问题
A select field on my HTML form may yield 1 to 5 (integers). Using is_int rejects it every time, because the $_POST['rating'] is viewed as a string.
After consulting the PHP Manual, it seems is_numeric() && !is_float() is the proper way to validate for an integer in this case.
But I want to be certain, so please confirm or fire away at my logic.
回答1:
I would use is_numeric(), because user input always comes in as a string (as far as I know).
Another way to guarantee something is an integer is to cast it...
$id = (int) $id;
回答2:
I would probably use something like this:
$value = filter_var(
$_POST['rating'],
FILTER_VALIDATE_INT,
array('options' => array('min_range' => 1, 'max_range' => 5)));
filter_var() will return either boolean false if the value is non-integer or out-of-range, or the valid value itself (as an integer.)
回答3:
You could use the following regular expression:
preg_match('/^[0-9]{1,}$/', $value);
I does validate digits with leading zeros though...
回答4:
is_int requires the input content is a integer.
is_numeric requires the input content is a integer or a string including just 0-9.
but I am wondering the result if I put a number that is bigger than PHP_INT_MAX as the parameter into the above 2 functions.
回答5:
You can always cast it as an int.
$rating = (int)$_POST['rating'];
This will remove the need to validate it (even though you should always validate form data).
It may reduce your steps is what I'm getting at.
回答6:
If you're testing for digits only (what an integer usually is ;)), I tend to use ctype_digit instead of is_int. That way, you won't lose data through casting, and you can just use a string:
$_POST['foo'] = '42';
echo ctype_digit( (string) $_POST['foo'] ) ? 'yep' : 'nope';
That'll output "yep".
回答7:
if you want to know if $_POST['rating'] is an int before you even try to cast do use is_numeric() && !is_float() as you have. This will tell you if the string is an int or not. If you just cast to an int and there is a non numeric all the numbers before the first letter in the string is turned into an int.
x = 457h
print (int)x
outputs 457
x = h56
print (int)x
outputs 0
来源：https://stackoverflow.com/questions/5486926/is-int-is-numeric-is-float-and-html-form-validation
