Php validate with preg_match

Question

I try to validate fields. Three fields that may only contain numbers. The fields have the variable names $num1, $num2, $num3. I have put them in an array and then I run preg_match but it does not work. How should I do?

$valnum = array (‘$num1’, ‘$num2’, ‘$num3’);
    if (preg_match('/[0-9]/', $valnum)){
echo $mycost;
}
    else {
echo 'You can only enter numbers';  
    }

[0-9] will only match a single digit. Also, preg_match takes a string as its second parameter, not an array. — Etienne de Martel
– Etienne de Martel, Commented Feb 15, 2012 at 21:59
@EtiennedeMartel Actually [0-9] will match any string with a number in it. — Petah
– Petah, Commented Feb 15, 2012 at 22:00
Are you using a word processing tool such as MS word to write your code? You have typographical quotes in your code which will not work. You should really consider using a text editor such as Notepad++ or GVim! — ThiefMaster
– ThiefMaster, Commented Feb 16, 2012 at 1:10

Petah · Accepted Answer · 2012-02-15 22:03:28Z

1

Consider using filter_var as it is desgined for this type of validation:

$array = array(1, 2, 'a', 'b');
var_dump(filter_var_array($array, FILTER_VALIDATE_INT));

Output:

array
  0 => int 1
  1 => int 2
  2 => boolean false
  3 => boolean false

http://php.net/manual/en/function.filter-var-array.php

answered Feb 15, 2012 at 22:03

Petah

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3 Comments

user557846 Over a year ago

"numbers" may not = integers.

1199871 Over a year ago

I use is_numeric () now but I'll try this solution too when I get time. Thank you.

Petah Over a year ago

@Dagon php.net/manual/en/filter.constants.php will show you available filter types. Number being one of them.

score 0 · Accepted Answer · 2012-02-16 01:05:59Z

0

   is_numeric()

would be a better approach

//worked up example:

<?php
$num1 = '1';
$num2 = '11';
$num3 = '11.11';

$mycost = '$99.99';

$valnum = array($num1,$num2,$num3);
$check = '';
foreach($valnum as $element){
    if(!is_numeric($element)){
        $check = 'bad';
        break;
    }
}

if($check=='bad'){
    echo 'You can only enter numbers';
}else{
    echo $mycost;
}

?>

returns 99.99

edited Feb 16, 2012 at 1:05

answered Feb 15, 2012 at 22:02

user557846

9 Comments

1199871 Over a year ago

$valnum = array (‘$num1’, ‘$num2’, ‘$num3’); foreach ($valnum as $element) { if (is_numeric($element)) { echo $mycost; } else { echo 'You can only enter numbers'; } }

1199871 Over a year ago

I get the error message "You can only enter numbers" when I enter something in the fields, even numbers.

user557846 Over a year ago

I don't see how, sure they are all numbers? see worked up version above

1199871 Over a year ago

Sorry, I wrote $valnum = array('$num1','$num2','$num3'); but It works fine when I write $valnum = array($num1,$num2,$num3);

1199871 Over a year ago

I just wonder, shouldn't It work with'' around my variables in the array as well?

|

Vyktor · Accepted Answer · 2012-02-15 22:22:25Z

If you demand checking numeric input by preg_match() you should:

at first add ^ (start of string) and $ (end of string) meta characters to your regexp
add handling for floats
consider removing spaces from string (user may decide to input 1 800 instead of 1800)
use \d - escape sequence for decimal numbers group

So final regexp would look like: ~^\d+([.,]\d+)?$~.

You should rather use is_numeric() but according to manual it accepts "science format":

Finds whether the given variable is numeric. Numeric strings consist of optional sign, any number of digits, optional decimal part and optional exponential part. Thus +0123.45e6 is a valid numeric value. Hexadecimal notation (0xFF) is allowed too but only without sign, decimal and exponential part.

Which I personally avoid, this function just allows to input too much and you have to worry about transformation to valid form.

There'are two nice functions intval() and floatval() with just a little example:

$numbers = array( '1.8', '3', 'hello');

foreach( $numbers as $i){
    var_dump( $i);
    var_dump( intval( $i));
    var_dump( floatval( $i));
    echo "\n";
}

And output:

string(3) "1.8"
int(1)
float(1.8)

string(1) "3"
int(3)
float(3)

string(5) "hello"
int(0)
float(0)

Which allows you to do this:

php > $str = "3.8";
php > $i = intval( $str);
php > var_dump( $i == $str);
bool(false)
php > $str = "3";
php > $i = intval( $str);
php > var_dump( $i == $str);
bool(true)

You also can use filter_var(), but those functions just doesn't work for me and I'd build function like this:

function get_integer( $input){
    if( $input === null){
         return null;
    }

    if( $input === ''){
         return null;
    }

    $i = intval( $input);
    if( $i != $input){
         return null;
    }

    return $i;
}

$myCol = get_integer( $_POST['foo']);
if( $myCol === null){
    die( 'You naughty boy!');
}

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