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Integer division in programming languages
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isInt() JavaScript function
assert, isdigit, isnan, tostring, parseint, isint, integer, int
22nd of May 2006
Here's my take on a function that determines if a variable is an integer or not before or after it's been recast to an int. The functionality is very similar to Python's isdigit() function which works like this:
>>> assert "1".isdigit()
>>> assert not "1.0".isdigit()
>>> assert not "1.0".isdigit()
However, my Javascript function should return true when the input is an integer or a string of an integer. Here it goes:
function isInt(x) {
var y=parseInt(x);
if (isNaN(y)) return false;
return x==y && x.toString()==y.toString();
}
assert(isInt("1"));
assert(isInt(1));
assert(!isInt("1a"));
assert(!isInt("1.0"));
var y=parseInt(x);
if (isNaN(y)) return false;
return x==y && x.toString()==y.toString();
}
assert(isInt("1"));
assert(isInt(1));
assert(!isInt("1a"));
assert(!isInt("1.0"));
You can see it in action here. To be honest, I'm writing about this here just to not forget it the next time I need a similar function. Sorry to cause any interweb-noise.
Comment
Kal -
16th April 2007
[«« Reply to this]
Am I allowed to use this function as long as I give you credit for it in my source code?
Am I allowed to use this function as long as I give you credit for it in my source code?
Okonomiyaki3000 -
11th December 2007
[«« Reply to this]
how about this:
String.prototype.isInt = function()
{
var re = new RegExp("^[\d]+$");
return this.match(re);
}
how about this:
String.prototype.isInt = function()
{
var re = new RegExp("^[\d]+$");
return this.match(re);
}
Thanx good idea i think. But are you sure the second part of the condition is useful?
Not sure:p
The second part is necessary so that "1.0" yields a false.
Indeed. My mistake:s