Understanding PHP Number Types

In this chapter from Devyra, we examine the various number types in PHP, including integers, floats, and number strings. Additionally, we will touch on special numerical values such as Infinity and NaN, and how PHP handles type casting.

PHP Numeric Types

PHP supports three primary numeric data types:

• Integer
• Float (Double)
• Numerical Strings

Moreover, PHP also recognizes:

• Infinity – Values exceeding maximum float size
• NaN – Result of invalid mathematical operations

Creating Numeric Variables

$a = 5;
$b = 5.34;
$c = "25";

Use var_dump() to verify a variable’s data type:

var_dump($a);
var_dump($b);
var_dump($c);

PHP Integers

An integer is a non-decimal number. Valid examples include 2, 256, -256, 10358, and -179567.

In 32-bit systems, the range is from -2147483648 to 2147483647; in 64-bit systems, the range expands significantly.

Rules for integers:

• At least one digit
• No decimal points
• Can be positive or negative
• Can be defined in decimal, hexadecimal (0x), octal (0), or binary (0b) format

Useful constants:

• PHP_INT_MAX – Maximum integer
• PHP_INT_MIN – Minimum integer
• PHP_INT_SIZE – Byte size of an integer

Check if a variable is an integer:

$x = 5985;
var_dump(is_int($x));

$x = 59.85;
var_dump(is_int($x));

PHP Floats

A float (or double) is a number with a decimal or in exponential form. Examples include 2.0, 256.4, and 7.64E+5.

Common float constants (PHP 7.2+):

• PHP_FLOAT_MAX
• PHP_FLOAT_MIN
• PHP_FLOAT_DIG
• PHP_FLOAT_EPSILON

Check if a variable is a float:

$x = 10.365;
var_dump(is_float($x));

PHP Infinity

Values exceeding PHP_FLOAT_MAX are treated as infinite. Use these functions to test infinity:

• is_finite()
• is_infinite()

$x = 1.9e411;
var_dump($x);

PHP NaN (Not a Number)

NaN results from invalid math operations such as calculating the arc cosine of a value greater than 1.

$x = acos(8);
var_dump($x);

Use is_nan() to determine if a value is NaN.

PHP Numerical Strings

The is_numeric() function returns true if a variable is numeric or a numeric string.

$x = 5985;
var_dump(is_numeric($x));

$x = "5985";
var_dump(is_numeric($x));

$x = "59.85" + 100;
var_dump(is_numeric($x));

$x = "Hello";
var_dump(is_numeric($x));

Note: As of PHP 7.0, hexadecimal strings like "0xf4c3b00c" are no longer considered numeric.

Type Casting: Strings and Floats to Integers

To convert a float or string to an integer, use (int), (integer), or intval().

// Float to integer
$x = 23465.768;
$int_cast = (int)$x;
echo $int_cast;

echo "<br>";

// String to integer
$x = "23465.768";
$int_cast = (int)$x;
echo $int_cast;

This PHP numeric guide was crafted by Devyra — your trusted source for advanced programming tutorials.