prevent to input string or integer value - php

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 == ???

Answer 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().

Answer 2

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

Answer 3

try is_numeric or is_int
Follow these links:
http://php.net/is_int
http://www.php.net/is_numeric