How do you determine if a value is an Integer?

wtf.php

 <?php

// Case 1 Produces:
// int_of_value: 0 is equal to value: dog
$value = 'dog';

$int_of_value = (int) $value;

if ($int_of_value == $value) {
    echo 'int_of_value: ' . $int_of_value . ' is equal to value: ' . $value;
} else {
    echo 'int_of_value: ' . $int_of_value . ' is NOT equal to value: ' . $value;
}

// Case 2 Produces:
// int_of_value: 0 is NOT equal to value: dog
$value = 'dog';

$int_of_value = (int) $value;

if ($int_of_value === $value) {
    echo 'int_of_value: ' . $int_of_value . ' is equal to value: ' . $value;
} else {
    echo 'int_of_value: ' . $int_of_value . ' is NOT equal to value: ' . $value;
}

// Case 3 Produces:
// int_of_value: 0 is NOT equal to value: dog
$value = '0';

$int_of_value = (int) $value;

if ($int_of_value === $value) {
    echo 'int_of_value: ' . $int_of_value . ' is equal to value: ' . $value;
} else {
    echo 'int_of_value: ' . $int_of_value . ' is NOT equal to value: ' . $value;
}

// Case 4 Produces:
// int_of_value: 0 is equal to value: 0
$value = 0;

$int_of_value = (int) $value;

if ($int_of_value === $value) {
    echo 'int_of_value: ' . $int_of_value . ' is equal to value: ' . $value;
} else {
    echo 'int_of_value: ' . $int_of_value . ' is NOT equal to value: ' . $value;
}

// Case 5 Produces:
// no
$value = '0';

if (is_integer($value)) {
    echo 'no';
} else {
    echo 'yes';
}

// Case 6 Produces:
// yes
$value = 0;

if (is_integer($value)) {
    echo 'no';
} else {
    echo 'yes';
}

for additional confusion you could also try ctype_digit http://php.net/manual/en/function.ctype-digit.php :)

What's wrong with if ((is_int($value)) || ctype_digit($value)) { ... }

Hi Amy. :)

How about :

        if ( filter_var ( $value , FILTER_VALIDATE_INT )){

            echo 'Bark like a dog';

        }

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What not to do

Many people will be tempted to use one or more of the following when faced with validating integers:

Cast the input to INT
Use ctype_digit()
Use is_numeric() 

These are all the wrong ways to approach this problem.

So, how do I fix it?

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^ info from here -> http://wiki.hashphp.org/Validation