CODEWITHSUNDEEP
php
Mark Estrada
Mark Estrada

Reputation: 9191

Validating a floating value in PHP

I started learning PHP to do some pet project, and I am trying to get this around my head on how to validate a valid float or double in PHP

Supposed I have this code in HTML that ask for interest rate

<input type="text" name="interest" size="5" >

In My PHP code, I wanted to validate if this is a valid interest rate:

<?php       
    $interest = $_POST['interest']
    //isset - empty test (not- shown)
    if(!is_numeric($interest) && is_float($interest)){
        print "<p><span class='error'>Interest should be numeric</span></p>";
    }
?>

I have my is_numeric() test first then I coupled it with the is_float() test but when I enter "1." (note the "." after the number) it should catch this but apparently not. I am not sure why "1." is a valid floating variable in PHP.

Upvotes: 2

Views: 4542

Answers (5)

Nodo
Nodo

Reputation: 95

Use PHP built-in function

filter_var("your float", FILTER_VALIDATE_FLOAT)

Upvotes: 2

Amin.Qarabaqi
Amin.Qarabaqi

Reputation: 723

i know this is too late. but solution i implemented:

function isFloat($floatString)
{
   return (bool)preg_match('/(^\d+\.\d+$|^\d+$)/',$floatString);
}

Upvotes: 1

Xorifelse
Xorifelse

Reputation: 7911

I have had a question why PHP picks up the 1. as a float as well, check out this question for more information.

There might be 1 reason why the code is failing, and that is because a any data retrieved from the http header (post, get, cookie) is a string type.

is_float() checks the type, not the content of the variable where is_numeric() only checks the value. However, you can try to convert the value by doing the following:

$interest = $_POST['interest'];

if(isset($interest)){
  if(is_numeric($interest) && !is_float($interest + 0)){
    echo "$interest is a integer";
  } else {
    echo "$interest is not an integer";
  }
} else {
  echo 'Value not posted';
}

If the value of $interest is a float, it stays a float. If it is a string that cannot be parsed as a float, it will convert it to 0, in which is_float() will return false because it is not a float. In short, now it will only except integer values.

You could also use the filter_var() method explained in deceze's post.

Upvotes: 1

Blinkydamo
Blinkydamo

Reputation: 1584

Another option

if( strpos( $interest, '.' ) )
{
    print "<p><span class='error'>Interest should be numeric</span></p>";
}

Upvotes: -1

deceze
deceze

Reputation: 522016

Since POST or GET data will always be a string, is_float will always be false. The easiest way to deal with that is to use methods specifically designed for it:

$interest = filter_input(INPUT_POST, 'interest', FILTER_VALIDATE_FLOAT);
if (!$interest) {  // take care here if you expect 0 to be valid
    print 'Nope';
}

See http://php.net/filter_input.

Upvotes: 3

Related Questions