문자열이 현재 정수인지 여부를 판별 할 수 없습니다.

Question

다음 funciton은 나를 끌어 냈습니다.지구 100 배가 100과 같을 수있는 방법은 100 배가 정수로보고됩니까? 나의 삶을 위해, 나는 그것을 알아낼 수 없다. 당신은 모든 것을 복사하여 붙여 넣고 자신을 위해 그것을 볼 수 있습니다.
어딘가에있는 간단한 지점을 놓치고, 나를 도와주세요.

function blp_int($val) {
    $orgval = $val;
    $num = (int)$val;    
    echo "<li><font color=red>val: ". $val . " is being checked to see if it's an integer or not";
    echo "<li><font color=red>orgval: ". $orgval ;
    echo "<li><font color=red>num: ". $num ;
    if ($orgval==$num) {
        echo "<li><font color=red><b>YES IT IS! the [{$orgval}] is equal to [{$num}]</b>";
        return true;
    }
    return false;
}

if (blp_int("100"))
{
    echo "<h1>100 is an integer!</h1>";
}
else
{
    echo "<h1>100 is NOT an integer!</h1>";
}

if (blp_int("100x"))
{
    echo "<h1>100x is an integer!</h1>";
}
else
{
    echo "<h1>100x is NOT an integer!</h1>";
}

.

위의 코드는 다음을 반환합니다.

val: 100 is being checked to see if it's an integer or not
orgval: 100
num: 100
YES IT IS. the [100] is equal to [100]
100 is an integer!

val: 100x is being checked to see if it's an integer or not
orgval: 100x
num: 100
YES IT IS. the [100x] is equal to [100]
100x is an integer!

.

다음 비트를 추가하여 상황을 해결할 수 있습니다

    if (!is_numeric($val))
    {
        return false;
    }

.

BLP_INT 기능의 맨 위로 바로 박쥐가 바로 떨어져 있지만, 지구의 PHP가 100 배= 100이 같다고 생각하는 이유를 알아내는 것은 아직도 호기심입니다.

Answer 1

As you can see in this example, casting 100x as an integer converts it to 100. Since you are not using strict comparison, '100x' == 100 is true. PHP removes the x from it to make just 100.

You could use strict comparison (which also compares the types), such that '100x' === 100 would return false. Using it, any time a string was compared to an integer, it would return false.

---

As per your edit: is_numeric may not be the most reliable, as it will return true for numbers formatted as a string, such as '100'. If you want the number to be an integer (and never a string), you could use is_integer instead. I'm not quite sure what exactly you're doing, but i thought I'd add this note.

Answer 2

I think you should use three equal signs in your IF:

if ($orgval===$num) {

Otherwise PHP casts the value 100x to 100 and 100=100.

Documentation: Comparison Operators

Answer 3

What kind of check do you want to do? There are a few ways you could go about it:

if (preg_match('!^[0-9]+$!', $input))

if (intval($input) == $input)

if (intval($input) === $input)

if ('x'.intval($input) === 'x'.$input)

It depends on how closely you want to check if it's an integer. Does it matter if you need to trim() it first?

Answer 4

Either cast it to an int or try http://php.net/manual/en/function.ctype-digit.php. You also need === in your if.