Teach Yourself PHP in 10 Minutes [Electronic resources] نسخه متنی

Numeric Data Types

You have already seen that PHP assigns a data type to each value and that the numeric data types are integer and double, for whole numbers.

To check whether a value is either of these types, you use the is_float and is_int functions. Likewise, to check for either numeric data type in one operation, you can use is_numeric.

The following example contains a condition that checks whether the value of $number is an integer:

$number = "28";
if (is_int($number)) {
echo "$number is an integer";
}
else {
echo "$number is not an integer";
}

Because the actual declaration of that variable assigns a string valuealbeit one that contains a numberthe condition fails.

Although $number in the previous example is a string, PHP is flexible enough to allow this value to be used in numeric operations. The following example shows that a string value that contains a number can be incremented and that the resulting value is an integer:

$number = "6";
$number++;
echo "$number has type " . gettype($number);

Understanding NULLs

The value NULL is a data type all to itselfa value that actually has no value. It has no numeric value, but comparing to an integer value zero evaluates to true:

$number = 0;
$empty=NULL;
if ($number == $empty) {
echo "The values are the same";
}

Type Comparisons If you want to check that both the values and data types are the same in a condition, you use the triple equals comparison operator (===).