THE WORLD'S LARGEST WEB DEVELOPER SITE

PHP Tutorial

PHP HOME PHP Intro PHP Install PHP Syntax PHP Comments PHP Variables PHP Echo / Print PHP Data Types PHP Strings PHP Numbers PHP Constants PHP Operators PHP If...Else...Elseif PHP Switch PHP While Loops PHP For Loops PHP Functions PHP Arrays PHP Superglobals

PHP Forms

PHP Form Handling PHP Form Validation PHP Form Required PHP Form URL/E-mail PHP Form Complete

PHP Advanced

PHP Date and Time PHP Include PHP File Handling PHP File Open/Read PHP File Create/Write PHP File Upload PHP Cookies PHP Sessions PHP Filters PHP Filters Advanced PHP JSON

PHP OOP

PHP What is OOP PHP Classes/Objects PHP Constructor PHP Destructor PHP Access Modifiers PHP Inheritance PHP Constants PHP Abstract Classes PHP Traits PHP Static Methods PHP Static Properties

MySQL Database

MySQL Database MySQL Connect MySQL Create DB MySQL Create Table MySQL Insert Data MySQL Get Last ID MySQL Insert Multiple MySQL Prepared MySQL Select Data MySQL Delete Data MySQL Update Data MySQL Limit Data

PHP XML

PHP XML Parsers PHP SimpleXML Parser PHP SimpleXML - Get PHP XML Expat PHP XML DOM

PHP - AJAX

AJAX Intro AJAX PHP AJAX Database AJAX XML AJAX Live Search AJAX Poll

PHP Examples

PHP Examples PHP Quiz PHP Exercises PHP Certificate

PHP Reference

PHP Overview PHP Array PHP Calendar PHP Date PHP Directory PHP Error PHP Filesystem PHP Filter PHP FTP PHP JSON PHP Libxml PHP Mail PHP Math PHP Misc PHP MySQLi PHP Network PHP SimpleXML PHP Stream PHP String PHP XML Parser PHP Zip PHP Timezones

PHP Numbers


In this chapter we will look in depth into Integers, Floats, and Number Strings.


PHP Numbers

One thing to notice about PHP is that it provides automatic data type conversion.

So, if you assign an integer value to a variable, the type of that variable will automatically be an integer. Then, if you assign a string to the same variable, the type will change to a string.

This automatic conversion can sometimes break your code.


PHP Integers

An integer is a number without any decimal part.

2, 256, -256, 10358, -179567 are all integers. While 7.56, 10.0, 150.67 are floats.

So, an integer data type is a non-decimal number between -2147483648 and 2147483647. A value greater (or lower) than this, will be stored as float, because it exceeds the limit of an integer.

Another important thing to know is that even if 4 * 2.5 is 10, the result is stored as float, because one of the operands is a float (2.5).

Here are some rules for integers:

  • An integer must have at least one digit
  • An integer must not have a decimal point
  • An integer can be either positive or negative
  • Integers can be specified in three formats: decimal (10-based), hexadecimal (16-based - prefixed with 0x) or octal (8-based - prefixed with 0)

PHP has the following functions to check if the type of a variable is integer:

  • is_int()
  • is_integer() - alias of is_int()
  • is_long() - alias of is_int()

Example

Check if the type of a variable is integer:

<?php
$x = 5985;
var_dump(is_int($x));

$x = 59.85;
var_dump(is_int($x));
?>
Try it Yourself »


PHP Floats

A float is a number with a decimal point or a number in exponential form.

2.0, 256.4, 10.358, 7.64E+5, 5.56E-5 are all floats.

The float data type can commonly store a value up to 1.7976931348623E+308 (platform dependent), and have a maximum precision of 14 digits.

PHP has the following functions to check if the type of a variable is float:

  • is_float()
  • is_double() - alias of is_float()

Example

Check if the type of a variable is float:

<?php
$x = 10.365;
var_dump(is_float($x));
?>
Try it Yourself »

PHP Infinity

A numeric value that is larger than PHP_FLOAT_MAX is considered infinite.

PHP has the following functions to check if a numeric value is finite or infinite:

However, the PHP var_dump() function returns the data type and value:

Example

Check if a numeric value is finite or infinite:

<?php
$x = 1.9e411;
var_dump($x);
?>
Try it Yourself »

PHP NaN

NaN stands for Not a Number.

NaN is used for impossible mathematical operations.

PHP has the following functions to check if a value is not a number:

However, the PHP var_dump() function returns the data type and value:

Example

Invalid calculation will return a NaN value:

<?php
$x = acos(8);
var_dump($x);
?>
Try it Yourself »

PHP Numerical Strings

The PHP is_numeric() function can be used to find whether a variable is numeric. The function returns true if the variable is a number or a numeric string, false otherwise.

Example

Check if the variable is numeric:

<?php
$x = 5985;
var_dump(is_numeric($x));

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

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

$x = "Hello";
var_dump(is_numeric($x));
?>
Try it Yourself »

Note: From PHP 7.0: The is_numeric() function will return FALSE for numeric strings in hexadecimal form (e.g. 0xf4c3b00c), as they are no longer considered as numeric strings.


PHP Casting Strings and Floats to Integers

Sometimes you need to cast a numerical value into another data type.

The (int), (integer), or intval() function are often used to convert a value to an integer.

Example

Cast float and string to integer:

<?php
// Cast float to int
$x = 23465.768;
$int_cast = (int)$x;
echo $int_cast;

echo "<br>";

// Cast string to int
$x = "23465.768";
$int_cast = (int)$x;
echo $int_cast;
?>
Try it Yourself »