "1.2e+03"?
</pedant>

--
Philip Ronan
phil.ronanzzz@v irgin.net
(Please remove the "z"s if replying by email)

[Evertjan.]

Re: isInteger, isFloat functions?

Philip Ronan wrote on 20 sep 2004 in comp.lang.javas cript:[color=blue]
> On 20/9/04 10:54 am, Evertjan. wrote:[color=green][color=darkred]
>>> a) a valid integer[/color]
>>
>> t = " -12.345"
>> alert(!/\./.test(t) && +t==t)
>> t = " -12345"
>> alert(!/\./.test(t) && +t==t)
>>[/color][/color]
[..][color=blue]
>
> <pedant>
> what about t = "1.2e+03"?
> </pedant>
>[/color]

t = "1.2e+03"
alert(!/\./.test(+t) && +t==t)
t = "5.0000"
alert(!/\./.test(+t) && +t==t)

will take care of those.

However, it will miserably fail here:

t = "1.2e+33"
alert(!/\./.test(+t) && +t==t)

Though technically incorrect [John?],
are such big/small numbers important to the OP ?


--
Evertjan.
The Netherlands.
(Please change the x'es to dots in my emailaddress,
but let us keep the discussions in the newsgroup)

[Philip Ronan]

Re: isInteger, isFloat functions?

On 20/9/04 11:15 am, Evertjan. wrote:
[color=blue]
> t = "1.2e+03"
> alert(!/\./.test(+t) && +t==t)
> t = "5.0000"
> alert(!/\./.test(+t) && +t==t)
>
> will take care of those.
>
> However, it will miserably fail here:
>
> t = "1.2e+33"
> alert(!/\./.test(+t) && +t==t)[/color]

It will also fail when t = infinity (e.g., "t=1/0")

How about:

alert(!/\./.test(+t) && +t==t && (t+1)!=t)

--
Philip Ronan
phil.ronanzzz@v irgin.net
(Please remove the "z"s if replying by email)

[Fred Oz]

Re: isInteger, isFloat functions?

Fox wrote:

[color=blue]
> technically, you cannot pass either of these to an "isInteger" and
> "isFloat" and receive a true -- they should both be false.
>
>[/color]

I think Rob is on the right track (but could have offered some
code...)

Testing strings using regular expressions to see if they have
decimal places (and how many), surplus characters, scientific
notation, etc. requires exhaustive testing... let JS do
the work.

How about:

var x = someValue;
if (x == parseInt(x) && x == parseFloat(x)) {
alert(x + ' is a int');
} else if (x == parseFloat(x)) {
alert(x + ' is a float');
} else {
alert(x + ' is not a number I like...');
}

You can even use scientific notation if you like, so 1.2e+03 is
recognised as a float quite happily without complex pattern
matching.

Cheers, Fred

[Evertjan.]

Re: isInteger, isFloat functions?

Philip Ronan wrote on 20 sep 2004 in comp.lang.javas cript:[color=blue]
> It will also fail when t = infinity (e.g., "t=1/0")
>
> How about:
>
> alert(!/\./.test(+t) && +t==t && (t+1)!=t)[/color]

I don't think infinity is an integer but I wouldn't mind if it is.

(+t+1)!=+t ?

--
Evertjan.
The Netherlands.
(Please change the x'es to dots in my emailaddress,
but let us keep the discussions in the newsgroup)

[Fred Oz]

Re: isInteger, isFloat functions?

Philip Ronan wrote:

[color=blue]
> It will also fail when t = infinity (e.g., "t=1/0")
>[/color]

1/0 is not infinity, is it "undefined"- as is the result
of any division by zero.

Cheers, Fred.

[Philip Ronan]

Re: isInteger, isFloat functions?

On 20/9/04 12:44 pm, Fred Oz wrote:
[color=blue]
> Philip Ronan wrote:
>
>[color=green]
>> It will also fail when t = infinity (e.g., "t=1/0")
>>[/color]
>
> 1/0 is not infinity, is it "undefined"- as is the result
> of any division by zero.
>
> Cheers, Fred.[/color]

Really?
javascript:aler t(1/0) returns "Inf" in IE.

--
Philip Ronan
phil.ronanzzz@v irgin.net
(Please remove the "z"s if replying by email)

[Fred Oz]

Re: isInteger, isFloat functions?

Philip Ronan wrote:

[color=blue]
> Really?
> javascript:aler t(1/0) returns "Inf" in IE.
>[/color]

And now IE is an authority on mathematics? Heaven forbid!

Please read here:

http://home.ubalt.edu/ntsbarsh/zero/ZERO.HTM#rsimpalgcom

Have a good one, Fred.

[Andrew Thompson]

Re: isInteger, isFloat functions?

On Mon, 20 Sep 2004 13:12:39 +0100, Philip Ronan wrote:[color=blue]
> On 20/9/04 12:44 pm, Fred Oz wrote:[color=green]
>> Philip Ronan wrote:
>>[color=darkred]
>>> It will also fail when t = infinity (e.g., "t=1/0")[/color][/color][/color]
...[color=blue][color=green]
>> 1/0 is not infinity, is it "undefined"- as is the result
>> of any division by zero.[/color][/color]
...[color=blue]
> javascript:aler t(1/0) returns "Inf" in IE.[/color]

All three of IE 6.0026, Moz. 1.7 and Opera 6.54
give consistent results for me..

javascript:aler t(1/0) -> 'Infinity'
javascript:aler t(0/0) -> 'NaN'
javascript:aler t(-1/0) -> '-Infinity'

Makes perfect sense to me.

--
Andrew Thompson
http://www.PhySci.org/codes/ Web & IT Help
http://www.PhySci.org/ Open-source software suite
http://www.1point1C.org/ Science & Technology
http://www.lensescapes.com/ Images that escape the mundane

[Evertjan.]

Re: isInteger, isFloat functions?

Andrew Thompson wrote on 20 sep 2004 in comp.lang.javas cript:
[color=blue]
> All three of IE 6.0026, Moz. 1.7 and Opera 6.54
> give consistent results for me..
>
> javascript:aler t(1/0) -> 'Infinity'
> javascript:aler t(0/0) -> 'NaN'
> javascript:aler t(-1/0) -> '-Infinity'
>
> Makes perfect sense to me.
>[/color]

And which of them are integers ?
;-}

--
Evertjan.
The Netherlands.
(Please change the x'es to dots in my emailaddress,
but let us keep the discussions in the newsgroup)