CODEWITHSUNDEEP
php
1199871
1199871

Reputation: 13

Php validate with preg_match

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';  
    }

Upvotes: 0

Views: 397

Answers (3)

user557846
user557846

Reputation: 

   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

Upvotes: 0

Vyktor
Vyktor

Reputation: 20997

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!');
}

Upvotes: 0

Petah
Petah

Reputation: 46050

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

Upvotes: 1

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