prevent to input string or integer value

Question

This is the PHP code and I want to check if an invalid value is present:

$response = $_POST['response'];
$visibility = $_POST['visibility'];


if($response == NULL || $visibility == NULL ){
    printf("Invalid input: %s\n", mysqli_connect_error());
    echo "<br/><a href='myevents.php'>Back to previous page</a>";
    exit();
}

$response and $visibility should be the integer value so If people put the string value I want to go to the if($response == NULL || $visibility == NULL ) statement. How to write the statement $response == ???

Linga · Accepted Answer · 2013-12-05 05:23:20Z

1

Using is_numeric will provide the desired result. is_numeric finds whether the given variable is numeric

if (!is_numeric($response) || is_numeric($visibility))
 echo "Invalid input";

Some people suggest is_int(). Don’t use is_int(). Use is_numeric() instead.

Copy the following chunk of code into a php file and run it. You’ll be surprised at the outcome:

$t = "12345";
if( is_int($t ) ) {
    echo $t . " is an int!";
} else {
    echo $t . " is not an int!";
}

The problem is that is_int() thinks a string of numbers is a string, not an integer.

The key difference between the two is the one checks the type of variable, is_int(), and the other checks the value of the variable, is_numeric().

edited Dec 5, 2013 at 5:23

answered Dec 5, 2013 at 5:11

Linga

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2 Comments

Lee Over a year ago

How is there some function for string value?

Linga Over a year ago

@Lee what do you want exactly

Krish R · Accepted Answer · 2013-12-05 05:19:20Z

Can you try using is_nan() function,

if(is_nan($response) || is_nan($visibility)){
    printf("Invalid input: %s\n", mysqli_connect_error());
    echo "<br/><a href='myevents.php'>Back to previous page</a>";
    exit();
}

var_dump(NAN == NAN); // boolean true
var_dump(NAN === NAN); // boolean true
var_dump(is_nan(NAN)); // boolean true

var_dump(NAN == 12); // boolean true
var_dump(NAN === 12); // boolean false
var_dump(is_nan(12)); // boolean false

var_dump(NAN == 12.4); // boolean true
var_dump(NAN === 12.4); // boolean true
var_dump(is_nan(12.4)); // boolean false

var_dump(NAN == NULL); // boolean true
var_dump(NAN === NULL); // boolean false
var_dump(is_nan(NULL)); // boolean false

var_dump(NAN == 'K<WNPO'); // boolean true
var_dump(NAN === 'K<WNPO'); // boolean false
var_dump(is_nan('K<WNPO')); // null and throws a warning "Warning: is_nan() expects parameter 1 to be double, string given in NANTest.php on line 13"

Ref: http://www.php.net/manual/en/function.is-nan.php

Syed Osama · Accepted Answer · 2013-12-05 05:25:18Z

0

try is_numeric or is_int

Follow these links:

http://php.net/is_int

http://www.php.net/is_numeric

answered Dec 5, 2013 at 5:25

Syed Osama

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1 Comment

Linga Over a year ago

Nope. is_int() finds whether the type of the given variable is integer. To test if a variable is a number or a numeric string (such as form input, which is always a string), you must use is_numeric().

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