[RESOLVED] a==0 ?

[dr_freak]

Hello,everyone.🙂

I am writing a code for validating whether the user has input a valid mobile phone number.It goes like this:

$num='a61752424';
for($i=0;$i<strlen($num);$i++)
{
	$match=false;
	$str=substr($num,$i,1);
	for($a=0;$a<=9;$a++)
	{
		if($str==$a)
		{
			$match=true;
		}
	}
	if(!$match)
		break;
}
if(!$match)
	echo "Input invalid.";
else
	echo "Input valid.";	

However,what surprise me is that,it turned out to be input valid!Why does the string a equal to 0?I don't know at all.

Please give me some clue on that.😉

[bpat1434]

If you're just checking for numbers, just use a simple regex:

if(preg_match('/[^0-9]+/', $string)) {
    // validation failed
} else {
    // Valid (well, it's all digits anyway
}

[Horizon88]

You could just use a regular expression instead.

$pattern = '/\d\d\d[-| ]\d\d\d[-| ]\d\d\d\d/';
if (!preg_match($pattern, $_POST['phone_number'])) {
   echo 'Please input a valid phone number.';
}

That regex oughta match a ten digit phone number formatted either with spaces or dashes. 405 554 3005, or 402-694-1000, for example, are both valid.

Edit: gah! always beating me, they are!

[Horizon88]

bpat1434 wrote:

If you're just checking for numbers, just use a simple regex:

if(preg_match('/[^0-9]+/', $string)) {
    // validation failed
} else {
    // Valid (well, it's all digits anyway
}

If all you're going to check is whether or not it's all numbers, why not just use is_numeric()?

if (!is_numeric($string)) {
   // invalid
}
// valid

[laserlight]

If all you're going to check is whether or not it's all numbers, why not just use is_numeric()?

Because is_numeric() allows for strings like '12.34' and '1e2'.

That said, regex is indeed not necessary is this special case since [man]ctype_digit/man does the job. On the other hand, things like a '+NN' country code prefix and such could mean that the mobile phone number format is actually more complicated and thus regex should be used.

[dr_freak]

laserlight,thanks for your help.🙂

P.S. Like what you've said,is_numeric is not suitable for checking digits.ctype_digit() is enough for me I think.😃 Horizon88,thanks for your help too,I appreciate it.

[laserlight]

You're welcome 🙂
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